What's the difference between native, drought tolerant, and desert adapted plants?

Maybe you have heard these terms in relation to plants grown in the Tucson area and thought they were interchangeable. Or maybe at least you knew what one or two meant. Actually, the meanings are not necessarily interchangeable, and in some cases they mean completely different things.

By far the best plant choices, if you are looking for a low water and maintenance landscape, are those considered native to the area. Just keep in mind that not all Arizona native plants will survive in all parts of Arizona. For example, the Fremont cottonwood is native to riparian areas, but it is not a good choice as the water requirements are over 250 gallons per day for a mature tree. That’s not smart water use. Ponderosa Pines are right at home in Northern Arizona and in the mountains of Southern Arizona, but that doesn’t mean they will grow in Tucson.

Drought tolerant plants are those species that thrive on minimal irrigation. This does include native desert species, but not exclusively. For example, the Texas Ranger, even though not native to Arizona, is quite drought tolerant and happy in high heat and cold temperatures.

Desert adapted plants are those adapted to some desert conditions; but the caveat is not necessarily our desert. There are many deserts in the world, all of which contribute species to our list of choices, but many can’t take our freezing temperatures, blazing summer sun, or alkaline soils.

The best way to assure you are selecting plants that will not require excessive amounts of water or protection from frosts is to research what is hardy before buying. The Sunset Western Garden Book is worth purchasing, even if a used book, as it contains thousands of plants with detailed descriptions of the plant, where it is from, and where it will grow. In addition, unlike the USDA Hardiness Zone Map, which treats the United States not only as though it is flat, but ignores latitude, Sunset’s Climate Zone Maps are more realistic. Sunset’s Climate Zones take into account latitude, microclimates, valleys and mountains, which makes sense when you consider that the USDA lumps Tucson and Seattle into the same zone. Go figure.

Cactus choices for flowers

Argentine Hedgehog

It is easy to forget how dramatic our desert cactus are. For most of the year, they just kind of sit there and blend in with the desert. Cactus make great additions to desert landscaping even when they are not blooming, but if flowers are what you are after, here are some stunning choices.

Engelmann's Prickly Pear

The Engelmann’s Prickly Pear is one of our most common cactus species. The bright yellow flowers are following by red fruits relished by birds.

Santa Rita Prickly Pear

The Santa Rita Prickly Pear is named after the Santa Rita Mountains in Southern Arizona. The purple pads add color even when the plant is not sporting yellow flowers. It’s interesting to note that botanists don’t really know exactly why the pads are purple. Some think it’s tied to cold weather, some to drought stress, others to genetics. Whatever the reason, if pays to buy a very purple one to begin with.

Engelmann’s Hedgehog is a notable native, with stunning magenta flowers on a small, compact plant.

Look to the pincushion species for flower shows to rival all others. Hot pink flowers are easy to spot from long distances, even though the plant is under 6 inches tall.

Arizona Fishhook

The stately sahuaro is a summer bloomer, with white flowers appearing on the top, sides and arms. Pollinated by bats, these flowers produce delicious fruits still harvested the traditional way by Native Americans.

Although not a native, the Argentine Giant handles heat and cold, but it does prefer part shade in the hot desert. The flowers are white, and up to six inches across. The Argentine Hedgehog is another hardy cactus from the same region. Taller than other hedgehog species, the stems reach up to two feet tall. The flowers are an amazing red-orange, and also up to six inches across.

Cactus need little care, and will suffer if you give them too much care. Avoid watering cactus in the ground unless they are drought stressed. Container cactus, however do need water—weekly in the summer if they are in full sun.

Creating a desert butterfly garden

Lantana

Backyard bird watching is a favorite activity of desert dwellers, since so many species visit warm climates during the winter. Many landscape plants are selected because they attract birds. Another way to bring colorful, living visitors to your home is planting a butterfly garden. The best part is, you can bring some of the 250 southwest butterfly species to your yard by using desert natives and desert adapted plants.

What do Butterflies like?

Butterflies like plants with colorful flowers. White flowers do not seem to interest them. In general, they need flowers that are easy to sit on, so they don’t pick tubular flowers like hummingbirds. Butterflies like their flowers flat. But like hummingbirds, they do feed on nectar. To attract and keep butterflies, you need not only flowers, but plants for caterpillar food. This way you are attracting them for their whole life cycle. The more variety you have, the more different kinds of butterflies you will see. Some butterflies are very fussy and pick only certain kinds of plants, while others don’t care much. For the widest variety of visitors, plant a wide variety of plants.

Plants to Attract Caterpillars

Plants to include in your butterfly garden include the following:

• Pine-leaf milkweed (Asclepias linaria)
• Narrowleaf milkweed (Asclepias subulata)
• Butterflyweed (Asclepias tuberose
• Fern acacia (Acacia angustissima)
• Globemallow (Sphaeralcea ambigua)
• Sideoats grama (Bouteloua curtipendula)
• Bamboo muhly (Muhlenbergia dumosa)
• Green spangletop (Leptochloa dubia)
• Goosefoot (Chenopodia fremontii)
• Saltbush (Atriplex elegans)

Flowering Plants to Attract Butterflies

Your butterfly garden can have just flowering butterfly attracting plants, or a combination of both caterpillar food plants and plants with flowers. Butterfly magnet plants include:

·        Kidneywood (Eysenhardtia orthocarpa)

·        Bee bush (Aloysia gratissima)

·        Lantana species (Lantana camara, Lantana montevidensis)

·        Red bird of paradise (Caesalpinia pulcherrima)

·        Butterfly mist (Ageratum corymbosum)

·        Black dalea (Dalea pulchra)

Planting your Butterfly Garden

Fall is the best time to plant desert native plants or seeds. The November rains, cooler days and nights trigger germination of seeds, and while the air may be cooler the soil is still warm, encouraging root establishment. This is important for plants to make it through the first summer.

Finding Seed Sources

Many of the plants mentioned above are desert natives, and may be hard to find. Do not harvest seeds or plants from the desert; check online for sources, or find a local nursery specializing in native desert plants.

Creating a desert butterfly garden

Lantana

Backyard bird watching is a favorite activity of desert dwellers, since so many species visit warm climates during the winter. Many landscape plants are selected because they attract birds. Another way to bring colorful, living visitors to your home is planting a butterfly garden. The best part is, you can bring some of the 250 southwest butterfly species to your yard by using desert natives and desert adapted plants.

What do Butterflies like?

Butterflies like plants with colorful flowers. White flowers do not seem to interest them. In general, they need flowers that are easy to sit on, so they don’t pick tubular flowers like hummingbirds. Butterflies like their flowers flat. But like hummingbirds, they do feed on nectar. To attract and keep butterflies, you need not only flowers, but plants for caterpillar food. This way you are attracting them for their whole life cycle. The more variety you have, the more different kinds of butterflies you will see. Some butterflies are very fussy and pick only certain kinds of plants, while others don’t care much. For the widest variety of visitors, plant a wide variety of plants.

Plants to Attract Caterpillars

Plants to include in your butterfly garden include the following:

• Pine-leaf milkweed (Asclepias linaria)
• Narrowleaf milkweed (Asclepias subulata)
• Butterflyweed (Asclepias tuberose
• Fern acacia (Acacia angustissima)
• Globemallow (Sphaeralcea ambigua)
• Sideoats grama (Bouteloua curtipendula)
• Bamboo muhly (Muhlenbergia dumosa)
• Green spangletop (Leptochloa dubia)
• Goosefoot (Chenopodia fremontii)
• Saltbush (Atriplex elegans)

Flowering Plants to Attract Butterflies

Your butterfly garden can have just flowering butterfly attracting plants, or a combination of both caterpillar food plants and plants with flowers. Butterfly magnet plants include:

·        Kidneywood (Eysenhardtia orthocarpa)

·        Bee bush (Aloysia gratissima)

·        Lantana species (Lantana camara, Lantana montevidensis)

·        Red bird of paradise (Caesalpinia pulcherrima)

·        Butterfly mist (Ageratum corymbosum)

·        Black dalea (Dalea pulchra)

Planting your Butterfly Garden

Fall is the best time to plant desert native plants or seeds. The November rains, cooler days and nights trigger germination of seeds, and while the air may be cooler the soil is still warm, encouraging root establishment. This is important for plants to make it through the first summer.

Finding Seed Sources

Many of the plants mentioned above are desert natives, and may be hard to find. Do not harvest seeds or plants from the desert; check online for sources, or find a local nursery specializing in native desert plants.

Creating a desert butterfly garden

Backyard bird watching is a favorite activity of desert dwellers, since so many species visit warm climates during the winter. Many landscape plants are selected because they attract birds. Another way to bring colorful, living visitors to your home is planting a butterfly garden. The best part is, you can bring some of the 250 southwest butterfly species to your yard by using desert natives and desert adapted plants.

What do Butterflies like?

Butterflies like plants with colorful flowers. White flowers do not seem to interest them. In general, they need flowers that are easy to sit on, so they don’t pick tubular flowers like hummingbirds. Butterflies like their flowers flat. But like hummingbirds, they do feed on nectar. To attract and keep butterflies, you need not only flowers, but plants for caterpillar food. This way you are attracting them for their whole life cycle. The more variety you have, the more different kinds of butterflies you will see. Some butterflies are very fussy and pick only certain kinds of plants, while others don’t care much. For the widest variety of visitors, plant a wide variety of plants.

Plants to Attract Caterpillars

Plants to include in your butterfly garden include the following:

• Pine-leaf milkweed (Asclepias linaria)
• Narrowleaf milkweed (Asclepias subulata)
• Butterflyweed (Asclepias tuberose
• Fern acacia (Acacia angustissima)
• Globemallow (Sphaeralcea ambigua)
• Sideoats grama (Bouteloua curtipendula)
• Bamboo muhly (Muhlenbergia dumosa)
• Green spangletop (Leptochloa dubia)
• Goosefoot (Chenopodia fremontii)
• Saltbush (Atriplex elegans)

Flowering Plants to Attract Butterflies

Your butterfly garden can have just flowering butterfly attracting plants, or a combination of both caterpillar food plants and plants with flowers. Butterfly magnet plants include:

·        Kidneywood (Eysenhardtia orthocarpa)

·        Bee bush (Aloysia gratissima)

·        Lantana species (Lantana camara, Lantana montevidensis)

·        Red bird of paradise (Caesalpinia pulcherrima)

·        Butterfly mist (Ageratum corymbosum)

·        Black dalea (Dalea pulchra)

Planting your Butterfly Garden

Fall is the best time to plant desert native plants or seeds. The November rains, cooler days and nights trigger germination of seeds, and while the air may be cooler the soil is still warm, encouraging root establishment. This is important for plants to make it through the first summer.

Finding Seed Sources

Many of the plants mentioned above are desert natives, and may be hard to find. Do not harvest seeds or plants from the desert; check online for sources, or find a local nursery specializing in native desert plants.

Alternative fruit trees for the desert

Pomegranate

Growing standard fruit trees in the low desert is challenging. Stone fruits, such as peaches, plums and apricots, require a certain amount of cold (called “chilling hours”) to produce fruit. Even “low chill” varieties may not fruit in a mild winter. Part of the problem, aside from chilling hours, is our fickle winters. A warm spell in January can prompt flowering, only to have the flowers killed by a February frost. And although citrus trees do not require chilling hours, they are high water consumers and need protection from heavy frosts all winter. If you don't want the fuss, here are a few fruit tree alternatives that are less water greedy and still produce tasty fruit. They are also attractive and functional plants, too.

Pomegranates have now become quite the rage because of the fruit's health benefits. The fruits are quite expensive in stores, so what a great bonus to grow your own! Even better: pomegranates start producing fruit even where they are only a couple feet tall.
Pomegranates do very well in the desert. They love our alkaline soil. They are very drought tolerant, but do need a little extra water while they are fruiting so the fruits don't split open. They make a lovely large shrub or small tree. Their flowers attract hummingbirds, too. Keep in mind they are deciduous. 

Another plant that does quite well here is the Pineapple Guava. This is an attractive, evergreen shrub or small tree with gray-green leaves that are white on the underside. The flowers, which are edible, are a pretty pinkish to white with distinctive red stamens. The fruit ripens from late fall into December. Don't pick them off the tree; they are only ripe when they fall to the ground. The fruit resemble kiwis, but are tart, and taste a bit citrusy.

Loquats are another option. This evergreen tree of small stature is unusual for a desert plant since it has very large leaves. These leaves are covered with fine hairs that protect it from the heat by reflecting off the intense suns rays. Loquat fruits ripen in the spring, and taste somewhat like apricots. It is also somewhat drought tolerant.

If you just gotta have oranges, why not try the Kumquat? The Kumquat is the citrus industry’s attempt at creating a cold hardy citrus tree. While they didn’t catch on as they’d hoped, they are available for purchase. Kumquats are more cold tolerant than regular citrus trees, but will still need protection if temperatures drop into the 20’s. The fruits are tiny, an inch or so long, and should be eaten without peeling, as most of the sweetness is in the peel.

Do you really need to know those Latin plant names?

Acacia constricta (Whitethorn Acacia)

Have you ever wondered what those tongue twisting Latin plant names mean? Although they may look daunting to pronounce, they actually have a rhyme and reason. Here are a few examples of how to decipher the scientific name of plants and why it pays to know.

Plant names are based on genus and species, specifically referencing a certain plant and recognized everywhere as that plant. Common names are confusing and not accurate; a plant may have several different common names, but only one scientific name. This can have you walking out of the nursery with the wrong plant.

Latin names are descriptive of the plant’s appearance, or in some cases where it comes from. Mexicana in the name means it is from Mexico. Whitethorn acacia, one of our native plants, is called Acacia constricta. It is in the genus Acacia, and the species name, constricta, references the seed pods with deep constrictions between the seeds inside, separating each seed into a chamber.

Many Latin names give you an indication of flower color. For example, plant names with the word alba or albus means they have white flowers or other plant parts. Incanus means gray or hoary; like Poliomintha incanus, which is hoary mint, one of our desert native shrubs. Plants with yellow parts will have names such as citrinus, corceus and luteus.

It pays to know the Latin name over the common name especially when you are selecting plants a bit out of the ordinary. That way you are sure you are getting the exact species you think you are.

Do you really need to know those Latin plant names?

Acacia constricta (Whitethorn Acacia)

Have you ever wondered what those tongue twisting Latin plant names mean? Although they may look daunting to pronounce, they actually have a rhyme and reason. Here are a few examples of how to decipher the scientific name of plants and why it pays to know.

Plant names are based on genus and species, specifically referencing a certain plant and recognized everywhere as that plant. Common names are confusing and not accurate; a plant may have several different common names, but only one scientific name. This can have you walking out of the nursery with the wrong plant.

Latin names are descriptive of the plant’s appearance, or in some cases where it comes from. Mexicana in the name means it is from Mexico. Whitethorn acacia, one of our native plants, is called Acacia constricta. It is in the genus Acacia, and the species name, constricta, references the seed pods with deep constrictions between the seeds inside, separating each seed into a chamber.

Many Latin names give you an indication of flower color. For example, plant names with the word alba or albus means they have white flowers or other plant parts. Incanus means gray or hoary; like Poliomintha incanus, which is hoary mint, one of our desert native shrubs. Plants with yellow parts will have names such as citrinus, corceus and luteus.

It pays to know the Latin name over the common name especially when you are selecting plants a bit out of the ordinary. That way you are sure you are getting the exact species you think you are.

Are you under or over watering your landscape plants?

Growing plants in the desert is challenging all the way around; from the heat to cold to minimal rainfall, getting plants to thrive can be frustrating. If you are puzzled as to how to tell if you are over or under watering your landscaping in the desert southwest, here are some guidelines.

It is frustrating to try and figure out what your plants want, as by the time they show symptoms in many cases, it’s too late to save the plant. Do not wait too long, however, or you may lose most of your plants.

Under and over watering symptoms often overlap, creating even more frustration. Evaluating symptoms carefully, however, will guide you in the right direction.

Under watering symptoms include loss of plant vigor, wilting, yellow leaves, leaf curling or drop, pest attack, stem and branch dieback and eventual death. Over watering symptoms include leaves yellowing, leaves smaller than normal, chlorosis (both iron and nitrogen), slow decline, soil-borne pathogens, and eventual death.

If your home was built within the past few years, chances are pretty good your irrigation timer is set for initial planting. After the first few months, the irrigation system should have been rescheduled. In this case, almost guaranteed your plants are being over watered. If you are a minimalist and either don’t have an irrigation system or try to water by hand, chances are pretty good you are not watering enough or deep enough.

Although desert plants are drought and low water specialists, most do need some periodic irrigation to look their best. Just don’t kill them with kindness (water).

It's time to adjust your irrigation schedule

As we approach November, it’s getting close to time to reset irrigation controller. Why should you bother? Wasting water never makes sense. The average home in my community uses 200 gallons per day. It may not sound like much, but add that up over a year, and that’s 73,000 gallons. Forty percent of that is typically for outdoor watering. That’s nearly 30,000 gallons per year. With the water situation here at critical levels, it makes no sense to water plants when they don’t need it.

Days are getting shorter and cooler, so plants require less water. Irrigation of desert adapted and native plants can go to once a week starting in late October. For well-established native plants (at least 3 years old) you can back off to twice a month.

There is one caveat to this, however. The only way you can change your watering schedule is if you have been watering correctly from the start. This means deep watering so the entire root system gets a good soaking. If you have been engaged in shallow watering, the root system will not be as drought tolerant, and the plant may show signs of stress if you back off.

So how to change this? Start watering your plants deeply and slowly, and over a growing season (through next summer) you will be able to adjust your irrigation in the winter months to save water. The truth is, a vigorously growing landscape plant is not happier. Studies have proven moderately stressed plants, plants that are not watered and fertilized regularly, are less prone to insect pests and disease.

Planning a new garden: location, location, location!

So you want to start a garden. Congratulations!

First up, you’ll need to consider orientation, soil type and physical location. Preferably you want an area that is not too rocky and relatively flat. It should be near the house, but not too close as the garden is not always picturesque and can be odorous if you are using steer manure. You DO want it near enough that it is convenient to bring produce into the kitchen. The garden will need at least 6 hours of sunshine per day and afternoon shade, whether you take advantage of a tree or building, or are planning on putting up shade cloth.

The next consideration is size. If you are limited for space, make it as large as you possibly can as you will want to be able to rotate your crops; especially tomatoes and peppers, which are susceptible to multiple diseases and should not be planted in the same place for at least 3 years. 

Raised beds are an option if your soil is just too rocky, or if caliche is a problem in your area. Keep in mind several things. Raised beds dry out quicker so you will be watering more often, you will have to import top soil to fill them (and make sure it really is top soil as otherwise you will end up with excavated soil that has no nutritional value), you will have to be careful about using treated lumber for the edges as it contains arsenic. Concrete blocks will leach lime into the bed, and plants don’t like that either. You will also probably end up turning the soil by hand, as it is difficult to rototill inside a raised bed. My preference is to just work with what you have, but there are cases where raised beds are the only option.

The garden will need to be fenced against rodents and snakes, and if you are in a very rural area also javalina and deer. Even if you have a fence or wall, keep in mind that ground squirrels can climb walls and ground squirrels, rabbits and javalina will dig under fences to get after your garden bounty. Some snakes can climb fences and walls, so they need to be tall enough to discourage this. Snakes can slip through a 1” opening, so you will need to secure the gate openings as well.

If you live in an area where rabbits, ground squirrels and snakes have the potential for being a problem, you will need to erect a fence at least 4’ tall. Use fence with 2” x 4” openings, and add 3’ tall ¼” hardware cloth or ½” chicken wire to the fence, burying at least 12” underground, and bending at least a few inches of the bottom into an L shape, to deter rodents from digging under. If javalina are a potential problem, you will need to reinforce the bottom of the fence with barbed wire. If deer could be a problem, your fence will need to be 8’ tall.

Also keep in mind where you will be storing composting materials. If you plan on obtaining large quantities of animal manure or storing straw and other composting supplies, you will need a place where a vehicle can access, and close enough to the garden so you aren’t making tons of wheelbarrow trips. You also don’t want it to offend the neighbors, so try to keep it out of sight, if possible.

Planning a new garden: location, location, location!

So you want to start a garden. Congratulations!

First up, you’ll need to consider orientation, soil type and physical location. Preferably you want an area that is not too rocky and relatively flat. It should be near the house, but not too close as the garden is not always picturesque and can be odorous if you are using steer manure. You DO want it near enough that it is convenient to bring produce into the kitchen. The garden will need at least 6 hours of sunshine per day and afternoon shade, whether you take advantage of a tree or building, or are planning on putting up shade cloth.

The next consideration is size. If you are limited for space, make it as large as you possibly can as you will want to be able to rotate your crops; especially tomatoes and peppers, which are susceptible to multiple diseases and should not be planted in the same place for at least 3 years. 

Raised beds are an option if your soil is just too rocky, or if caliche is a problem in your area. Keep in mind several things. Raised beds dry out quicker so you will be watering more often, you will have to import top soil to fill them (and make sure it really is top soil as otherwise you will end up with excavated soil that has no nutritional value), you will have to be careful about using treated lumber for the edges as it contains arsenic. Concrete blocks will leach lime into the bed, and plants don’t like that either. You will also probably end up turning the soil by hand, as it is difficult to rototill inside a raised bed. My preference is to just work with what you have, but there are cases where raised beds are the only option.

The garden will need to be fenced against rodents and snakes, and if you are in a very rural area also javalina and deer. Even if you have a fence or wall, keep in mind that ground squirrels can climb walls and ground squirrels, rabbits and javalina will dig under fences to get after your garden bounty. Some snakes can climb fences and walls, so they need to be tall enough to discourage this. Snakes can slip through a 1” opening, so you will need to secure the gate openings as well.

If you live in an area where rabbits, ground squirrels and snakes have the potential for being a problem, you will need to erect a fence at least 4’ tall. Use fence with 2” x 4” openings, and add 3’ tall ¼” hardware cloth or ½” chicken wire to the fence, burying at least 12” underground, and bending at least a few inches of the bottom into an L shape, to deter rodents from digging under. If javalina are a potential problem, you will need to reinforce the bottom of the fence with barbed wire. If deer could be a problem, your fence will need to be 8’ tall.

Also keep in mind where you will be storing composting materials. If you plan on obtaining large quantities of animal manure or storing straw and other composting supplies, you will need a place where a vehicle can access, and close enough to the garden so you aren’t making tons of wheelbarrow trips. You also don’t want it to offend the neighbors, so try to keep it out of sight, if possible.

A primer on biological insect controls

Bt works wonders on the tomato hornworm

There are a number of products on the market that advertise they are biological insect controllers, and it is important to understand how some of these products work. Just because a product is made from natural ingredients, does not mean it is necessarily non-toxic or safe for the environment. 

For an organic garden, you need to keep in mind what your priorities are. If you do not want to use any pesticides what-so-ever, then handpicking bugs and barriers (such as floating row covers) may be your best options. There may come a point when you need some help, and there are products out there that can do that for you.

BACILLUS THURINGIENSIS

I am a big proponent of Bt (Bacillus thuringiensis and its counterparts) as it is totally biodegradable, non-toxic to humans, pets, fish and birds. It affects the digestive system of caterpillars when they eat the treated plant. Although it will also kill caterpillars of butterflies, they rarely feed on your vegetable garden plants. To be safe, don’t spray ornamental flowers that normally attract butterflies. Another reason I consider Bt a really good product is that you can use it as a preventative. It is a “non-contact” insect killer, which means the insects don’t have to be present and you don’t have to spray the actual bug. Bt can be used on products sold as organic.

ROTENONE

Although this insecticide is made from natural ingredients, is biodegradable, but it is not non-toxic. It is a contact insecticide (you have to actually spray the insect to kill it) and is not allowed to be used on produce to be sold as organic.

PYRETHRUM

This too is a synthetic insecticide even though it is made from Chrysanthemums.  It is highly toxic to fish and honey bees. It is a contact insecticide, and considered to have a low toxicity to humans. 

SAFER INSECTICIDAL SOAP

This product is made from natural oils and animal fats and is effective against aphids, scale and other soft bodied insects. It is considered non-toxic to humans and approved for use on organic produce. The downside is if you apply it in really hot weather in a sunny location you could damage your plants. 

Critter proofing your garden

My critter proof fence.

There is nothing worse than spending a lot of time and energy into preparing your garden soil, planting seeds and seedlings, and nurturing everything so you will have a good harvest only to have ground squirrels wreck havoc.

Birds are easier to deal with, since bird netting will keep most of them at bay. Fencing keeps out most animals like skunks and rabbits, especially if you bury the fence 8 to 12 inches so they can’t dig under. But ground squirrels, as cute as they are, are far more industrious and determined that most other problem critters.

Poisoning wildlife serves no real purpose other than upsetting the balance of nature. If you rely on poison you risk poisoning predators such as hawks, owls, coyotes and bobcats as well as the squirrels, and will spend a fortune. Squirrels are very prolific because they are darned low on the food chain.

There are also many repellents on the market touted to keep animals away from your plants. Some gardeners swear by pepper spray, Lifebuoy soap, certain aromatic plants, and mothballs, to name a few. However, my experience has been that nothing works other than a physical barrier. I’ve seen rabbits eat plants coated with cayenne pepper, so the fact is, you can’t rely on these products.

If you are just starting a garden and know ground squirrels live in your area, build a defense system early since once they figure out you have goodies planted, they try harder to get in. It does not matter how tiny the openings are in your fence, ground squirrels are not only adept at digging under fences, they also climb over fences. A 4 foot tall fence is nothing to these acrobats.

A non-climbable fence is a more expensive option than any wire fence, including chain link. What is considered non-climbable? Think something slick, such as corrugated metal or sheet metal. Yes, it will look ugly. But yes, it will work. You will need sturdy posts set in concrete, however, so it does not blow over in high winds.

Another option is to cut metal and attach to your existing fence, provided the openings on your metal fencing are no larger than ½ inch squares. The non-climbable portion should be placed at the top of the fence since they most likely will not be able to leap over the entire 4 feet.

Your fencing not only needs burying, but it should be in a L shape so they cannot dig under. An alternative is to lay 2 foot tall hardware cloth on the ground all the way around your fence, securing with U-pins or rocks.

Check your fencing regularly, since they are looking for weak spots every single day.

Sound like a lot of work? Yes it is. But having home-grown produce is worth every minute of it.

The basics of building good garden soil

My simple worm bin

Although it seems like desert soils would not be suitable for vegetable gardening, the reality is all they lack is water to be productive. However, to make these soils more water efficient, and to replenish nutrients used in growing plants, amendments are necessary for all types of desert soils. I will only be discussing organic methods in this section.

Sandy soils are the most challenging and ‘needy’ when it comes to amendments.  The addition of organic matter is necessary to help these soils maintain a moisture level conducive to growing healthy plants. 

Clay soils hold moisture far better than sandy soils, but if the clay is very heavy it can hold too much water and can cause root rot and other problems. The addition of organic matter in this case is to provide better drainage and aeration of the soil, both essential to healthy plant growth.

The best types of amendments come from animal sources. Although chicken manure, bat guano, fish emulsions provide nitrogen to feed plants, they do not contain other essential nutrients (such as potassium, potash, calcium and carbon to name a few) which is depleted from the soil after every growing season. The goal is not just to feed the garden soil, but to create a soil structure which supports healthy plants, reduces the amount of water needed, increases beneficial soil microbes, attracts beneficial insects and soil building organisms such as earthworms. The best way to tell if your garden soil is being tended to properly is the appearance of earthworms. You can’t just add them to your garden and hope they will multiply. In most areas of the country, “if you build it, they will come.” However, I’ve been informed by the University of Arizona this is rarely the case in the desert as earthworms are not endemic here. So what’s a gardener to do? Make an earthworm bin and use their castings. It’s much easier to maintain a stable environment in a bin than it is in your garden.

Adding animal manures such as from steer or horses also provides organic matter that helps sandy soil hold moisture and improves drainage in clay soil, providing low levels of nitrogen to feed the plants. Never add clay soil to sandy soil. This makes cement, which is certainly not the goal here! Also important is adding straw. Although straw does require nitrogen to break down, adding it along with the manure several months before planting will start the decomposition process and also allow the manure to ‘age’ before planting. This is important as some manures contain high levels of salt (from feed) that needs to be leached out prior to planting to avoid burning new plants. I purchase both steam sterilized steer manure and straw way ahead of my needs, and allow it sit for at least 6 months or longer before using. Horse manure can contain weed seeds and sometimes Bermuda grass (which you definitely don’t want in your garden), so be careful of using unless you have the time to sterilize it yourself, by placing heavy weight clear plastic over a pile and letting it cook in the hot summer sun for a few months. This will kill off most seeds.

Of course, don’t forget compost. If you aren’t composting and you want a garden, you need to start. Compost bins can make life easier, but are not necessary. I’ve always composted directly in my garden, as turning piles and keeping them moist is just too much work. I bury kitchen scraps (vegetable and fruit trimmings, egg shells (in moderation), and other plant matter (no meat, dairy or fish) in between rows. That’s it! Nature will take its course.

Diagnosing mysterious plant problems

Velvet mesquite, one of our best native trees

Nothing is more frustrating than putting a lot of hard work and spending tons of time caring for landscape plants, only to have them succumb to some kind of disease or pest. If your plant is looking a little sickly, here are some common symptoms to look for to help you diagnose the problem, along with fairly simple solutions.

Is your plant wilting? Obviously, the first thing that comes to mind is lack of water. If you have ruled out your plant being thirsty, there are a number of other problems that can cause wilting. The reality is over watering can also make leaves wilt, because the roots are rotting. Make sure your plant is not getting too much water. The soil needs to dry out in between waterings so the roots can obtain oxygen. Yes! Roots need to be able to breathe.

Texas Root Rot is prevalent in the southwest, and causes significant root loss in short order. By the time you see wilting, it is dead. Plant resistant species, but never in the same spot. Which plants succumb to Texas Root Rot? Here’s a sampling:

Ash

Elm

African Sumac

California Pepper

Roses

Xylosma

Silk Oak

Bottle Tree

Roses

All stone fruit trees (peaches, plums and apricots)

All nut trees

Notice not one of those is a desert native. This is one of the many reasons why I recommend planting natives.

Some insects can cause wilting as they water out of the leaves. Look on underneath leaves for sucking insects like aphids and mites. If you see them, spray off with the garden hose. No chemicals needed.

What about leaf color changes that aren’t normal for the species? Are the leaves turning yellow? In some cases, this could be nitrogen deficiency. Planting natives usually means fertilizer is rarely warranted since they are adapted to the soil. If the plant is not a desert native, and the leaves are yellow with green veins, this is a sign of iron chlorosis, caused by a deficiency of iron in the soil, or by high pH soils. Soils with high alkalinity prevent the absorption of iron. Treating is expensive and labor intensive. It is better to choose plants that grow in alkaline soils.

Also keep in mind, that early leaf coloration is often caused by drought. Stick with desert natives with low water use requirements.

Is your plant just sitting there and not growing? One of the deadliest thing that can happen to your new tree is planting too deep. If the planting hole was deeper than the root ball, chances are it sunk into the hole and dirt has gathered around the trunk. You can try removing soil that is up against the trunk base. This might work, and worth a try. Next time remember to never dig a hole deeper than the root ball.

Many times plant problems arise because the species is not suitable for our desert climate and soils. Choosing desert native plants is a smart way to avoid many problems and have greater success with minimal effort.

Those pesky and destructive whiteflies: what's a gardener to do?

If you see a cloud of white insects flying around your vegetable garden, unfortunately this means you have the dreaded whitefly. They are especially attracted to lettuce, and are a huge problem for Arizona lettuce growers in the winter. They also attack tomatoes, peppers, cabbage and the foliage of carrots, and have a liking to herbs like parsley as well. They are a sucking insect, and can kill the plant within a short amount of time. Since they love dry, dusty conditions, the desert is a perfect climate.

They are dreaded because they multiple incredibly fast and are very difficult to control naturally. Although some experts recommend using beneficial insects for a natural control, this method is not particularly successful in the desert environment because conditions are just not that favorable for many beneficial insects to stick around and do any good. You can try sticky traps, which need replacing as they fill up with insects. Barriers such as floating row covers work, provided you get them on before the whitefly sets eggs on your plants, but this does not work once temperatures rise into the mid to upper 80’s because it just plain gets too hot under there.

Since whiteflies love dry, dusty conditions, your best bet is to hose off plants often. If you have one plant they particularly like, it may be worth it to sacrifice that one plant to reduce infestation of the others.

Common problems with cactus and succulents

Damaged by the Agave Snout-nose weevil

Cactus and succulents are relatively problem free, as long as growing conditions, soil, drainage and sun orientation are correct for the species. Always make sure you are purchasing plants are suitable for both the heat and cold. Not all of these plants can handle the brutal low elevation summer heat, or temperatures dipping into the teens. When in doubt: Plant natives!

Cochineal scale is relatively common on prickly pear and cholla. It is evidenced by cottony-like spots on the pads and stems. This insect sucks out nutrients. If left without treatment, it will eventually kill the plant. Control is simple by using repeated hard sprays of water. It’s important to catch this early, however. If the entire plant is covered with the white substance, it’s unlikely you’ll ever be able to get rid of it. It’s been to remove and replace the plant. As a side note, the female of the insect that causes the white cottony mass is the source of a red dye known as cochineal red. The red dye is used in clothing and candy, so if you are vegetarian, think twice about eating candy dyed red!

The cactus longhorn beetle attacks some columnar cactus and prickly pears leaving chewed areas on the uppermost parts. It is identified by very long antennae, as long as the beetle itself. Hand picking is considered the best control method, so you’ll need to be vigilant. The larvae will eat the inside of the plant, so they are hard to detect and control before the plant is dead.

Sahuaro rot (bacterial necrosis), is an infection caused by a number of things. It can result from sunburn, injury (including transport to planting site), frost damage, too much water and poor drainage. Bacteria spreads inside the plant before you notice what is happening. When a black, odorous liquid oozes out of the plants epidermis, it is too late to save. If this appears on an arm, removal of the arm may save it, but it must be caught before the rotting spreads into the main stem.

And what about those holes in sahuaros made by birds? Birds and sahuaros have lived harmoniously together for centuries, so trust me, the sahuaro will be fine. Those holes, usually made by woodpeckers, will later become homes for other critters, including bats and the tiny pygmy owl.

Some agave species are attacked by the agave snout-nose weevil. You’ll know you’ve got them if the leaves of the agave are laying flat on the ground. This insect prefers stressed plants (think thirsty, overwatered, too much sun, too little sun, poor drainage, temperatures too hot or too cold) and seems to prefer the Century Plant, one of the largest of the agave species. Infestation is hard to detect, and by the time the plant wilts it is too late. Remove, dig up the weevil, and kill it before replanting.