How to water desert trees

Plants

Desert trees anchor a xeriscape. Such important plants need proper care to look natural and avoid damage. Amazingly one of the best things you can do for a desert tree is NOT water it all the time. Over watering encourages fast, weak growth. When summer windstorms come, a spindly tree loses main branches, potentially ruining its form. My neighbor had an entire tree disappear in a windstorm!

Severely_pruned_mesquite

This Mesquite is nearly full grown, yet has been severely pruned to prevent damage from wind. Watering less frequently would give a better natural form without the need for pruning.

When I plant a young desert tree, I build a basin with edges about 2 feet away from the tree’s trunk. I’ll start by watering the tree every few days for the first week or two while it recovers from transplant shock, then I fill the basin once a week while the tree gets established, about the first year. After a year, a desert tree can live with watering once every 2 to 4 weeks. If the tree seems to be growing slowly, you can increase the water frequency to no more than once per week.

Baby Palo Verde basin

A lush baby Palo Verde tree with a 2 foot basin.

As the tree grows, expand its basin. Once a year in spring you can rebuild the sides of the basin farther away from the trunk. The basin around the tree allows you to give a large drink with each watering, penetrating farther into the soil and allowing the trees roots to grow deeper. Shallow watering encourages shallow roots, which allows the top of the tree to become heavier than the root strength. In order to allow the basin to fully fill, turn a hose on at a trickle and set a timer for an hour, monitoring to make sure your basin doesn’t overflow. Or if your tree is on your irrigation system, you can add the number and flow rate of emitters needed to fill the basin in the time scheduled for your system.

Desert_tree_basin

A larger basin on a more mature desert tree. This basin measures about six feet across and is doughnut-shaped to encourage roots to spread away from the trunk. This tree blew over a few times while young and needed stronger roots.

Once my desert trees have doubled in size or seem well established, they can be watered even less frequently. A few of my trees border a low spot in my yard where water pools when it rains. These trees are not on my irrigation system and I hardly ever water them by hand. The winter and summer rains give them deep drinks which keep them healthy. They usually keep their leaves all season long, so I know they are getting enough water.

Juvenile_Palo_verde

This Foothills Palo Verde has been in the ground about 5 years and no longer needs any irrigation since it borders a low spot in the yard.

When watered appropriately, desert trees grow slower with more proportional shape and stronger branches. Over time they can still grow to mature heights of up to 30 feet, and much more quickly than they would in the desert.

Ironwood leaves die in spring?

Plants

This spring, all four of my young ironwood trees lost their leaves. The leaves turned yellow just as spring growth happened all around them. I thought somehow my trees were dying, though I didn’t see any reason why. About a month after the leaves started dying, I saw new growth. All four trees have now grown new foliage.

While I’m not sure why this happened, I’m glad the trees are still healthy. I found this information at desertmuseum.org:
“Branches that produce flowers often drop their leaves during bud formation, and re-leaf when summer rains begin”

My young trees have never flowered, but perhaps their leaves had remained on the tree long enough to need to be replaced. Ironwoods remain my favorite desert tree due to their size, leaf color, wildlife habitat, and shade. Some day I hope to have a large wildflower area with three mature ironwood trees as the backbone. I’m glad these trees are okay. They grow slowly and would be hard to replace.

Just plant it!

Plants

The weather has been so beautiful…

I had over fourteen plants sitting around in pots. In general, winter is a great time to plant because of the mild temperatures (as long as there is not a freeze right away!) Some of these plants had been at my house for almost a year.

It was time to put them in the ground.

I planted five baby barrel cacti (about four inches in diameter) that I had been hoping would grow better root systems by staying indoors an extra season. I planted three volunteer texas sage and two seedling palo verdes that I potted last fall. I planted a santa rita prickly pear that I grew from a cutting. I planted a small cardon (12 inches tall) that I had been holding on to while deciding where I wanted to put it. I chopped two pieces off my largest deer grass and replanted them.

I’ve been watering the deer grass every other day and the texas sage about twice a week. The rest I’m watering every 1-2 weeks. We’ll see what makes it. The baby barrels have been sunburned before when on my porch, so I hope they’re big enough to acclimate to the yard.

Have you been doing any landscaping this month?

Burned saguaro

Will my saguaro survive being burned by fire?

Plants
Small saguaro

Before

DH went out to burn weeds this morning and wasn’t careful. He says the saguaro got a tiny flame and went up in a poof of smoke. What was a healthy plant yesterday now has burned spines and has shrunken so that the ribs are sticking out. I don’t know if my saguaro will survive being burned. Right now I don’t think it will, but I will update this post when I find out.

Burned saguaro

After

This morning I took another photo. There is some green… is it enough for the plant to survive?

Burned saguaro

2 days later

OK. Realistically, I’ll probably replace this cactus in the fall.

 

6 months later…

Burned saguaro

6 months later

I haven’t replaced it yet. It’s still alive but there is horizontal cracking along the ribs where it has expanded. I think I won’t throw it away. In the spring I may replant it in a less noticeable spot and see if it continues to recover. Poor saguaro!

Killer cactus: my cholla is carniverous!

Plants
Killer cholla eats bird

Killer cholla eats bird

One morning in April I walked outside and saw a fledgling bird impaled on my cholla. I had never heard of this before, but I guess some birds that seek shelter from cholla can also get stuck by them during wind storms. This baby was probably from a nearby nest and just landed in an unfortunate location.

I’ve always thought of cholla as the sharks of the cactus world, but here is proof.

Desert wildflowers and weeds

Plants

Growing wildflowers in Arizona hasn’t been easy. My first year here I bought a native wildflower seed mix, threw it on the dirt, raked it in, and watered regularly for a couple of weeks… nothing.

I did have a couple of Mexican gold poppies come up in the front yard and I begged my husband to not spray them when he sprayed the weeds. From that small patch, I now have a patch of poppies every spring that reseeds. They sprout despite application of pre-emergent.

Mexican Poppy

My third year here, I had one brittlebrush and one Parry’s penstemon sprout, which I guarded and pampered. I sprinkled the seed all around the parent plants. My neighbor also gave me some seed from some desert marigold she had in her yard. Those seeds sprouted that summer, during the monsoon.

This spring I had around 50 Parry’s penstemon plants sprout and five brittlebrush. I now have enough sources of seed to stop worrying about pampering each new plant. The desert marigolds keep reseeding also, so I scatter seed in new areas of the yard.

One note: growing wildflowers exponentially increases the amount of hand weeding. So start with a small patch and know what the baby flowers look like so you don’t accidentally pull them.

Now on to harder and more finicky wildflowers.

Ironwood Trees

Plants

Ironwood trees are one of my favorite landscape trees for Arizona. You have probably seen them before, but because they are not brightly colored, you may not have noticed them. Here are some photos to help you identify the next one you see. The wood from ironwood trees is so dense it sinks in water. You have probably seen little statues carved from ironwood.

Ironwood_carving

Ironwood_youngandfull

This tree has been in my yard for a few years and gets watered twice a month. It’s canopy is green and full, and I have pruned it to have a singe trunk for the first three feet, then split into three main branches. I may raise the canopy in time, but it has plenty of space to grow wide, so I may just let it be. The thorns make pruning difficult.

Ironwood_form

This ironwood in a parking lot in Tucson has a nice form. I like the many trunks and branches with raised canopy.

Ironwood_large

This large tree is probably 25 feet tall. Remember the full size of the tree (30×30) when you plant so that you don’t have to take it out or fight (prune) with it yearly when it reaches mature size.

Ironwood_bush

This tree receives almost daily water and grew into a bush before its canopy was raised. Ironwoods can grow fast if watered frequently, but the form may not be as natural as a slower-growing tree.

Ironwood_native

Here is a native ironwood growing in the desert. The gray-green bark and airy foliage make it less noticeable, but it is a plant worth seeing. Ironwoods provide food and shelter for desert animals and birds. One site estimates that ironwoods are used by 150 bird species. The shade provided by an ironwood tree allows other plants to get a foothold in the desert. Any desert tree that shelters new plants is called a nurse tree.

Ironwood_220yearsold

This ironwood growing at the Arizona-Sonora Desert Museum is estimated to be 220 years old.

Ironwood_blossom

Ironwoods bloom in May with dusty mauve flowers. The tree blooms heavily in alternating years. None of the ironwood trees on my property have bloomed yet, making me wonder at what age or size the tree begins reproducing.

Woolly butterfly bush

Toughest drought-tolerant plants for your desert garden

Plant selection, Plants

In order to maximize the number of plants in your garden without overloading your drip system, you may end up planting things that you expect to survive on their own. Luckily, there are some un-prissy plants that can do this. These survivors deserve a medal, instead of being overlooked and under-appreciated. After all, this is the desert! When I moved to Arizona, the house I bought had been vacant for two years and some of the plants in the yard were still alive. That is the kind of landscaping I want.

Trees

Natives: Foothills palo verde, Ironwood, Joshua tree

Non-natives: Catclaw acacia, Whitethorn acacia, Elephant tree (frost sensitive), Smoke tree.

Shrubs

Creosote bush, Desert holly, Four wing saltbush, Jojoba, Las Vegas buckwheat, Limber bush, Mormon tea, Pink fairy duster, Shadscale saltbush, Warnock condalia, White bursage, Yerba santa

Woolly butterfly bush

Woolly butterfly bush

Wildflowers, agaves, yuccas, others

Bahia, Desert sunflower, Prickly poppy, Variegated century plant, Bear grass, Banana yucca, Our Lord’s candle yucca, Candelilla, Slipper plant, Bush muhly grass, Medicinal aloe

Which cacti are cheap?

Plants

Quick answer: None.

Cacti grow slowly, making them more expensive to cultivate. Optimal growing conditions for a cactus are temperatures of 80 degrees (F) and adequate (but not too much) water. One nursery I visited has a giant swamp cooler for it’s green houses to maintain the temperature at optimum growing through the summer.

Cute baby prickly pear

Answer #2: Small ones.

If you buy small cacti, they are cheaper than large ones. Be smart–buy more small cacti and take good care of them and within a few years they will be as big as the larger ones for sale. I recently found some barrel cacti in four inch pots at a nursery for only $4.25! Anything under $10 is a good price.

Answer #3: Ones that propagate easily.

Prickly pear are cheaper than other cacti because it is easy to make new plants. Some agaves also make pups (baby plants) that grow out from the roots. Agaves that do this are cheaper than ones that don’t. You can probably get some pups from someone who has an agave in their yard, and voila! FREE landscaping!

I recommend getting getting lots of the free / cheap cacti and succulents to jump start your landscape, and then replacing them later on (or filling in some empty spots) with more expensive cacti.

Wrong answer: cacti from the desert.

It is illegal to move (steal) cacti from the desert. Since 1929 it has been illegal to damage native plants on, or remove native plants from, state land without a permit.

But I want some trees and ocotillos! Now what?

Some plants for your landscape don’t come in small sizes, but are foundational to your landscape design. Get the smallest healthy specimens you can find. Trees are worth spending a little more on because they take so long to get large, and are hard to replace.

Ocotillos are difficult. If you get the large, bare root specimens, you risk a low survival rate. I have bought 4 ocotillos so far and only 2 of them survived, even with immediate planting. Small ocotillos grow slowly, and over watering them changes their overall shape (more branching). So you can’t just water them extra to get them to grow faster.

Saguaros are another costly favorite. They are about $30 per foot. Specimens over 4-5 feet tall have a harder time rooting and acclimating to their new spot. I recommend getting a few 1-foot tall saguaros and watering them regularly (every 1-2 weeks). With this frequent water, they can grow 6-12 inches per year. If you are dying for bigger saguaros, buy them after you have put in the rest of your landscape. Spend your money on lots of plants first, then expensive plants last.

Agave pups near parent plant

Columnar Cacti: Saguaros and such

Plants

Large saguaro

Saguaros and Arizona go together like bread and butter. They are the largest cacti in the United States, and iconic plants of the Sonoran desert. Many homeowners would like a token saguaro in their landscape. I would challenge you to take the next step and surround your saguaro(s) with other native Sonoran desert plants so that it looks at home.

Saguaro family

Saguaros dot a hillside in the Sonoran desert.

One unique thing about cacti (including saguaros) is they continue to absorb water no matter how full they already are. Overwatering and a very wet period can cause a saguaro to develop horizontal cracks and permanent damage.

Saguaros in the wild tend to concentrate on south facing slopes. Plant a saguaro in a sunny area in your yard that doesn’t contain standing water during rain storms.