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Desert Garden Maintenance Ideas for May

May is a stunning time of year in our desert gardens! Native plants in our landscapes are flourishing! The weather is warm, but we usually haven't reached the consistently scorching temperatures yet. While we're no longer in our planting season, there's still an opportunity to tackle minor yard projects before the full force of summer heat arrives. Additionally, this is an ideal time to venture into the higher elevations and foothills. The foothills tend to be a bit cooler, prolonging their blooms, while the higher elevations are beginning their summer bloom.

Topics covered: Planting, Pruning, Flowering, Vegetables, Irrigation, Pests, Weeds, and Fertilizer


In the desert, we used to plan for our major pruning in October and  February. As we learn we've realized that it is best to not do major jobs in the spring. Spring is when our wildlife is most active and nesting. By pruning our trees and shrubs we are removing their nesting sites and shelter.

You always want to be looking at your plants though and only trimming problem areas. Is there a branch in your pathway or do you have a dead branch that needs to be taken out? At this time of year, you want to check for leggy growth that needs pruning back and determine if the plant is overgrown. This keeps you from having to do as much in the fall and corrects issues before they become major problems. If you have to regularly prune your plants you should look at why. Trees should not need to be pruned yearly. Shrubs left in their natural shape only need an occasional snip here or there. Are you watering too much? Is the plant in the wrong place? And most importantly, you want to always check for nesting animals before you prune!


If the plant is actively flowering, wait until October. If I need to "clean up" an area I don't trim all the flowering plants in that section. I will make sure to leave blooms for the animals.


Most importantly, if you can tell it's been pruned, it was done incorrectly! Your job is to help the plant maintain its natural shape not force it to be the shape you want.


If the plant is a summer grower, like a mesquite, I recommend waiting until after its growth spurt and prune in October. 

For spring flowering shrubs like Sennas and Texas Rangers, once they have stopped, you can thin them lightly to control size. 

Once it is hot, we can cut back too large cacti. Use a sharp saw or break at the joint. If using a saw, cut at an angle to prevent water from pooling in the cut.


The desert will reach is still in full color this month! Desert Marigold, Desert Milkweed, California Poppy, Evening Primrose, Globemallow, and especially cacti will be in bloom!

You want to continue to deadhead some flowers to promote a prolonged bloom. I leave the majority of my spent blooms as seeds for wildlife.

Collect seeds for next year as soon as the seedpod begins to turn brown or dry out. Store in a paper bag and allow to dry out for a week or two in a dry shady spot. If you want a more natural landscape, allow the seeds to drop naturally.

Pests, Weeds, and Fertilizer

1. Preventative Pest Control: Embrace drip irrigation, a method that keeps plants healthy by watering them from below, minimizing disease by avoiding wet leaves. Healthy plants are naturally more resilient, hosting fewer pests. 

2. Understand Your Foes: Identifying your garden's foes is essential. Not every bug is a threat, and understanding the natural life cycles of both plants and animals in your garden helps differentiate between normal processes and actual threats.

With warm temperatures, come aphids Luckily they are very plant-specific. Certain aphids only like certain plants and won't bother others. Before you decide what to do about them, decide if they are actually causing a problem.

Example: on our milkweed, aphids are a natural part of their ecosystem along with milkweed bugs. They aren't good or bad, They just are. They attract beneficial insects like ladybugs and lacewings to the garden which is a good thing.

Another common thing we start to see as the weather heats up is perfect circles cut in the leaves of plants. This is usually caused by one of our native bees the Megachilidae or leaf-cutting bee.  We start to see them when the temperature is consistently above 75 degrees. This is not a pest but one of our native pollinators! The leaf-cutting bee uses its legs to cut the circles in the leaves - they do not eat it. So when you spray an insecticide on your plant to stop this behavior you are not doing anything but needlessly spraying chemicals on your plant and potentially harming things you are trying to attract.

You might also see some caterpillars nibbling on your plants. Before you start spraying or picking them off, find out what they are. Various native caterpillars are out munching on their host plants. The plants and caterpillars need each other. The plant supplies the caterpillar with food and the caterpillar gives the plant a needed pruning!

Have you seen a white frothy foam on the new growth of your plants? This is protection for the nymph of the spittlebug. They are relatively harmless but you can remove them with a strong jet from the hose.

One of our native bees, the Lots of native bees are active now. They are excellent pollinators and should not be considered pests!

3. Timing: The good news is that most "bad" bugs don't like the summer heat and will soon be gone. In my opinion, the best thing to do in most cases is to wait and let nature take care of itself.

4. Gentle Intervention: At the first signs of infestation, opt for the least invasive control methods. A powerful jet from your hose or a soapy water solution can work wonders and is gentle on your garden's ecosystem. Timing matters too; treat infestations at dusk when bees and butterflies are at rest, ensuring their safety.

When I find the aphids are causing a problem on, say, a young plant that can't handle it, I will spray them off with a strong stream of water.

You can also put on gloves and run your hand up the plant basically squishing them. Some people use q-tips with alcohol or alone. Most times if you really watch your garden and have planted appropriate plants, pests will work themselves out.

Treat the first signs of mealy bugs though with a q-tip dipped in alcohol. A large infestation is difficult to control without chemical intervention.

5. Weed Management: Weeds are insidious foes, so regular weeding is essential to prevent their spread. As the weather warms and days get longer, weed growth speeds up so be vigilant. If you pull the weeds BEFORE they flower, this proactive maintenance saves you from hours of labor later on. Flowers = seeds. Again, adjusting your irrigation and checking for leaks will decrease the amount of extra water available for weeds to germinate.

Continue to keep an eye out for Sahara Mustard. It is probably brown and dry now. It is an incredibly invasive weed If you have this it's important to dispose of the flowers and seeds.

Spurge weed, (Euphorbia maculata) is popping up now that the weather is warm. Once you have an infestation of this it is difficult to get rid of it. Hand pulling, making sure to remove the tap root, and the use of thick mulch to starve the seedlings of light are the most effective removal methods in my experience. Use gloves when handling spurge. The milky sap can cause irritation in some people.

6. Fertilizing Strategy: While desert plants don't require regular fertilization, they can benefit from a generous layer of mulch (about 3-4 inches). This keeps the soil cool and reduces water evaporation while providing essential nutrients. Consider allowing your leaves to fall and collect naturally. Various sized rubble is another excellent natural looking mulch. The many-faceted sides reflect the sun's rays keeping the ground cool. 


 Squash, corn, Armenian cucumbers, and melons should be doing very well now. 

Do not fertilize winter growing herbs until fall.

To extend your tomato and pepper harvest, add shade, mulch, and water deeply but less frequently. You want the roots to go down deep into the cool soil where it takes longer to dry out.


Our planting season begins in September/October and ends in March. Planting in the fall our plants have lots of time to establish themselves before the heat of summer hits. Up to 80% of the yearly root growth occurs in the fall when the days are shorter and the temperatures are cooler. The later in the year we plant the more water we need to use to establish them and the more care they need. Plants need at least 6-8 weeks to reestablish their roots before the extreme heat of summer hits. 


Continue to increase your water as the temperatures rise. If you do not already have one, consider a smart timer. Most local water agencies offer incentives or even free ones!

If you are not on automatic irrigation and are hand watering, now is when you want to do deep watering in preparation for the rapid spring growth. Fill your basins and allow the water to slowly soak in. For trees and large shrubs, you want saturation 2-3 feet deep. Other plants need saturation 1-1.5 feet deep depending on the size.

If you leave for the summer, make sure to check your irrigation system before you go for leaks, clogged emitters, etc.

Refresh the water basins and mulch around your trees and plants before the summer heat.

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