May 2024 in the Garden

May Day is nigh! Time to get your garden and landscape ready for the summer ahead.  Sadly, for 2024, the long range weather forecasts say that it is going to be a hot dry one.

May In General

In the Desert Elevations – tasks in May revolve around making sure the water system is working.

In all elevations, it’s time for fertilizer to encourage healthy growth for the tough summer ahead.

gardening-with-soule-water-southwest-irrigationIrrigation System Tune Up Time

Irrigation systems require checking and tune-up on a regular basis. Some tasks should be done once per month, some should be done quarterly – as the seasons change.

Tune up irrigation system now with these tasks.
* clean filter – knock it out and soak it in white vinegar
* flush out debris – to take off all end caps and run the system to flush out debris.
* check timer settings - change from spring to summer program.


Walk the lines and check the system for leaks or lost emitters, at least a monthly chore.  In my javelina infested yard – I have to walk the lines every time I turn on irrigation. They are thirsty and their razor tusks slice through irrigation lines like a hot knife through butter. They never get much to drink because the irrigation is not running– but hope springs eternal in their tiny black hearts and they bite through in several places.

Fertilizer Tasks for May

With a dry summer expected do have care with fertilizer. You do not want to encourage large or rampant growth – just some healthy growth.

The best fertilizer would be a layer of well composted material laid over the feeder roots (see below) and watered into the soil. Next best is some store-bought natural fertilizer, like bat guano. Least best is an artificial fertilizer made in a lab and brightly colored.


As I write this I went to check for links and discovered that as I am rebuilding after the hackers I have not yet put up my “Fertilizer 101.”  Look for that in the weeks ahead. If you are signed up for my new Substack newsletter I’ll let you know the week the information is posted. If you signed up for the old newsletter – no worries – you are still signed up and if you did not get one yet – please check your spam.

How Much Fertilizer?

We do want to help our plants, but in this arid environment it is easy to over do it.     When in doubt use half-strength fertilizer and do it again in two weeks.

* Fertilize established grass lawns with a high nitrogen fertilizer. Wait at least 2 weeks since last application.
* Fertilize roses every two weeks through bloom period.
* Fertilize deciduous fruit trees (almond, apple, fig, pomegranate, etc) with a fruiting fertilizer any time during the month.
Do NOT even “a little bit extra” – it can easily cause fruit drop! Read and follow label directions.


* Apply soil acidifier to alkaline-induced chlorosis plants.
* After mid-May, fertilize evergreen fruits (citrus, Natal plum, banana, etc.) with a fruiting fertilizer (high in phosphorous). I fertilize on Memorial Day because the next dose is on Labor Day and it’s easier to remember. Citrus Care

* After mid-May, fertilize established palms with a high nitrogen fertilizer. If they are date palms, and you want dates, use a fruiting (high phosphorous) fertilizer instead. I fertilize on these on Memorial Day as well.  Palm Care

Avoid Fertilizer on Legumes

No fertilizer for the plants in the Legume or Pea Family, this includes acacia, mesquite, palo verde, and all their kin. If you give them fertilizer you can destroy their healthy “gut bacteria.” Well, they don’t have “guts” – but just like humans, plants do have a specialized area where they absorb the nutrients they need. This place is the feeder roots. Feeder roots eventually turn into anchor roots – but today we are just concerned with the feeders.

The dashed outer circle is where the feeder roots are around the outside of the tree or shrub.

In the case of the legumes those feeder roots depend on a healthy relationship with very specific bacteria so that they can absorb the nutrients they need out of the air in between the grains of soil. (Trying to give you facts without all the cool science nerdy stuff. That’s a topic for another post.)

Legume pods developing. Image courtesy the Desert Legume Program (DELEP)

Is This a Legume?

How do you know what is a legume? Look for pea-podish structures. Mesquite, Mexican bird of paradise, Texas ebony, fairy duster, Lysiloma, and so many others that make pea-like pods. It’s a really big family. Many of them are wonderful for our landscapes.

When in doubt, Wikipedia can help tell you what family a plant is in. Garden nerds like myself are constantly adding horticultural data to the site. Or ask me below in the Comments section!

The Peace rose. April 29 was National Peace Rose Day. Why this day? Hint: April 29, 1945.

But – My Plants are Next to Legumes!

Yep.  Happens to all of us.  Want to fertilize roses but they are right next to mesquites?  Great question! Here is where we get back to the “feeder roots” and that picture I put earlier in this post.  It’s a wide circle!  A big tree has many tiny feeder roots. If a few in one area can’t feed the tree, there are still many others that can do the job. If your flowering plants are near or under a legume – this is the place where it is doubly important to use a natural fertilizer (not lab made).  Natural fertilizer  will have a lesser impact on the root bacteria.


General Tasks – Anytime in May

If your wildflowers are still blooming – keep watering! My friend Helga often had wildflowers to the end of May in her yard. Just a rain shower from the hose every day.

Add “color” with heat tolerant annuals like sunflower, celosia (cock’s comb), gallardia, and moss rose. More on this topic to come.

Mulch with organic mulches if you haven’t already, especially citrus and vegetables. Even that dyed bark mulch from the big box store is better than rock.

Plant hot season vegetables and herbs, including: amaranth, muskmelon, okra, pepper, squash, tomato, basil, marjoram, oregano, and rosemary. More on warm season vegetables – here.

Plant or transplant cacti and other succulents, such as agaves and hesperaloe – try to do this before the 100’s hit.


Blast spider mites off evergreens with water or spray with insecticidal soap. Repeat as needed at least every other day for 10 days until mite population is knocked back.

Remove spent flowers (deadhead) to prolong bloom on roses and annuals.

Want more bulb flowers next year? Let the leaves of your flowering bulbs become entirely dry and straw-like before trimming off. Planting new spring flowering bulbs is best done in autumn.

As onions are getting ready to harvest, you push the soil back from around the bulb so it grows a layer of protective leaves and stores the sugars better.

After mid- May

Harvest any ready onions, shallots, and garlic.

Watch for caterpillars and treat with insecticidal soap.  Problems are grape-leaf skeletonizers on grapes, skeletonizers on Texas mountain laurel, and orange dogs on citrus (these you can pluck off).

Have care when opening irrigation or water boxes. Such cool shady sites are ideal spots for wildlife. These are king snakes, which will hunt and eat rattlesnakes.

Remember the 3H’s

Don’t forget to be careful out there!

There are 3 H’s for safety in the Southwest.  Hat! Hydrate! Hands!  Here’s my YouTube video on the topic.

Hands? Yes. Never put your hands (or feet) where your eyes have not been first. Not to make you paranoid – but yes, even in walled yards. Snakes can climb rock ledges and garden walls, or go through a rodent hole under a wall.

© Article copyright Jacqueline A. Soule. All rights reserved. You must ask permission to republish an entire blog post or article. Okay to use a short excerpt – but you must give proper credit to Gardening With Soule. You must include a link to the original post on our site. No stealing photos.

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