September Gardening Tasks

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summer is beginning

There are some signs that summer is beginning to fade and that fall is around the corner.  The stress that the high temperatures of summer bring has caused many plants to slow down their growth.  

However, the slightly lower temperatures in September bring on a flush of new growth for many trees, shrubs, and succulents in the garden.  I enjoy being out in my garden this time of year and seeing many of my plants rejuvenated.

With the somewhat cooler temperatures, I am now seeing many gardeners venturing outside and taking stock of the condition of their landscape.  Fall is a busy time in the desert garden because it is the ideal time to install many types of plants, which will be discussed in a separate post in early October.

summer is beginning

SHRUBS: I just finished lightly pruning my ‘Rio Bravo’ sage (Leucophyllum langmaniae).  Summer flowering shrubs that are cold-hardy look their best when lightly pruned at this time to help reign in rangy, sprawling growth. This should be only done with hand pruners only.  Do not use a hedge trimmer and shear your shrubs.  They should have a pleasing natural shape when you are finished.  Do not prune back frost-sensitive plants at this time.

summer is beginning

ANNUALS:  Although the local nurseries are abundant with winter annuals, I don’t recommend planting them now.  The temperatures are still quite hot, and there is a good chance that they will not make it.  

In the past when mid-September came, I would load up the truck with 100+ flats of annuals to plant around the community where I worked as the horticulturist.   I would then spent the next four weeks making repeated trips to the nursery to replace dead plants that just could not handle the heat of early fall.  From then on I would wait until October to change out summer annuals and replace with winter annuals.  As a result, we suffered very little plant loss.

summer is beginning

TREES:  Mesquite and Palo Verde trees that are overgrown can be lightly easily pruned back.  Resist the temptation to heavily prune at this time.  January and February is the time for heavy pruning to occur for these trees.

summer is beginning

SUCCULENTS:  Cacti, agaves and other succulent plants do best when planted when soil temperatures are warm, which makes September a great time to install them before cooler temperatures arrive.   Prickly Pear cactus can be pruned back this month if needed.  Problems with agave may show up this time of year. 

summer is beginning

If your agave suddenly collapses, there is a good chance that they have gotten an infection with agave snout weevil.  There is no cure and the agave should be removed, it will be smelly due to the decay the weevil causes – and not just a little stinky.

One of my (least) favorite memories happened years ago when I worked as a horticulturist on a golf course.  One year, we had to remove countless agaves throughout the landscapes due to a large infestation – the smell was awful.  If this happens to your agave, do not plant another agave in the area – use another type of plant instead.

Roses

ROSES:  Roses should be lightly pruned and fertilized this month (see earlier post for details).

citrus trees

CITRUS:  Make sure to fertilize your citrus trees if you have not already done so (see earlier post for details).

NEXT MONTH – get ready for planting and wildflower garden preparation!

Fall Citrus Tree Care

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Citrus trees

In the Desert Southwest, we are fortunate to be able to grow citrus.  In early fall, your citrus tree probably looks like the one pictured, with green fruit that is getting ready to ripen in this winter.

It is time for the third fertilizer application to your citrus trees if you have not already done so.  Mature citrus trees require three applications of fertilizer – around Valentine’s Day, Memorial Day and Labor Day.

Citrus trees require nitrogen more than any other nutrient.  I recommend using a granular fertilizer specially formulated for citrus because, in addition to nitrogen, they also contain micronutrients, (iron, zinc, manganese), that are vital to the health of your citrus tree.  Citrus fertilizer spikes are also an option.

If you choose to use only organic fertilizer for your citrus, there are some natural products available, or you can use composted cow manure, working it into the top few inches of soil and watering it in afterward.

GENERAL GUIDELINES:

– Fertilizer should not be applied to newly planted trees – wait until they have been in the ground for one year.

– Water the soil around the tree before and after you apply fertilizer.

– Follow the directions on the fertilizer bag.  Be sure that you divide by three the annual amount of fertilizer needed by your tree – do not apply all at once!

– When in doubt, apply slightly less fertilizer then you think you need.  You don’t want to over-fertilize and end up with fertilizer burn.  Smaller trees require less fertilizer than larger trees.

– Apply granular fertilizer around the perimeter of the tree, extending just past the drip line.  Work into the top few inches of soil.

– Do not apply a foliar fertilizer when air temperatures are 85 degrees F or above because there is a danger of burning the foliage.

– For mature Grapefruit trees, (over six years old), apply only 1/2 the amount of fertilizer recommended on the fertilizer label because high amounts of nitrogen promote a thick rind (peel).

Get ready to enjoy the fruits of your labors this winter and get ready for March when we will discuss the correct way to prune and plant citrus.

Iconic Desert Tree, The Palo Verde