September in the Desert Garden

September is another transition month in the desert. We feel like the worst of summer heat should be over — but it isn’t.

What To Do in September

Grass

If you plan to over-seed your Bermuda, stop fertilizing. You’ll be over-seeding next month.

If you are not planting a winter lawn, add about 10 pounds of Ironite for every 1,000 square feet.

Trees & Shrubs

If you didn’t fertilize your citrus during August, do it now. Use ammonium sulfate. This last fertilizing will help make larger fruit. Lemons can be picked as needed later in September even though the fruit is still green — lemons will not get sweeter, just juicier. Truly ripened limes will turn yellow. This is a good time to get inside your citrus trees, trim out the water sprouts, and clean out any dead wood.

You may begin planting non-frost-sensitive trees and shrubs from containers. Soil temperatures are still warm enough to help roots establish quickly. After planting, water deeply. Dig a planting hole about three times the diameter of the root ball and no deeper.

Flowers

Prepare flower beds just as you would the vegetable plots, but planting of most flowers should be delayed until mid-October.

Hose off the rose leaves 1–2 times a week to remove dust, spider mites, and potential white flies. Water roses about every three days and apply about five gallons of water to each plant. Prune dead canes and weak top growth, but no heavy pruning.

Some bulbs like tulips and hyacinths need to be chilled in a paper sack in the vegetable drawer of your refrigerator for four to six weeks or they won’t bloom.

Vegetables

The most important step to achieving a successful garden in the Valley is soil preparation. Spade the garden beds to a depth of 8–12 inches, turn the soil over, and break up clods. For each 100 square feet of garden area add 2 pounds of 16-20-0 ammonium phosphate, 5 pounds of sulfur, and 5 pounds of Ironite. Spread 3–6 inches (eight to ten two-cubic-foot bags) of compost, forest mulch, or steer manure. Mix all this together, water it well, and when the soil has dried to just moist, you are ready to plant.

If you grow onions, use gypsum in place of sulfur because sulfur makes onions strong and hot.

If your tomatoes and peppers are still alive, trim them back to 18 inches. Remember the root zone is as large as the foliage, so sprinkle one-half cup of ammonium sulfate (21-0-0) and Ironite on moist soil over the entire root zone.

As temperatures drop below 100 degrees, seeds of cool-season crops can be planted. These veggies can be directly seeded in the garden later in the month: beets, celery, carrots, chard, endive, peas, green onions, parsnips, lettuce, snap beans, bok choy, broccoli, brussel sprouts, cabbage, cauliflower, collard greens, cucumbers, kale, leeks, mustard, radishes, spinach, and turnips.

Don’t Make These Garden Mistakes in September

• When fertilizing citrus, don’t sprinkle the fertilizer next to the trunk — the roots won’t get the benefit there. Fertilize the outer 2/3 of the root area.
• Hold off on transplants of broccoli, brussel sprouts, cabbage, cauliflower, celery, chard, and lettuce until after the end of September or beginning of October. Temperatures must be consistently below 100°F.
• Don’t over-water after transplanting trees and shrubs. Too much water can drown and rot the roots.