What to Plant in July in Zone 10

No frost ever knocks pests back here

Zone 10's defining July problem is not just heat, it is that this climate goes essentially frost free, which means pest populations that a hard freeze would reset in a colder garden simply keep building generation after generation. Aphids can cycle through a full generation in as little as 7 to 10 days in July's heat, and spider mites move nearly as fast once temperatures hold in the 85 to 95 degree range. Whiteflies take longer to complete a generation, typically 18 to 28 days from egg to adult, but with no frost to ever reset any of the three, a small infestation ignored for even 2 weeks can still turn serious by the time it's noticed.

Weekly scouting matters more here than almost any other single practice; check the undersides of leaves on anything still producing, and treat even a light infestation right away with a strong water spray or insecticidal soap rather than waiting to see if it spreads, since waiting in a frost free climate rarely results in the problem going away on its own.

Using the heat instead of fighting it

July's relentless heat is worth putting to work on an empty bed rather than just enduring it: clear plastic stretched over moist soil and left for 4 to 6 weeks pushes soil temperatures into the 108 to 140 degree range at a shallow depth. South Florida's sandy beds drain and dry out faster than heavier soil elsewhere, so soak the ground thoroughly right before sealing down the plastic and check partway through, since solarization only works while the soil underneath stays damp. Done right it knocks back nematodes, a much bigger problem in sandy ground than in clay, along with weed seed that would otherwise carry straight through with no winter cold to slow it down.

A cover crop pulls extra weight in this zone's sandy ground: cowpea or sunn hemp sown across a bare bed germinates readily in July's heat and builds organic matter that thin, fast-draining sand badly needs, on top of fixing nitrogen at the roots. Cut and turn it under 6 to 8 weeks later, right as fall planting gets underway in August.

Cabbage, broccoli, cauliflower, and Brussels sprouts headed for August's open ground need to start now too, 4 to 6 weeks ahead, under 40 percent shade cloth or indoors rather than direct-seeded outside. South Florida's afternoon humidity, on top of soil readings well over 100 degrees at midday, makes direct germination close to impossible this month, so a protected start is the only realistic path to a fall crop.

Water efficiency is the whole ballgame

Deep, infrequent watering beats frequent shallow watering by a wide margin this month; soaking a bed to a full 8 inches of depth once or twice a week encourages roots to grow deep where soil stays cooler and more moist, while a daily light sprinkle keeps roots shallow and vulnerable right where surface soil temperatures run hottest.