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Hot Season Crops

Top-down view of a variety of squash and pumpkins of many diameters and colors
Karolina Grabowska via Pexels

Much as I love life here in Southern Nevada, our springtime is remarkably short. You scarcely have time to get your vegetable seeds into the ground before temperatures pop up into the nineties. I often talk about “cool season” and “warm season” plants, but we don’t spend enough time thinking about hot season crops.

Granted, there’s not a lot of them, but there are some vegetables that can survive, perhaps even thrive, into the low 100’s.

I should start off by saying what definitely won’t flourish in hot weather — think about green leafies, like spinach, broccoli raab or lettuce. You might be able to keep them growing into June, but July is usually out of the question. Same goes for root vegetables. Carrots, beets, turnips — they won’t thank you for pushing them into the hot weather.

Many of our favorites are fine in a warm season but usually suffer when it’s hot outside. Tomatoes, for instance. Everybody wants a tomato that’s succulent and delicious — something we rarely find in a grocery store. Tomatoes grow wonderfully well until about mid-June, but to keep them growing later than that requires providing them with 30% shade and ample water. They really don’t like temperatures much above 85°.

Some of their close relatives can usually grow into the low 90’s. Peppers and eggplant aren’t thrilled with really high heat, but they do better than tomatoes.

So, what will enjoy growing during a Mojave Desert summer?

More than you might imagine.

Fennel’s a surprise. Four years ago, I bought a package of seeds for “annual fennel.” I was looking forward to the tasty fern-like leaves for tea, and I got the leaves, as well as the bulbs, and the seeds. It’s technically a “tender perennial,” but I don’t know how tender.

By this past march, I had a bumper crop of leaves. I’ll probably get bulbs and seeds by early summer.

Think about sweet potatoes, which are not yams, by the way, but that’s another story. Sweet potatoes thrive in our challenging climate. I plant them the end of May and by Thanksgiving I have sweet potatoes for the "feast." At the Extension demonstration community garden, Master Gardener volunteers have grown hundreds of pounds of sweet potatoes.

Just make sure the soil is fertile, and loose enough so the roots can expand. It’s another time when adding compost makes all the difference.

Members of the melon family, which includes winter squash and pumpkins in addition to cantaloupes and watermelon, they thrive in the heat. The roots of melons like cantaloupe won’t even "pull up" water if the soil temperature is less than 60°.

If the soil is fertile and well drained, they’ll produce fruit through the summer.

Winter squash and pumpkin plants will grow in the summer, but don’t produce much fruit until fall. In fact, at some school gardens, the children plant pumpkins around May, and as long as the plants are kept watered though summer, they’ll usually have pumpkins in time for Halloween!

The biggest problem with melons and squash is an insect called “squash bug.” I hate this creature. Their mouths pierce leaves and suck out the sap. Damage shows up as brown spots on leaves, followed by wilting. Young plants can even die. The best control is to pay close attention, and pick them off using duct tape as soon as you see any, otherwise you’ll have millions. And they overwinter, especially if there’s leftover plant material where they can hide. Adults are brownish grey, and just over a half inch long. If you can get them before they reach adulthood, they won’t lay a new generation.

I don’t recommend insecticides, but washing the plants gently with soapy water can help keep the population down.

You’ll get a crop of delicious fruits.

So, hot weather in the Mojave doesn’t mean that your garden’s dead. Just choose plants that have a chance of surviving here.

For KNPR’s Desert Bloom, this is Dr. Angela O’Callaghan, Emerita Professor of the University of Nevada Extension. Enjoy your summer!