Califonia Bountiful

Gardening: Hot stuff

July/Aug. 2010 California Country magazine

Protect your plants from summer's sizzle

Gardeners in California's inland valleys and foothills wait nervously every year as July and August approach. They know the mellow weather of May will change to midsummer's oven-like heat and unrelenting sunshine. And so we dutifully watch weather reports and dread those cruel days when the mercury hits 100 degrees or more. We celebrate days when temperatures are a mere 90 or 95 degrees because we know our gardens will be all right.

So unless you're lucky enough to live in a gentler climate, you'll need to protect plants from Mother Nature's oppressive heat and intense sun.

A few simple fixes help plants survive—even thrive—during those seemingly endless spells of triple-digit temperatures when you think it will never be cool again. Even those who garden where summers are kinder can benefit from these tips because they also save money and time.

  • Top of the list is mulch. A 3- or 4-inch layer of mulch insulates the soil from heat, holds moisture, keeps the soil soft and improves soil structure. Chipped bark, straw and leaves are good choices.
  • Water in the morning. There's less evaporation and plants will be going into the hottest part of the day well-hydrated.
  • Protect newly planted vegetable seedlings and starter plants during the hottest part of the day until they get established. Lay a piece of newspaper, row cover or shade cloth loosely over the plant. I put a lightweight tomato cage topped with a black nursery flat over new vegetable seedlings. Remember to water newly planted vegetables, shrubs, perennials and trees more often at first so they get established.
  • Leave grass clippings on the lawn. The clippings don't make thatch. In fact, they add nutrients to the lawn.

And remember, fall will be here before we know it!

Gardening to-do list for July/August

  • It's time to divide irises. Cut the foliage back to about 4 inches, dig up the rhizomes, replant what you need and plant the others someplace else or give them to friends. You can write the color of the flowers or the name of the iris on the leaves. It makes a great gift for gardening friends. Plus, irises are so easy to grow, they even make a great gift for nongardeners. Remember to tell inexperienced gardeners that irises don't like to be planted too deeply; the tops of the rhizomes like to be just above ground level.
  • The key to growing raspberries is in knowing which canes produce fruit. Mark the vines that are producing fruit now and, at the end of the season, cut them to the ground. They won't produce again.
  • Snip spent flowers from annuals like marigolds, cosmos and zinnias to encourage new blooms.
  • Cut back Mexican evening primrose for a second flush of bloom later in summer. Cut lavender plants back after flowering for a second bloom.
  • Harvest summer vegetables regularly to keep them producing. There's still time to plant another crop of beans and short-season corn, even in higher elevations.
  • Keep an eye on tomato leaves for hornworms. Watch for chewed leaves and black droppings. Toss any hornworms in the garbage or put them out where the birds can find them. There are many birds that like them, even if we don't.
  • Keep dying foliage pulled off daylily plants.
  • Vegetable seeds to plant in July and August include snap beans, broccoli, cabbage, carrots, cauliflower, chard, cucumbers, leeks and lettuce.
  • Check that sprinklers and drip emitters are working properly—watch for dry or dying areas in lawns and flowerbeds—and fix them before plants die from lack of water.
  • If you have clusters of tomatoes exposed to the sun, cover them with shade cloth, row cover or even newspaper to protect them from scalding.

Pat Rubin is a longtime gardener and ­garden writer. Send questions or comments to her at

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