Garden Plot: Heat wave? That’s a tidal wave a’comin’

Once again, the 10-day forecast predicts a heat wave, but this one looks to be all day every day with little chance of any substantial rain.

First Up: Protect Baby Plants

I know that driving rains are not far back in our memories, but newly installed plants like tomatoes, peppers, eggplant and bedding flowers are still small, with little capacity to hold a lot of water, and great vulnerability to sunscald when temps top 90 this early in the game.

Here are new rules for watering at this time of year in this Hot New World:

  • Only water in the early morning; that’s when even small plants can store the greatest amount of water.
  • Water applied in the middle of the day is a complete waste.
  • Nighttime watering invites disease, especially in humid weather.
  • Despite this intense heat, do not water every day. Ideally, water every third day for an hour or more at a pop.
  • Short waterings (under half an hour) are worthless.

Pay Extra Attention to New Trees and Shrubs

If you have newly installed trees or shrubs, now’s the time not to kill them. Their root systems have not yet fully engaged with your soil, so they can’t hold the same amount of water as established plants.

To prevent their early demise, let a hose drip slowly at the base of each newbie for several hours, preferably in the morning, Second choice: similar drip irrigation in the evening; never water in the heat of the day.

Repeat this watering at the base every third day. Move the hose around from plant to plant if you put in a lot of new ones. Established plants don’t require such dramatic help, but new ones do—even if they were planted last fall; they still count as new.

Cool Weather Crops Are Out of Luck

If this were a normal spring (summer doesn’t officially arrive for another month) it would be the ideal time to be growing cool weather crops—like spinach, salad greens, broccoli and the like. But the weather the next ten days will be better for choppin’ broccoli than growing it.

Our plants of summer, like tomatoes, peppers, eggplant, zucchini, melons and squash, love warm weather; lettuce and spinach do not.

To try and keep them from bolting and turning bitter, water them every morning—yes, EVERY morning—and try to rig up some afternoon shade, like with a beach umbrella or moving plants in containers out of the sun after lunch. Even with extra watering, cool-season plants in full sun all day will turn bitter and go to seed.

If that happens, let them flower!

Don’t try and eat the leaves anymore, but do leave the plants in the ground. They’ll grow a tall, central stalk that will produce tiny flowers that attract pollinators and beneficial insects. After the flowers fade, seed heads will form; when those seed pods are bone dry, harvest them and sow the seeds for a fall crop of good eating.

Violets: Eat Your Weedies!

“Ms. Simpson” in Riverdale Park writes:

“I’ve been told that wild violets are rather hard to control. Shame! They’re all over my garden bed! Besides pulling everything else out with them–rose bushes, daylilies, etc.), what else can one do?”

Eat ‘em, Ms. Simpson! (Or should I call you ‘Marge’?)

All members of the Viola family—which includes pansies, violas, Johnny Jump Ups and wild violets—are not only edible, but they’re the only edible food source of rutin; an essential nutrient that helps regulate blood pressure.

More importantly, rutin can prevent or reverse the visible effects of spider and varicose veins—and the pretty flowers that provide this benefit begin to appear several months before swimsuit season; such a deal!

Save Your Local Lightning Bugs!

Linda on the Eastern Shore of Maryland writes:

“Will herbicides mess up the natural habitat of fireflies, worms and other important organisms? We live on about four acres, 1 1/2 of which are located in a brackish water pond behind our house. We have nice landscape beds and trees that need mulching every year or two. This is the first year we are paying someone to do it. They wanted to use ‘Preen’ and I immediately said no. I would like to know if it is harmful and what alternative I can use.”

Preen is a company name and not a specific product, but most of what they sell are chemical herbicides that do harm aquatic creatures like frogs and toads and insects that breed in damp areas, like fireflies. Alternatives depend on the problem and the location, but chemicals are never the answer.

Oh—and established trees need no mulching. If you must mulch for weed control, begin the mulch six inches away from the trunk and carry it all the way out to the dripline (roughly as far as the furthest branch reaches above).

Never apply any mulch deeper than 2 inches and NEVER let the mulch touch the trunk of the tree. If your landscaper wants to ‘volcano mulch’, get another landscaper.

And PLEASE—don’t use (or let someone else apply) that awful dyed mulch!

  1. That dye could be covering up the fact that your ‘triple premium shredded mulch’ is actually construction debris, pressure treated wood and/or chipped-up insecticide-soaked pallets from China.
  2. Did your parents raise you to have a front yard the color of a Burger King??!!

Mike McGrath was editor-in-chief of ORGANIC GARDENING magazine from 1990 through 1997. He has been the host of the nationally syndicated public radio show “You Bet Your Garden” since 1998 and WTOP Garden Editor since 1999. Send him your garden or pest control questions at

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