by CAROL O’MEARA Colorado State University Extension

This summer is shaping up to be a season of abrupt extremes. After starting off with snow in early May, we tipped the other way into broiling heat. That wasn’t good enough for Mother nature, so she spun the weather back to cool – near chilly – weather to end June. On any given day, I have no idea what I’m supposed to grump about.

But the bottom line is summer heated up in a hurry, and yards, vegetables and trees are showing the price of the record heat in between the rains. This kind of summer takes its toll on many plants, especially once the soil begins to dry. Trees with lush canopies from all the May moisture have dense foliage; too much to support if the heat returns because the soil won’t have as much moisture for all the leaves.

To deal with this, trees will thin canopies by dropping leaves they can’t support under hot, dry conditions. This is normal and particularly common in ash and cottonwood. Like most slimming regimens this doesn’t harm the tree, it simply helps it live within its means.

Shade cloth over vegetables prone to sunscald is a great way to prevent that problem. Peppers, tomatoes, lettuce and any other crop, such as the cabbage, will benefit from a bit of shade. In studies conducted at Colorado State University, University of Maryland and Georgia State, a 30-percent shade barrier is ideal for protecting these plants.

Shade cloth is a loosely woven material that can be placed over crops in a tent. It allows plenty of sun to filter through but takes the edge off its harsh rays. You can cut and sew it to size to fit whatever support you choose; I use a PVC pipe frame but others have hoops. Find shade cloth at the local garden centers, but because not all retailers carry it, call ahead to see if they have it.

One of the most obvious areas to suffer from heat is our lawns. Brown spots bloom everywhere, and sprinkler sections at local hardware stores sizzle with action.

Most brown areas are due to poor watering of the lawn. Check the coverage of water on your lawn by conducting a catch-can test to check the amount of irrigation you’re putting down. Gather six to eight cans of the same size and randomly place them around the area you’re having problems in, making sure to place some in the green and in the brown areas. Run your irrigation like normal. Measure the amount you’ve put down to see how much the lawn is getting each time. In general, bluegrass needs two inches of water per week, spread out over two to three waterings.

Don’t forget to adjust the run times on automatic sprinkler systems to deliver more water to lawns, flowers, vegetables and trees. Perennials and annuals that put on good growth since spring need to have water increased to accommodate their larger size. Trees planted years ago with drip irrigation should have the lines and emitters checked to make certain they’re delivering enough water for older trees.

Most herbaceous plants will look droopy in mid afternoon – much like gardeners do – but those with enough water will spring back once evening arrives. Plants that don’t rebound in the evening should be given a drink, and if this doesn’t help, check their stems for signs of disease.

With any change in irrigation, be alert to signs of trouble. Lawns don’t need water every day, and if you are running your sprinklers that often you may need professional help.

By Carol O’Meara. Carol is an Extension Agent – Horticulture Entomology at Colorado State University Extension Boulder County. For more information call 303.678.6377, e-mail [email protected] or visit