August Gardening Tips for the Mountain West and High Plains

Summer heat ripens the harvest and coaxes late-season perennials into glorious flower.

Harvest Time

Check your vegetable patch daily to stay on top of ripening produce. When fruits like beans, tomatoes, and squash become overripe, their presence on the plant discourages younger fruits from maturing.

To get the tastiest produce, follow these guidelines for harvest:

Carrots: Pull when roots are quarter size or smaller.

Corn: Pick when silk browns and kernels run milky when pierced with a fingernail. Watery juice signals immature kernels; a pasty texture indicates corn is overly ripe.

Green beans: Tender beans are about as thick as a pencil. French filet beans will be smaller.

Peppers: Peppers grow hotter or sweeter the longer they remain on a plant. Harvest at the flavor stage you prefer.

Potatoes: When tops turn brown and fall over, it's time to dig.

Squash: Harvest smaller squash for the most tender flavor. Pick blooms to batter and fry.

Tomatoes: Fruits that ripen on the vine pack the sweetest flavor. Cherry tomatoes tend to crack; pick as soon as they show color.

Test Garden Tip: Plant cool-season vegetables now for fall harvests. Good choices include beet, lettuce, spinach, radish, scallions, and bok choy. Choose varieties that mature in 50 days or less. Sow near taller, established plants to give seedlings some shade.

Late-Summer Irrigation

Watering can easily consume your gardening hours. Make the most of irrigation efforts by following these tips:

  • Avoid watering between 10 a.m. and 6 p.m. During these peak heating hours, more water evaporates than soaks into soil.
  • Check sprinkler systems. As plants grow wider and taller, foliage can block spray heads or limit water dispersion. Trim offending plants or add a temporary extension to the sprinkler system.
  • Refresh mulch. Some mulch materials, like straw or grass clippings, break down quickly. Continue to replenish mulch through summer to cool soil and slow water evaporation.
  • Use a moisture monitor to check soil weekly during prolonged dry periods. If soil is dry several inches deep, it's time to irrigate. Check soil moisture in lawn and planting beds. You can get a monitor at garden centers or home improvement stores.
  • Feed as you irrigate. Frequent watering washes fertilizer from containers. Consider mixing liquid fertilizer to half strength and applying at each watering to keep plants in top form.
  • Check hanging baskets twice daily for dry soil. Because baskets are suspended in midair, their soil temperature is typically warmer than that of pots sitting on the ground. Warmer soil loses water more quickly.


Harvesting: Herbs continue to form new leaves as long as you keep picking older ones. The best time to harvest is before any flowers form. When herbs bloom, leaf flavor changes. Pick leaves in the morning after dew dries. Exceptions are varieties of mint, which have a greater concentration of essential oils at high noon.

Drying: You can dry herbs using several techniques; either scatter leaves on old screens or in baskets, or gather stems into bundles with string or rubber bands and hang bundles upside down in a cool, dark, dry place. After leaves dry, store them in airtight containers in a dark place -- such as inside a cupboard. Flavor stays stronger, longer when leaves remain whole. Chop herbs just before using.

Freezing: You can also freeze herbs; layer chopped leaves into ice cube trays, cover with water, and freeze. Or process herbs with olive oil using a blender or food processor. You'll wind up with a slurry of finely chopped herbs. Freeze the mixture in ice cube trays. Once cubes are frozen solid, dump them into zipper-style freezer bags. When cooking, use a cube to season winter soups and stews.

Easy-to-grow herbs.

Clever containers for indoor herbs.

August Garden Chores

Compost: Cook some compost. Hot summer weather will break down compost fast. Begin building a new pile now, and it could be ready by fall. Also, don't place currently cooking compost around plantings. It's probably still too hot. Set it aside and allow it to continue composting. Or, use it as an amendment for new planting areas, digging it into soil and allowing it to compost until spring.

Divide irises: Dig and divide irises until midmonth. Dig up rhizomes with a spading fork, and cut or snap each leaf fan so it's free of the main clump and has a 3- to 4-inch-long rhizome attached. Cut leaves to 6 inches. Place the rhizomes in a circle in a shallow basin in soil, with leaves facing out. Bury rhizomes with a shallow soil layer.

Lawns: Raise mower height. You should be letting grass grow taller now to shade roots and cool soil. Aim for a 3-inch height for most Mountain West grasses, including Kentucky bluegrass and tall fescue.

Houseplants: Any indoor plants spending the summer outside need fertilizer during these peak growing weeks. Using liquid fertilizers, give flowering plants a bloom booster product every 10-14 days. Fertilize leafy plants every two weeks with a 20-20-20 liquid fertilizer mixed to full strength.

Learn how to make compost.

Lawn-care guide for the Mountain West and High Plains.


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