What to do in your Mountain garden in August


This is the best time of year to divide established peonies or to plant new ones. Plant peony tubers with the growth buds (called “eyes”) no more than 2 inches deep in soil amended with plenty of organic matter.

Try Belgian chrysanthemums, also called cushion mums. Jake Wolf of Nick’s Garden Center in Aurora, Colorado, is a fan of this new generation of mums, which form compact mounds. They don’t require pinching, return year after year, and have strong stems that don’t break under early snow loads. Wolf’s favorites are July-blooming pink ‘Ozenda’, August-blooming yellow ‘Unoco’, and September-blooming red bronze ‘Sorella’.

Pull out faded spring and summer flowers and replace them with annuals that will look good well into autumn. All of the following can withstand frost down to temperatures in the mid-20s: African daisy, begonias, Euphorbia ‘Diamond Frost’, gazania, geranium, gerbera daisy, Helichrysum ‘Icicles’ and the Licorice series, lantana, nierembergia, petunia, salvia, silver dichondra, Sutera ‘Gold ‘n Pearls’, Swiss chard, and verbena. If hard frost (below 20º) is predicted, cover plants with an old sheet or frost blanket.

Plant cool-season vegetables like ‘Detroit Dark Red’ and ‘Ruby Queen’ beets; bok choy; ‘Chantenay’ and ‘Nantes Coreless’ carrots; ‘Winter Stout’ Chinese cabbage; cilantro; ‘Black-seeded Simpson’ loose-leaf lettuce; ‘Winter Density’ romaine lettuce; ‘Black Spanish’, ‘Cherry Belle’, and ‘White Icicle’ radishes; and scallions. Look for days-to-harvest information on seed packets and choose varieties that mature in 50 days or less.

Move over, orange! This year, plant carrots in hues of purple, cream, and yellow. In Sunset‘s Test Garden, we grew ‘Yellowstone’, ‘Purple Haze’, and ‘White Satin’ and loved the color and taste of all three. Prep a sunny bed by removing stones and clods 1 foot deep to ensure smooth, straight carrots; sow seeds directly, and keep soil evenly moist. When seedlings are a few inches tall, thin to 1½ inches apart. The above varieties reach maturity in 65 to 75 days; check for size before then by pulling a few, and enjoy them as finger-size baby carrots. Seeds are available from Johnny’s Selected Seeds.


Control budworms. Chewed buds or flowers on geraniums, penstemons, or petunias are usually the work of geranium (tobacco) budworms ― small greenish-tan or reddish-striped caterpillars. Handpick them early in the morning or spray Bacillus thuringiensis (Bt) to kill them. Pick off dried-up buds and flowers, spots where budworms may hide. Ivy geranium is seldom bothered by these pests.

Watch for aster yellows. Stunted, twisted growth and oddly distorted flowers are the symptoms of aster yellows, a disease that often shows up in midsummer. Sucking insects, primarily leafhoppers, transmit this disease that infects asters and many other plants. Affected flowers should be pulled up and discarded immediately to stop the spread of the disease; control weeds such as dandelions, plantains, and thistles, which may carry it. Cover vegetables with floating row covers to exclude leafhoppers. For severe infestations of them, use neem oil.


For the strongest flavor, harvest leafy herbs like basil, chives, oregano, parsley, sage, tarragon, and thyme before they flower. Cut bunches, rinse with cold water, and dry them off. Use the leaves fresh, or bunch stems together with a rubber band and hang in a cool, dry place. Harvest seedheads of coriander, dill, and fennel as they start to turn brown, and dry in a paper bag. Then put dried seeds in the freezer for 24 hours to kill any hitch-hiking insects. Store dried leaves and seeds in airtight containers.

Check for mature veggies every morning. Pluck beans when the pods swell. Dig carrots when the tops are 1 inch across. Clip outer leaves of collards, kale, spinach, and Swiss chard so plants will continue producing. Harvest corn when the silk is brown and kernels are plump and sweet. Pick cucumbers and summer squash while still on the small side, and tomatoes and peppers as they become fully colored. Dig up garlic, onions, and shallots after their tops fall over and start to turn brown. Pick fruit Harvest apples, apricots, cherries, currants, grapes, peaches, plums, and raspberries when they look, smell, and taste ripe ― fruit that’s ready comes off with a slight twist. Pick pears while they are still green and ripen indoors in a cool, dark place. Use care when harvesting tree fruits so you don’t damage the twigs, called spurs, which produce next year’s crop.