Gardening experts provide tips for late summer splendor

The dog days of summer have arrived, and even the most avid gardeners can struggle to keep their gardens bright and productive during the long, hot days of August. 

Fortunately, the eighth month of the year is the perfect time to complete maintenance, propagation and upkeep in the garden, and many expert growers have started sharing tips for late summer garden splendor. 

Cut back, harvest and collect 

At the end of the season, many perennials may start to look ugly and overgrown and flowers begin to wilt and dry out. Therefore, it is a good time for growers to lightly trim dead or dying branches, stalks and foliage and deadhead spent flowers. 

However, it is advised to use a light touch when pruning perennials late in the season since pruning encourages new growth, which hasn’t had a chance to harden off and is more easily damaged by frost, making the plant more vulnerable to destructive cold damage. 

Although many annual and perennial plants are bred so deadheading isn’t necessary, self-seeding varieties benefit from removing dead flowers so they can spend more energy on growing flowers and less on producing seeds. 

Experts recommend using sharp, clean shears to snip off spent flower heads weekly, which should encourage a light, late rebloom in many plants. 

This is also a perfect time for those who wish to collect seeds to use the following year.

Seeds should be separated from the chaff and stored in small, lidded and labeled containers or paper envelopes in a cool, dark and dry location. 

Like beautiful flower blooms, reaping healthy, tasty crops is a highlight for many gardeners, and late summer is when harvest is in full swing. 

Growers should keep an eye out for mature crops and harvest small amounts frequently. 

In the University of Wyoming’s (UW) “Gardening Vegetables in Wyoming Guide,” UW Extension Horticulture Specialist Karen Panter states, “Harvesting should be done frequently and at the proper stage of vegetable maturity. It is often the most rewarding part of vegetable gardening, but a common mistake is allowing produce to become overmature, losing the best flavor or appetizing texture.”  

Fertilize, mulch and water

In many areas, late summer is the hottest and driest time of year. Therefore, growers should hold off on fertilizing plants as roots and foliage of heat-stressed, weakened plants are more susceptible to burn from fertilizer salts. 

“Instead, continue to water heat-stricken plants and trim them back by one-quarter if needed,” suggests Author, Artist and Gardener Lorna Kring in a Gardener’s Path article published on July 14, 2023. “Then wait until temperatures cool off late in the season before a final feeding.” 

She adds, “Or, growers can fertilize lightly with a one-quarter strength solution of liquid or water soluble fertilizer, just avoid full-strength applications.” 

Kring notes mulching is also good practice during hot months, as mulch reduces plant stress by keeping soil temperatures down, roots cool and retains moisture by slowing down evaporation. 

Examples of mulch materials include straw, grass clippings, kelp, leaf mold, pine needles, untreated sawdust and pine boughs, to name a few. 

“Spread a two- to four-inch layer of mulch evenly over the root zone and out of the dripline, keeping materials a couple of inches away from the crowns and stems of any plants susceptible to issues like crown rot or root rot,” Kring says. 

“If desired, individuals can leave their mulch in place over winter to protect roots from cold damage, provided there are no obvious pest or disease problems. Or, if no pests are present, natural mulches can be dug into the soil in fall,” she adds. “Should plants have insect or pathogen problems, remove the mulch in autumn and dispose of it in the garbage or by burning it. Do not add it to compost.”

Additionally, Kring notes nothing is more important for a late summer garden than proper watering, as many annuals and perennials need an average of one inch of water per week. 

“Lawns and turf need to be watered frequently in hot weather to prevent the onset of dormancy, and trees and shrubs typically need about two inches of water per week in dry spells,” she points out. “Water slowly and deeply to ensure the entire root ball receives moisture, which helps roots grow deep.”

“Also, avoid watering the foliage to inhibit the spread of pathogens. A drip or soaker irrigation system on a timer is an easy and economical way to complete weekly watering tasks,” she adds.

Weeds and pests

Although weeds are a nuisance for gardeners all summer long, they particularly thrive in the hot temperatures of late summer months and will steal nutrients, sunlight and water from other plants. 

Growers should weed frequently in order to catch them while they are young and small and before they seed. 

It is also important to keep an eye out for signs of hot weather pests like aphids, cutworms and spider mites and diseases such as blight, powdery mildew and rust. 

Experts recommend manually removing insects by spraying plants with water, being sure not to miss the undersides of leaves, and treating gardens with natural pesticides like neem oil and organic insecticidal soap. 

Make the most of the growing season

In order to make the most of the growing season and keep gardens looking bright late in the summer, growers may consider replacing early-flowering annuals like pansies, snapdragons and tulips with heat-loving plants such as angelonia, zinnia or sweet potato vine. 

Additionally, individuals looking for a pop of color late in the season can set out summer-flowering bulbs like calla lilies, canna lilies, dahlias and gladiolus. 

“Most of these plants are cold tender, so they’re typically planted in beds and borders in mid to late spring after all danger of frost has passed or they can be potted up early in temporary containers to start growing in a protected site, then planted out when spring-flowering bulbs like daffodils and tulips have finished and died back,” Kring explains.

August is also a great time to plant late-season, cool weather crops such as broccoli, beets, cabbage, carrots, leeks, radishes, scallions, arugula, collards, kale, lettuce, mustard, spinach and Swiss chard, just to name a few. 

These plants are usually harvested in the fall or overwintered and picked early the following spring.

Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments to roundup@wylr.net.