15 Summer Annual Tips

Keep your annuals looking their best all summer long by following these easy-grows-it tips.

Photo By: Photo courtesy of Proven Winners

Photo By: Photo courtesy of Ball Horticultural Company

Photo By: Photo courtesy of Altman Specialty Plants

Photo By: Photo courtesy of Proven Winners

Photo By: Photo by Julie Martens Forney

Photo By: Photo courtesy of Ball Horticultural Company

Photo By: Photo courtesy of Proven Winners

Photo By: Photo by Julie Martens Forney

Photo By: Photo courtesy of National Garden Bureau

Photo By: Photo courtesy of Proven Winners

Photo By: Photo by Julie Martens Forney


Photo By: Photo courtesy of National Garden Bureau

Photo By: Photo courtesy of National Garden Bureau

Photo By: Photo by Julie Martens Forney

Photo By: Photo courtesy of Proven Winners

Annual Showtime

Brightly colored annuals bring summer to life. With a little TLC, these head-turning plants can hold their own all the way to fall frost. Follow our simple tips to coax long lasting, eye-catching performance from these plant powerhouses.

Water Containers

Once annuals hit their stride and fill out containers, your job is supplying enough water to fuel growth. For containers with drainage holes, slip a saucer beneath pots to catch overflow from watering or rain. By midsummer, most pots need a daily dousing. If you have a particularly large plant, like pineapple sage or hibiscus, in a pot, you may need to water twice a day, especially when temperatures rise.

Reduce Plant Height

When growing tropicals or perennials in pots, bring them into flower at a shorter height by trimming stems in early to midsummer. Reduce stem height by up to half. This causes plants to flower a little later, but it saves you the difficult chore of trying to stake tall plants in pots. Good candidates include traditional tall varieties of Mexican bush sage (shown), joe pye weed, asters and butterfly bush.

Feed and Trim Supertunias

By July 4, Supertunias in containers should be sprawling and crawling over pot edges. Feed your plant’s appetite by fertilizing every other watering. Trim roughly one in five stems, cutting them back even with the bottom of the container. Give the rest of stems a light trim, cutting them back a few inches. Repeat the trim treatment in late summer if plants look straggly.

Trim Petunias

If other petunias look like this—flowers only at the end of stems and stems peppered with seedpods—it’s time for a trim. Cut stems back to near the container edge to promote new growth. Remove any remaining seedpods on trimmed stems. After trimming, water and fertilize plants by tossing some slow-release fertilizer onto soil.

Harvest Flowers

Cut flowers for drying all summer long. Good bloomers for easy air drying include gomphrena, strawflower, tall ageratum and wheat celosia. Harvest stems often throughout the summer whenever blooms are ready. Frequent cutting means plants produce more flowers—and you have more dried blooms to craft and share.

Remove Flower Buds

Foliage favorites, like coleus, caladium and polka-dot plant, are prized for their colorful leaves. Keep the leaves going strong by removing flower buds as soon as you see them. To keep this chore off your to-do list, look for newer coleus varieties that flower very late in the growing season, if at all.

Feed Plants

Tend to tall annuals like hollyhock, love-lies-bleeding, cosmos and old-fashioned cleome. These taller plants can easily fall over or break in summer thunderstorms. Eliminate that chance by staking plants in early summer. Use half-hoops to support a clump of plants, or individual stakes for single stems.

Watch for Mildew

Zinnias bring glorious color to summer gardens and bouquets, but leaves are prone to powdery mildew. The time to treat for this disease is before you see it. Once powdery mildew starts, it’s really too late to eliminate it, but you might achieve some control if you start spraying plants. Look online for solutions, including traditional fungicides, neem oil, or baking soda sprays. In future, avoid planting zinnias too closely, and look for disease-resistant varieties.

Trim Cool-Season Annuals

Breathe new life into cool-season bloomers like sweet alyssum and snapdraon by trimming plants back by half, fertilizing and keeping them watered through summer heat. You might be rewarded with a second flower show as fall’s cooler air arrives.

Stake Tall Plants

Tend to tall annuals like hollyhock, love-lies-bleeding, cosmos and old-fashioned cleome. These taller plants can easily fall over or break in summer thunderstorms. Eliminate that chance by staking plants in early summer. Use half-hoops to support a clump of plants, or individual stakes for single stems.

Protect Brittle Stems

Some annuals, including Salvia coccinea, begonias, shorter cleomes, Salvia farinacea and ivy geraniums, benefit from a protected growing location, especially in windy areas. These plants have more brittle stems that break easily. As plants get larger and lean out of pots, brushing by plants can accidentally remove entire branches. Try staking plants with half hoop stakes or sections of wire garden fence.

Remove Spent Blooms

Depending on how many annuals you have, tackle deadheading once or twice a week. Clip or break stems as close to the base as possible. Toss them onto a compost pile or into a yard waste bin. If you let them lie in place, they may develop mold (Botrytis) as they decompose, which can spread to healthy blooms. Geraniums are especially susceptible to Botrytis.

Watch for Botrytis

As summer rains pour, botrytis (mold) can quickly develop on plants, especially those in crowded conditions like tightly packed container gardens. Certain annuals are more susceptible to botrytis than others, including rudbeckias, geranium, zinnia and begonias. Mold frequently forms on dying flowers, then quickly spreads to leaves. It can wipe out an entire pot if rainy weather persists. Remove spent blooms to help control this disease.

Water Million Bells

Allow soil in pots with million bells to dry out between waterings. If plants are straggly looking, give them a light trim, removing a few inches of tip growth. If leaves are yellow and you added slow release fertilizer at planting time, start feeding plants. Either add more slow release fertilizer to containers, or use a liquid fertilizer when you water, applying it roughly once every 7 to 10 days.