15 Late Summer Garden Tips for a Successful Harvest

The late summer season brings an array of rewarding gardening tasks that offer both beauty and bounty. Borders are filled with beautiful late summer flowers, and there's plenty of vegetables to harvest in the garden beds. August and September are the best times for maintenance, division, propagation, lawn care, mulch, and upkeep. It's time to enjoy the harvest from your garden and make gains for next season. In late summer, days start getting shorter, but you can still take steps to extend the summer season and keep your garden flourishing until fall arrives and winter sets in. There are summer crops to harvest, seeds to collect, plants to monitor, perennials to divide, and the need to apply water consistently as the growing season moves on.

Here are 15 tips for a late summer garden that will keep your garden going strong to get a successful harvest or get started before the snow falls.

1. Collect Seeds

By August, many plants will have finished flowering and set seed, which ripens in the warmth of the summer sun. Annuals such as poppies and nigella will now be setting seeds now. When mature seed heads change from green to brown, beige, or gray, collect the seeds by removing the seed heads from the stalk.

Collect seeds in lidded containers or paper envelopes for next spring's sowing and remember to label the envelopes. Store them in a cool, dry, and dark place, such as a drawer or cupboard, until next year's planting time.

2. Harvest Ripe Summer Crops

Late summer means we're in peak season for early summer-planted fruits and veggies. Check your garden daily for new gifts ready to be savored and turned into delicious meals. Harvest vegetables when they are ripe and avoid over-ripening. Harvest apples, blackberries, plums, pears, and raspberries.

Continue harvesting, freezing, and canning till fall to get the full benefits of your hard work. The more you harvest, the more your plants will be encouraged to produce new growth. Use clean, sharp cutting tools to properly cut vegetables from the plant. This will reduce damage to the harvest and minimize the risk of disease.

3. Mulch for Cooling

Mulching in late summer is a simple yet effective way to cool down the roots, regulate soil temperature, retain moisture, suppress weeds, and reduce stress on plants. A summer mulch will enhance the health and productivity of your garden.

Many types of organic materials, such as grass clippings, straw, pine needles, leaf mold, kelp, and untreated sawdust, make excellent mulch. When these materials decompose, they release beneficial micronutrients into the soil and improve soil health.

4. Time to Fertilize

If your area has hot and dry weather in late summer, you may want to avoid fertilizing your plants. Fertilizing plants that are already stressed from excessive heat or dry conditions won't help them recover and may cause more harm than good. This can make the roots and leaves of weak plants susceptible to burning from fertilizer salts.

Continue to water heat-stressed plants consistently and give them a little trimming, if necessary, then wait until late in the season for a final feeding. Instead, you can fertilize lightly with a solution of liquid or water-soluble fertilizers, but avoid full-power applications.

5. Start Planting Cool-season Crops

Late summer is the perfect time to plant those late-season, cool-weather crops in your garden, which can be harvested in the fall or overwintered and picked in early spring. Sow seeds of spinach, lettuce, and other fast-growing leafy greens for fall salads. Some veggies like kale and Brussels sprouts benefit from a light frost, but many greens will turn black from frost. The best way to protect crops from frost and extend the fall season is to install floating row covers over the garden rows or beds. They will protect tender plants from cold temperatures.

Cool Season Crops: Beets, broccoli, Brussels sprouts, carrots, kohlrabi, radishes, cabbage, cauliflower, leeks, and scallions. It also includes many leafy greens such as kale, spinach, arugula, collards, lettuce, mustard, and Swiss chard.

6. Plant Hardy Summer-blooming Bulbs

If you want to fill your garden with gorgeous colors in late season, set out some hardy summer-flowering bulbs like dahlias, gladiolus, crocosmia, calla lilies, and canna lilies. Most summer bulbs are cold-sensitive, and they're planted from mid to late spring after the final frost. However, these hardy bulbs can be set out in September and October. Spring-blooming bulbs, such as daffodils, tulips, crocuses, and hyacinths, are typically planted by the end of September.

7. Tackle the Weeds

The weeds can sneak up on your garden so fast. They rob the beauty of our gardens and quickly steal nutrients and water from the plants you grow. Weeds thrive in hot temperatures and can produce thousands more. Therefore, weeding is the most crucial garden task to do in your September maintenance list.

Keep weed growth in check and remove them with a weeder before they set seed. Walk around your garden in the morning or evening with a basket to pull out weeds as you see them; this will make the task a little more fun.

8. Propagation

Self-seeding is an economical way to propagate various annuals, perennials, biennials, herbs, and flowering bulbs. When seedlings emerge the next spring, you can leave them in place or lift and transplant them to a more desirable location once they reach about six inches in height.

Species and open-pollinated plants are excellent choices for self-seeding because the seeds from many hybrid species do not reproduce true to the parent plants.

Here is a partial list of common self-seeders.

• Annuals: Nasturtiums, cosmos, and snapdragons
• Perennials: Delphiniums, borage, and columbine
• Biennials: Poppies, foxgloves, and sweet williams
• Bulbs: Crocosmia, alliums, and muscari
• Herbs: Sage, parsley, and oregano

9. Spruce Up Containers

Container plants are often the first to exhibit show signs of heat stress as the hot summer season progresses. They can show tired foliage, fewer blooms, and leggy growth. Water your planters regularly and fertilize them to keep them blooming vibrantly through the entire season. Proper watering and fertilizing of potted vegetables, such as tomatoes, cucumbers, and peppers, is essential for a bountiful crop.

Remove dead or damaged leaves and flowers, clean debris from containers, and inspect for and treat pests. Rotate containers a quarter-turn every few days to expose all areas of the plants to sunlight.

10. Deadhead Flowers

Keep up the deadheading roses, dahlias, cosmos, and daylilies for a flush of autumn colors. They will continue to flower for longer if deadheaded regularly, and they make lovely cut flowers. Deadheading allows plants to rebloom, maintain a tidy appearance, and prevents aggressive self-seeding.

Use clean, sharp pruning shears to cut flower heads weekly, which will promote a late rebloom in many flowers. If you want certain plants to self-seed or want to collect seeds, leave a few seed heads to remain and collect them when they ripen.

11. Cut Back and Divide Perennials

Cut away lightly faded perennials. When perennials look ragged or become overgrown late in the season, a little trim can revive their appearance. Remove dead or dying branches, flower stalks, and brown or wilted leaves.

Late summer is also an ideal time to lift and divide perennials such as bearded iris, oriental poppies, foxtail lilies, and astilbe when they're dormant. Division and transplanting will reduce overgrown clumps, providing you with extra plants. However, avoid moving or dividing plants when they are in bloom, as this can cause stress. After dividing and transplanting plants, water the divisions thoroughly to settle them into their new planting locations and then water regularly until they are established.

12. Check Your Irrigation System

Another late summer garden tip to achieve a successful harvest is to inspect your garden's irrigation system, including a drip irrigation system or sprinkler system. Inspect drip tubing, fitting connections, emitters, sprinklers, and all other components to ensure everything is in good condition and working perfectly.

Check for signs of over- or underwatering, such as dry soil, water pooling, plant wilting, or yellowing leaves. Adjust your irrigation timer settings based on the plants' watering needs and changing weather conditions.

13. Do Lawn Maintenance

August and September are ideal times for lawn maintenance. Remove the debris using a rake, aerate the lawn, and feed it with a high-potassium fertilizer to harden the grass for the upcoming cold winter weather.

By midsummer, raise the cutting height of your mower blade to keep your lawn looking healthy and lush. Allow the grass to grow longer to keep the roots cool and reduce evaporation. Mowing is usually stressful, and the lawn recovers faster when cut in cool evenings instead of afternoon heat. Moreover, late summer is a good time to reseed your turf and water it regularly.

14. Watch for Pests and Diseases

Just like weeding is an important step, pest and disease management are also crucial throughout the growing season.  Keep an eye out for hot-weather-loving pests, such as aphids, beetles, caterpillars, cutworms, and spider mites, as well as diseases like powdery mildew, blight, and rust.

How to prevent these problems? Space plants properly for optimal air circulation, water regularly using drip irrigation, and plant them in well-drained soil. Use row covers to protect plants from beetles, caterpillars, and other pests.

15. Water Consistently

Proper watering is one of the crucial factors in creating a beautiful, healthy, and lush garden. Nothing can ruin a beautiful garden faster than a lack of water. Water annual and perennial plants regularly, applying about one inch of water per week. Camellias and rhododendrons require regular watering in late summer, as they are now developing buds for next year's flowers. Lawns and turf require frequent watering in hot weather to prevent dormancy, while trees and shrubs need roughly two inches of water per week in dry conditions.

The most important tip is to water your plants slowly and deeply, ensuring the roots receive adequate moisture. This can be achieved with a drip irrigation system as it efficiently delivers water straight to the root zone of plants. A drip irrigation system on a timer is a more convenient and economical way to perform your watering tasks.

The Bottom Line

A few basic steps can help ensure that your garden thrives through late summer and all year. These 15 tips for late summer gardening and a dose of little hard work will keep your garden flourishing and let you enjoy the fruits of your labor far into the fall. Stay on top of garden tasks, including watering, weeding, pest control, and propagation techniques such as perennial division and seed collection. Stay busy throughout harvest time to preserve your yields and remember to plant cool-season crops for fall enjoyment.

Whether you need tools for planting, digging, pruning, efficient watering, weeding, or harvesting, you can find a premium collection of garden tools and irrigation products at DripWorks. Our tools and accessories will make your gardening experience much easier. If you want to learn more about fall gardening and growing vegetables, visit our Gardening Blog section and growing guides for additional resources.