The late summer garden is full of challenges, but keeping things fresh involves a good mix of regular maintenance, planning, and even planting new selections. As summer heat meets dry or wet conditions, depending on where you live, climate variables impact the garden.
The temperature may range from heat waves to cool spells, and as gardeners, we’re accustomed to riding the waves. Fortunately, well-adapted plants do the same.
Summer’s end presents simple, streamlined tasks not meant to overwhelm the gardener. It’s a time of transition when you can enjoy the fruits of your labor while taking measures for the next season.
Late summer sets the stage for cool-season plantings, from crops to ornamentals. Don’t forget to soak up the garden’s late-season beauty from a shaded porch or canopy while you plan future arrangements. Here are a few more recommendations to keep things fresh!
Weather Fluctuations
Adjust your watering schedule and practices based on the shifting weather conditions.
Late summer brings variable temperatures and weather patterns. In some regions, temperatures start to mellow, while others are still two to three months away from frost. Rainfall varies, with summer storms in the south and east and dry conditions in the western U.S.
Continue to water regularly in August. Your plants may look languid, but regular moisture sets them up for a fall display, a final flush, or preparation for winter dormancy.
Changes in moisture and hot conditions make plants susceptible to pest and disease damage. Water deeply, rather than frequently and shallowly, to support healthy roots. Avoid overwatering, which leads to stress and fungal issues.
At this time of year, watch for spider mites, which thrive in hot and dry conditions. Spray plants with a hose early in the day to knock them off stems and, if they become a problem, a horticultural soap or oil.
Revisit Fertilizer Schedules
Fertilizer applications will vary from species to species as temperatures shift.
By late summer, many warm-season plants expend most of their energy and take a break until temperatures cool. With a high heat factor and slowing growth, altering your fertilizer schedule is helpful for lasting plant health and even a second flush.
Stop fertilizing flowering shrubs like roses and hydrangeas. As plants slow and move toward winter dormancy, they don’t need to direct energy toward new growth or flowering. Stop at six to eight weeks before the anticipated first frost date.
Fertilize any new seasonal plantings and crops with a low-grade organic fertilizer or related amendments like compost, seaweed, and blood meal. As they establish, new plantings benefit from the nitrogen, phosphorous, and potassium boost.
Continue to fertilize the turf until mid-August. Stop adding nitrogen at this point.
Planting Gaps
While much of the garden is still thriving, a few plants might not withstand summer. Pluck spent annuals, seasonal crops, and perennials to improve the appearance of beds and containers. This creates a clean look, highlights the remaining plants, and makes room for infill plantings.
Infill
Choose varieties that can tolerate both heat and cold.
Fill in gaps with select perennials and annuals. Opt for those with an extended bloom time or foliage interest for autumn. Choose adaptable selections, as late summer is a stressful time to plant in many growing areas. Plants that bridge hot and cool temperatures are good options.
In northern climates, it’s time to plant cool-season annuals and divide perennials. In late summer, divide irises and lilies across growing zones.
Start Cool Season Crops
Start cool-weather seeds in trays or plant directly in the ground.
August and September are ideal for looking ahead to fall and getting a jumpstart on crops. As with infilling annuals and perennials, opt for heat—and frost-tolerant crops for an autumn harvest or to overwinter.
Late summer seeding includes parsley, lemon balm, mustards, kale, radishes, carrots, and turnips. Direct sow adaptable crops or start them in shaded seed trays.
In warm climates (zone 7 and higher), you may still be able to fit in a final round of successional crops like bush beans. Make sure to choose varieties that are quick to mature so you can enjoy them before deep frost sets in. A benefit of late-season planting (other than the extended bounty) is that some pests are near the end of their active feeding cycles.
Add Grass Seed
Check for bare patches where you can place seeds.
While infilling annuals, perennials, and seasonal crops, check bare areas in the lawn. By late summer, grass may show dry patches caused by insects, disease, water fluctuations, or sunscald.
Now is the time to fill in those patches by scattering seeds. Target the trouble spots for ease of application and concentrate the seeds where needed.
Mow grass regularly to a height of two to two and a half inches. This height keeps it looking lush and leafy for moisture uptake while protecting roots from heat, sun, and seasonal conditions.
Fading Flowers
Deadhead annuals and perennials regularly. Deadheading enhances the plant’s appearance and encourages flowering into the cool season. Removing spent blooms redirects energy from seed production into further flowering.
There are exceptions to deadheading in late summer, especially as we move into September. Consider rosehips for winter interest and seeds for next year’s blooms.
Selective Deadheading
Selectively deadhead plants that you don’t want to self-sow.
For reblooming roses that produce rose hips, it’s important to stop deadheading in September. Six to eight weeks before your anticipated frost date works well. Gardeners mark Labor Day as a good rule of thumb for stopping cutting faded petals.
This gives time for the remaining flowers to set rosehips, which provide colorful interest and forage for birds and wildlife. It also signals the plant to conserve energy from flowering as it prepares for winter dormancy.
Cut transitioning hydrangea blooms for dried arrangements. Alternatively, let them brown on the stem for extended interest. Depending on the integrity of the bloom, the tawny, papery petals add lasting texture. It won’t affect the shrub and is more of a “gardener’s choice” about aesthetics.
For annuals and perennials, exceptions to deadheading at summer’s end are plants we want to produce seed. Annuals and perennials drop their seeds and, depending on the selection and climate, overwinter to reemerge in spring. Don’t deadhead the plants you want to self-seed in the landscape.
Going to Seed
Flowering plants produce seeds that can be dispersed on the wind or act as food for animals.
Letting flowering plants go to seed has numerous benefits, one of which is continuing the display in future seasons. This works well in naturalized, cottage, and informal garden areas. It ensures you’ll have plants well-suited to your site’s growing conditions.
Another key benefit of letting plants go to seed is food for songbirds and other wildlife. Seeds provide energy stores in fall and winter when food sources become leaner.
Natural seed drop also benefits future colonies. Some perennials rely on winter temperatures to germinate. A period of cold stratification is necessary to form strong plants. Echinacea, rudbeckia, and catmint are seeds that require cold stratification.
Seed pods and heads also provide lasting winter interest. During a quiet time in the landscape, seeds add textural interest.
Lastly, seed production allows us to collect and store seeds for future use. Seed saving is helpful for heirloom or favorite food crops, especially if they’re hard to come by or from pass-along selections.
Seed saving is cost-effective and helps promote genetic diversity among our crops. Protecting genetic traits is a benefit of growing heirlooms bred for their fruiting and growth characteristics.
Leggy or Shaggy Plants
While it’s not the time for heavy pruning for most plants, the late summer garden benefits from light trimming and shaping. Cut out brown and crispy stems from annuals and perennials to improve their appearance and help revive growth. Clip herbs to restore their form and shape for another round of leafy stems. Take inventory of shrubs and trees for fall pruning and remove dead limbs or branches.
Light Pruning
Some plants benefit from light pruning before cooler weather.
Hedges and topiaries tolerate a final trim in late summer. Trimming allows new growth tips to harden off before winter. Prune lightly, as we’re not encouraging new growth in the summer heat and before cold temperatures.
If needed, lightly prune hydrangeas and roses, depending on the variety, saving any heavier shaping for fall and winter. For roses, remove any thin, whippy canes, especially in climbers.
Flowering shrubs that set buds on old growth (the previous season’s stems) need any shaping before the buds set. Buds develop soon after flowering, so it’s ideal to prune them more heavily in early fall if necessary. Pruning is not usually needed for either woody shrub. Remove damaged, diseased, or dead canes at any time of year.
Harvest Herbs
Refresh herbs by trimming them down to manageable shapes and sizes.
Herbs with sprawling stems and runners may be unruly or sparse in areas. Now is an excellent time to get them back in shape, encouraging bushy forms. To refresh herbs, trim stems to promote a bushy habit. They’ll experience a flush of fresh growth.
Some herbs, like basil, live in water indefinitely. Stick a few clippings in water on a sunny windowsill for winter use, or propagate them from the cuttings to enjoy in an indoor container over the winter. If the herbs don’t have enough fresh, pliable, woody stems for cuttings in late summer, wait until fall’s new growth.
Drying the trimmings is an easy way to preserve them. Hang herbs like sage, parsley, thyme, rosemary, oregano, and mint in a warm, dry, sheltered spot. The leaves are handy for autumnal and winter dishes.
Dried flower heads and shrubs that collect snow look beautiful in the winter.
As we assess plants at season’s end, consider the winter garden. We know to let lingering roses go to hips and perennials go to seed where appropriate. Leave interesting seed pods, dried flower heads, and branches to spark interest in the cold months.
Keep ornamental grasses intact for their showy plumes and fine-bladed foliage. They make beautiful autumnal accents that last into winter, even in their brown, dormant stage. As seeds provide aesthetics and food sources for birds and small mammals, plants offer them shelter.
Consider upcoming additions, like trees and shrubs, to add structure. Fall is just around the corner and ideal for planting trees, shrubs, and perennials. Plan for maturity, ensuring plenty of space for fully-grown specimens. Consider shrubs and trees with multiseason appeal, including winter interest.
While everything is mature, consider what you’d like to change about the garden. Pictures help with future planning, a cozy activity on chilly winter days.
Worn, Untidy Beds
A simple sweep of garden beds and edges spruces the look while improving growing conditions. Lifting weeds, removing fallen material, and refreshing mulch revives the end-of-season display and sets the foundation for fall.
Pull Weeds
Pull out weeds to reduce their spread and keep them manageable when spring comes.
Weeds thrive anytime, and late summer is prime for their seed production. Pulling weeds before they drop seed helps future plantings. As with other plants, weed seeds overwinter for emergence in spring.
Remove roots and seed heads to lessen the spread of a multiplying weed population. This promotes less competition among valuable garden selections, improves air circulation, and reduces the spread of diseases among plants.
Clean Up Debris
Clean up fallen debris that can be harmful to your plants.
Debris harbors pests and diseases, and removing fallen leaves and petals around plants improves conditions. As an added incentive, a light rake to clear debris creates fresh-looking beds.
By late summer, garden mulch may be sun-blanched and worn. If you plan to change out of beds in the fall, hold off on fresh mulch until after planting. If not, topdress with compost or mulch to refresh the look while improving moisture retention, weed suppression, and temperature regulation.
Add the mulch after getting rid of the weeds. Crops in production mode may benefit from refreshed straw or mulch for late summer insulation.
Excess Bounty
A wonderful challenge of the late summer garden is an abundant harvest and bloom show. Hold onto the excess by preserving fresh fruits and vegetables and drying flowers for lasting enjoyment.
Pickling, Preserving, Canning, and Freezing
Preserve your harvest by pickling, canning, or other means.
August and September mean plenty to harvest, though warm-season crops begin winding down. Continue to harvest regularly to promote late-season production. Clear out spent crops to make room for new varieties.
Pickling, canning, or making sauces work well for many vegetables and fruits, from peaches and blackberries to corn, okra, green beans, and tomatoes.
Opt for freezing if you need a simple and quick way to store the summer harvest. Most fruits and vegetables benefit from blanching first to deactivate enzymes for preservation and lasting flavor and to soften their skin. Use these over the winter to recall the flavor of a vibrant harvest.
Dry The Blooms
Preserve flowers and their beauty by drying them.
If you’re not ready to part with the late summer garden colors, many perennials and flowering shrubs produce blooms that dry beautifully for long-lasting floral arrangements. Press the blooms with a flower press or dry them for preservation.
Clip fresh blooms early in the day, after the morning dew dries. Hang flowers upside down for easy drying. Once cut, remove leaves and bundle stems in small groups. Tie the stems with soft twine and suspend them in a dry, dim space. Flowers may take a few weeks to dry completely. When fully dry, they will have stiff blooms and crisp stems that snap easily.
For hydrangeas, cut blooms fresh or let them dry on the stem. In late summer or early fall, the blooms become papery and stiff. They’re perfect for clipping when their color transitions to dusky pink and green. Enjoy them on the autumnal table.
