What to do in the garden in July & August

by cathym on June 30, 2020

It is the heart of summer gardening season. The Northeast sees its hottest weather in July but, August can bring hot, humid weather as well and can be unpredictable, with extended periods of rain and even cooler temperatures as garden stands begin to show pumpkins and fall mums. Below we provide you with some gardening tasks to help keep your gardens flourishing through the late summer.

Step back and look at your garden to see what is in bloom and where you lack floral color. It is the perfect time to take pictures and notes as to where you can improve next year.

Make sure tall plants and climbers are well supported in case of bad weather. Also, pruning wisteria at this time will encourage new growth and help keep it in balance with the trellis.

Water at dusk to reduce evaporation; mulch garden beds to retain moisture around plants and help keep roots cool. Always practice effective watering by watering the soil around the base of the plants rather than the foliage. Control water and sprinkler use so as not to waste water by losing it to pavement, driveway, or any other unintended area.

Newly planted trees and shrubs (deciduous and evergreen) need extra watering in dry periods. Make sure they get a good, regular deep drink that will go down to their roots. Keep an eye on them for signs of wilting, a sign they are lacking water.

Do not mow too low in summer. Mow as high as possible—that will result in a healthier lawn with deeper roots that are more tolerant of the drought and stress of summer. Slightly higher turfgrass also helps shade out the weeds. 

Regularly deadhead annual and perennials as well as roses to encourage new blooms. Cut back faded perennials to keep gardens neat. Some spring blooming perennials, such as lupine, can be sheared back hard to encourage a second flush of blooms later in the summer. Now is the time to cut back any remaining spring bulb foliage as well.

Keep containers fresh.

Check your containers. Cutting back growth in hanging baskets (i.e., petunias) can encourage new flowers and foliage to revive the display; fertilize well after doing this. Make sure you are fertilizing your containers regularly throughout the hot months. When it comes to container plants, remember the soil dries out faster, so pay special attention to make sure these plants are receiving sufficient water. Terracotta pots will particularly dry out quicker, so dampen the pots to reduce evaporation and help keep the plants roots cool.

Consider dividing bearded iris now. If your plants did not bloom well, chances are they need to be divided. July through August is the best time to do this. Using a digging fork, carefully dig around the plant, being careful not to pierce the rhizome. Once lifted, shake off loose soil or rinse it off with a hose so that you can better inspect the rhizomes for any damage. Separate the individual rhizomes. Cut the foliage to about six inches. Cut sections of the rhizome so that you have pieces about three inches long with healthy roots growing from the cut, using a sharp knife to make clean cuts. Replant, being careful not to bury the rhizome with more than an inch of soil; these plants will not bloom well if planted too deeply.

Avoid transplanting roses when the temperatures are above eighty degrees. If you do transplant them in summer, prune heavily. Water the roses slow and deep. Add mulch to help suppress weeds. 

Harvest vegetables and fruits regularly; July is a good month to harvest beets, peas, carrots, chard, lettuce, and some tomatoes. Routinely inspect your vegetable garden and prune any yellow foliage. Remove garden debris to cut down on insect or disease issues. Continue to remove suckers from tomato plants and check that they are adequately supported with stakes or cages. Water crops daily in hot weather to ensure they are consistently moist. Uneven watering may cause blossom end rot on tomatoes. Blueberries are especially sensitive to drought conditions. Feed crops with a general-purpose fertilizer. Weed regularly, since weeds can compete with your crops for nutrients and water.

In late July, consider a fall crop of snow peas, spinach, or lettuce. Other cool season crops do well in mid to late summer to give you a nice fall harvest.

Observe your garden daily. If you see a harmful pest consider integrated pest management practices: cultural, biological, and mechanical controls. Use chemical controls as the last resort. Handpick Japanese beetles using a pail of soapy water. Just hand pick or shake plants and the pests will just fall into the bucket and drown. Look at the undersides of plant and crop foliage where insects such as aphids can hide. Keep an eye out for the scarlet-colored lily leaf beetles on your ornamental lilies. Check for sticky brown larvae on the undersides of lily foliage. 

Protect bramble crops such as blackberries or raspberries from birds by installing netting around the plants.

Shrubs may require some pruning to give much needed shaping and to allow good air circulation at this time. 

Look at your containers; if they are looking a bit shabby, consider a container rehab! You can use houseplants, individual plants from the garden bed, plants from other containers, or plants on sale to give your container a fresh look. Carefully pull out those that are past their peak and replace them with fresh plants. Be sure to fertilize after replanting.

After the month of August, cease fertilizing your roses—this will help to prepare them for fall and winter months ahead.

Think about which bulbs you might like to add to your garden for next spring. Now is the time to order them. In late August, you can plant fall-blooming bulbs such as colchicums or autumn crocus as soon as they are available.

Make notes on your garden’s pros and cons. Take more photos of your garden. Do you want to make any changes or additions? Garden centers will be having sales and it could be a good time to add plants. It is a great time to plan for next year.

In a Zone 5 garden, August is the latest to consider growing edible crops for the fall such as lettuce, spinach, or broccoli. You may have to consider protecting them from the hot sun by using row covers or milk crates.

Keep mowing your lawn high. Late August into September is the perfect time to renovate a tired lawn or start a new one.

Harvest beans, cucumbers, zucchini, eggplant, peppers, tomatoes, etc. so that plants continue to produce. Peppers can stay on the plant longer to allow them to color. Consider what to do with your herbs; it is a good time to freeze or preserve them in other ways for use over the winter months.

Take cuttings of your favorite annuals such as coleus, impatiens, or geraniums. You can grow them indoors later to save for next year. Many plants, such as coleus, will easily root in a glass of water.

Consider adding a perennial fruit or fruit tree to your garden. The upcoming fall is the perfect time to plant and stock may be available on sale and could be a good money saver.

Feel free to reach out to your local Cornell Cooperative Extension office’s Master Gardener volunteers for answers to any questions you might have.

— Rosanne Loparco, John Slifka, and Ron Broughton, Master Gardener volunteers at Cornell Cooperative Extension, Oneida County



We gardeners have been waiting for spring. However, during May, PATIENCE is the rule. A common problem is planting too soon. If the soil is too cold or wet seeds may rot and roots may stop growing. 

Soil temperature should be above 50 F. If soil feels cold in your hand, it’s too cold for plants! Try making a ball with a handful of soil. Does it crumble? Great. Does it form a ball? It’s too wet.

Purchase compact, healthy plants with unopened buds that are appropriate for your gardens. Read plant tags and note the final height and width. Are they appropriate for your space? Mix compost, or other organic materials into the soil before planting. Mulch lightly around the new plants.

Planting holes should be a deep as the root mass and twice as wide. Be sure to spread or “spider” the roots to encourage root growth into the soil instead of circling, self-strangling roots which can lead to disaster.

Leave bulb foliage intact until it yellows and wilts, but remove spent flowers to prevent seed formation. The foliage is required to give bulbs the food necessary to form next year’s blooms. Spring bulbs can be moved or divided as soon as the foliage dies. Do the same for bearded irises so the energy goes into the rhizomes. Divide Virginia bluebells, bloodroot, trilliums, and other spring ephemerals when the leaves turn yellow and before they disappear from sight. 

Weeding never ends. Mulching helps. Plant warm-season annuals by mid-June, before it gets too hot for them to establish good roots. These include cosmos, marigolds, begonias, torenias, petunias, ageratum, and cleome.

Check for signs of insects (chewed leaves, puncture wounds, sticky substances, trails in leaves) or disease (yellow leaves, stunted growth, signs of fungi). Be sure to look on both sides of the leaves before buying any plant. Don’t forget to check for healthy roots. Slug control can start as soon as you can get into the garden. Take a look on top and under the leaves of tomato, potato, pepper, and eggplants for hornworm eggs (only one-tenth of an inch in diameter). Yellow trails in columbine leaves are caused by leaf miners, the larva of a genus of fly. This is more of an aesthetic problem … you don’t have to do anything OR you can remove the affected leaves.

Buy yourself at least one new plant! Consider some native plant species to help pollinators and to feed young birds. Keep newly planted trees, shrubs, vegetables, perennials, and flowers well-watered (about one inch per week.)

Try deer repellants or consider deer resistant plants. Check the Cornell website for a great deer resistant plant list. 

Cut back spring-flowering perennials such as pulmonaria and perennial geraniums after they bloom to encourage reblooming and/or growth of new foliage. Deadhead perennials and annuals to prevent seed formation and to encourage new growth and more flowers.

At the end of June, cut back perennials such as phlox, beebalm, sedum, aster, and goldenrod by one-third to one-half to control height or delay flowering. This is known as the Chelsea Chop.

Place supports over taller flowering plants so the plants can grow up through them without damage to foliage and flowers later in the season.

Spring-blooming shrubs like weigela, forsythias, and spirea can be pruned back after blooming. Cut about one-third of the oldest stems to the ground for renovation.

If growing azaleas and/or rhododendrons in higher pH soil be sure to add acidifying agents. However, don’t disturb the roots.

Mow lawn at least three inches high. This encourages deeper, healthier root growth. Leave grass clippings on the lawn to return nutrients to the soil.

The first application of lawn fertilizer, if needed, can be put down around Memorial Day. If fertilizer was applied in the fall a spring application is not necessary. A quarter to a half inch top dressing of compost adds nutrients, feeds soil microbes, and improves the water-holding capacity of the soil. 

For optimal pre-emergent crabgrass control, do not apply until soil is close to 60 degrees. Crabgrass doesn’t germinate until the soil temperature 2 inches deep is between 60 & 64 degrees. Applying when the ground is too cold is a waste of money and chemicals.

Check the Cornell recommended vegetable list for suggested and disease resistant varieties.

Plant your brassicas now: broccoli, cauliflower, Brussels sprouts and summer cabbage. Reseed bush beans every few weeks to increase production.

Plant your tomatoes, eggplant, squash, pumpkins, cucumbers, and peppers when the ground is warm to promote root growth. Usually this time comes closer to the end of May.

After direct-sowing seeds, be sure to thin the seedlings to prevent crowding and competition for light, water, and fertilizer. If plants were grown from seed be sure to harden them off before planting them in the garden.

—Carol Ann Harlos and Lyn Chimera, Master Gardeners, Erie County


A volunteer pansy shows its cute face in April

Looking out the window in March when the snow is still flying, or trying to determine in April when the ground is dry enough to dig, we may feel as though spring will never come. Even so, there are many gardening chores that can be done. This is the perfect time to tackle some of the less-than-glamorous but critical tasks that will ensure a splendid garden throughout the year. On days too messy to work outside, there are plenty of jobs for the indoor gardener.

Inspect your tools and remove any rust you find. Sharpen the edges on your cutting tools to make sure you will obtain clean cuts on shrubs and trees. Take your power equipment to get an annual servicing—this includes tillers and lawn mowers. Even though they may not be needed until later in the season, now is a good time to do in, in order to avoid possible long service waits. You can also spend this time to cleaning pots and other containers to be sure that no diseases or pests carry over into the new growing season. Soap and water and/or a bleach or vinegar solution should suffice.

Now is also the time to start seeds indoors. Resources to find the correct time to start seeds and to transplant can be found at (Gardening Factsheets) and at Cool season vegetables such as beets, cabbage, leeks, and spinach can be sown or planted outdoors in April or as soon as the ground is workable.

Containers of plants that tolerate cooler temperatures can be placed outside in a sunny location in mid-April. Plants that work well for these early container gardens include pansies, cineraria, oxalis, heuchera, and parsley. Seeing these blooms has the added advantage of chasing away the winter doldrums. The container may need to be covered if a hard freeze is expected.

As the weather improves or on warm winter days you can begin your outdoor preparations such as pruning trees and shrubs and cleaning and readying garden areas. With the leaves still off deciduous trees and shrubs, it’s the perfect time to survey them for broken or diseased branches. You can remove them along with any branches that cross each other. Prune shrubs that need to be shaped. Shrubs that bloom on new wood, like roses, can be pruned back in early spring. Shrubs that bloom on old wood should wait until shortly after blooming. Azaleas fall into this category. There’s a helpful resource for pruning at

It is also a great time to clear garden beds of leaves and other debris that has accumulated over the winter. Herbaceous perennials that were left to add winter interest to the garden, such as sedum and decorative grasses, should now be cut down close to the ground to allow for new growth. Evergreen and semievergreen perennials like heuchera and lavender can be trimmed of old leaves to improve shape and bloom. Mulching, however, should wait until the ground has warmed up in late May. And, yes, start attacking weeds as soon as they appear.

Once the ground is workable (a handful of dirt is crumbly), garden beds can be prepared for planting. Most plants need well-drained soil. Dense soil can be improved by adding organic matter to help hold moisture and nutrients. A soil test is beneficial to determine if additional nutrients are needed. Some local Cornell Extension offices, like Monroe County’s, can perform soil testing at a reasonable price. 

Use of fertilizers should be judicious to avoid runoff harming the watershed. Organic fertilizers are often easier on the environment. Your local nursery should be able to provide advice on which fertilizer to use as well as organic controls for pests, diseases, and weeds.

Lawn rejuvenation should wait until May when the ground is warm enough to germinate seed. The lawn can be prepared now by gently raking up leaves and debris. Vigorous raking at this time may pull up the grass you want, so be gentle. Fertilization of lawns should be delayed until the grass has been mowed a couple of times. Lawn care information is also available on the website in the Gardening Factsheets.

Start planning for next spring by taking a survey of your garden. Do you have any early signs of spring such as snowdrops, hellebore, witch hazel, flowering quince? What about ephemerals that appear in spring and then die back until the next spring, e.g., bloodroot, Virginia bluebells, hepatica, spring beauty, Dutchman’s breeches, and bleeding hearts? Plant some of these this year and you will be pleasantly surprised early next year when they appear to let you know that spring is coming!

The mantra for all gardeners should be “Right plant, Right place.” Take this time to get fully acquainted with the sunlight and moisture available in different parts of your yard. We all want to rush out and buy something that looks good in the nursery, but will it survive in your garden? Our growing area for perennials, trees, and shrubs is zone 6 near Lakes Erie and Ontario and zone 5 the towards the Southern Tier. Be sure to check the hardiness zone on plant tags.

Finally, both gardening and spring awaken our senses to what is different and emerging around us. By interacting with nature, we learn to appreciate what is possible and needed to make our gardens a joy to behold. We get exercise, learn to solve problems, and make decisions for the benefit our environment. Most importantly, we get to enjoy a sense of peace as we look at the natural beauty we have in our gardens.

—Bonnie Knoke, Master Gardener, Cornell Cooperative Extension, Monroe County