August Garden Calendar

Home / Garden Calendar / August Garden Calendar

Garden Calendar for August

Keep the weeds pulled, before they have a chance to flower and go to seed again

Tools and Equipment August Upkeep

  • A mousetrap attached to the wall of the tool shed can be a glove trap. Gloves hung there will dry quickly and can be easily found.
  • Check hose connections, pipes, and valves for water leaks. Even a small dribble can waste hundreds of gallons of water in a day.
  • Use an old, metal, tire rim for hanging your garden hose. Paint it the same color as your house or shed, and fasten it to the side of a building near the spigot.
  • Go over all the cold frame sashes and greenhouse glazing, replace broken glass, putty, and repaint.
  • If you do not have a cold frame, build one now.

Growing Food in August

Note: The last date to sow sweet corn for the year is August 1st

A serious disease to be aware of is late blight disease of tomatoes and potatoes. It travels on wind currents and is favored by hot, humid weather. This fungus forms large, dark, oily-looking blotches on the leaves. Entire plantings will turn brown and die within a week to 10 days of infection.

It can only be prevented by treating every week until the end of the season with a fungicide. For organic gardeners, fungicides containing copper should be used.

If your plants succumb, bag them and dispose of them in the trash after letting the bag sit in the sun for a couple of days. Do not compost diseased plants or you run the risk of having blight disease again next year. Infected potatoes need to be completely destroyed by May of next year to prevent re-infection of the new crop.

  • Start seeds of beans, beets, spinach and turnips now for the fall garden. Spinach may germinate better if seeds are refrigerated for one week before planting.
  • Savory can be used as a salt substitute in vegetable dishes.
  • Cure onions in a warm, dry place for 2 weeks before storing.
  • Broccoli, cabbage, and cauliflower transplants should be set out now for the fall garden.
  • Comfrey makes a great addition to the compost pile. Its succulent, green leaves are rich in nitrogen that aids in the break down of dry material in the compost pile.
  • Stop watering garlic and harvest it when 4 or 5 leaves are still green. Lift garlic bulbs gently from the soil (do not pull them) and brush off dirt; store them in a dry, dark place to cure for up to 6 weeks.
  • If squash and cucumber plants show powdery mildew, cut off affected areas.
  • One way to preserve herbs is to freeze them in water. Chop the herbs into an ice-cube tray, cover them with water, and freeze. Store the cubes in plastic bags in the freezer. Add these handy cubes as you prepare soup or other dishes.
  • Many herbs self sow if the flowers are not removed. Dill, basil,and
    sage produce seeds that fall around the parent plant and come up as volunteers the following spring.
  • Every weed that ripens seed means more trouble next year. Control weeds before they go to seed.
  • Remove and dispose of tomatoes showing signs of late blight such as water-soaked spots on the leaves, stems or fruit.
  • Fruit trees and small fruits: Harvest fruit when ripe; pears are an exception and should be harvested when full-sized but still hard. Apples are ripe when the seeds turn brown; blueberries are ripe 2 to 3 days after the entire berry (including the end next to the stem) turns blue. Clean-up, fertilize and water June-bearing strawberries after harvest to encourage the formation of next year’s fruit buds; remove weak, old, and crowded plants and narrow rows to 8- to 12-inches wide. Prune out second-year raspberry and blackberry canes (canes that just fruited) after harvest. Trellis first-year canes of trailing blackberries unless you live at a higher elevation.

Lawns and Landscaping in August

  • Contrary to popular belief, a brown lawn isn’t necessarily a dead lawn. Grasses go dormant in times of drought, but will quickly return to life with the fall rains. If a lush green lawn is important to you, and you don’t mind mowing, water it regularly, and deeply. If a water shortage is expected, or you hate tending to grass, you may choose to just let your lawn go dormant, and water it as seldom as once a month. Raise the cutting height of the mower. Taller grass cools the roots and helps to keep the moisture in the soil longer.
  • Consider using gray water for lawn and trees.
  • If you irrigate your lawn, consider reducing overall lawn size to save water. For example, try joining trees into beds with shrubs and ground covers. Also, try to eliminate hard-to-irrigate lawn areas, such as narrow strips between a walkway and a building, or irregularly shaped areas.
  • To maintain a healthy lawn and reduce the potential for water contamination, it is important to fertilize at the right time. Fertilize cool-season lawns (Kentucky bluegrass, fescue, ryegrass) in the fall. Fertilize warm-season grasses (bermudagrass, zoysiagrass, centipedegrass) in the summer.
  • Plants signal their need for water: turfgrass lies flat after being walked, on and many plants loose their shine and droop a little.
  • When watering lawns during hot weather, do it early in the morning. Otherwise, much of the water will evaporate from the grass before the plants get to use it. To further avoid excess evaporation, use a sprinkler that produces large drops of water instead of a fine mist.
  • Every weed that ripens seed means more trouble next year. Control weeds before they go to seed.
  • Among the cool-season grasses, tall fescue consumes 10 percent more water than bluegrass. Rye grass uses approximately the same amount of water as bluegrass. Grass needs watering if footprints remain visible, or the overall color turns gray-green.
  • If you plan to do some landscape planting this fall, now is a good time to decide on the plants to use and how to arrange them. Since the average American family moves every five years, it makes sense to buy the largest plants you can afford and enjoy them now.
  • Be sure to mow the lawn before going on vacation. If you will be gone over two weeks, arrange to have it cut while you are away. If you don’t, too much of the top growth will be removed at the next mowing. Removal of more than 1/3 of the growth at one time weakens the plant.
  • Plan to rejuvenate or plant home lawns in the fall.
  • If you wish to kill grass and weeds growing through cracks in patios, garden walks, or driveways, be extremely cautious. Many weed killers will leach into surrounding areas and damage your ornamentals or lawn. Pulling the weeds is the safest action, but please don’t use a contact herbicide containing glyphosate. Try plain white vinegar instead.

Perennials, Annuals, and Bulbs for August

»Two Easy-Care Perennials Need Periodic Dividing in August

  • Late-blooming perennials, such as Helianthus, Helenium, Heliopsis, and Rudbeckia, make great color displays in the fall landscape.
  • Looking for a refreshing color combination for late summer and early autumn? Try white garlic chives Allium tuberosum with pink turtlehead Chelone lyonii. Be sure to remove the seed heads of the garlic chives to prevent its invasiveness.
  • With a little watering and mulching, most fibrous-rooted perennials can be moved during any season. Move them in some of their own of soil, and don’t let them wilt. Fleshy-rooted and tap-rooted perennials, however, are best moved when dormant.
  • White Baby’s Breath, Gypsophila paniculata ‘Bristol Fairy'(perennial), and lavender statice, Limonium tataricum angustifolium (annual), make great round fillers for the full-sun, perennial border.
  • A superb fall perennial is the native Gentian Gentiana septemfida lagodechiana. Abundant, brilliant, dark-blue flowers are featured on 2 foot stems. Give it sun to part shade and moist, organic soil with pH 6.5 to 7.
  • Start selecting your favorite bulb varieties now by searching out bulb catalogs. It is time to order so bulbs can be planted this fall.
  • Stonecrop sedum Sedum spectabile is a succulent, pest-resistant perennial which grows about 18 inches high. Flat clusters of magenta-pink flowers open in late summer, attracting both honeybees and butterflies. Since its flower heads turn reddish-bronze and persist into winter, this easy-to-grow plant can be the backbone of the fall garden. The flower clusters are also attractive in dried arrangements. The cultivar `Autumn Joy’
    is outstanding.
  • For dried winter arrangements, flowers with petals in bright yellow, orange, pink and blue colors preserve best. Red and purple become darker and less attractive; white flowers usually become buff or tan in a short time.
  • Gold and silver chrysanthemum Chrysanthemum pacificum has a compact habit, making it great for ground cover, edging, specimen, or container planting. Its clusters of golden, button-like flowers and gray-green leaves with a silver margin give the plant its name.
  • During hot, dry, August days, avoid deep cultivation in your flower beds. Loosening the soil under these conditions reduces water uptake by increasing loss of soil water and damaging surface roots. Plants often look much worse after cultivation than before.
  • Some unusual flowers you may see thriving in the heat of August include acidanthera (also called Abyssinian Gladiolus) which bears fragrant, white flowers with dark-lilac centers and resembles gladioli; crocosmia, 24- to 30-inch tall yellow, orange, or scarlet flowers; and Galtonia candicans (summer hyacinth) with a loose, white, hyacinth-like inflorescence.
  • The best time to buy chrysanthemums is in late summer as soon as they become available. For a longer blooming period, choose plants that are just coming into bud instead of those already in full bloom.
  • If the cutting garden looks bedraggled, clear out the annuals that have finished blooming or are overgrown. Mulch empty areas to deter weeds.
  • Oriental poppies can be safely planted, transplanted, or divided this month. Plant these hardy, long-lived perennials in well-drained soil in full sun.
  • Take cuttings of favorite annuals or sow seeds in pots for winter flowering indoors. The following bedding plants root easily: coleus, geraniums, impatiens, wax begonias, and fuchsia. Plant calendula, ageratum, marigold, stock, impatiens, and snapdragon from seed.
  • Petunias vary their growth habits according to temperature and day length. At temperatures of 62 degrees F and below, petunias will be branched, bushy, compact, and multi-flowered. From 63 to 75 degrees F, day length affects growth habit. If plants receive less than 12 hours of sunlight at these temperatures, petunias will be single-stemmed and have only a single flower; with more sunlight, petunias branch and increase flowering. At over 75 degrees F, day length has no effect, and plants will always be tall, leggy, and bear few flowers.
  • Plant autumn-flowering crocus, sternbergia, colchicum, and other fall-flowering bulbs as soon as they become available at garden centers. Crocus and sternbergia need full sun; colchicum can be planted in areas receiving light shade.
  • Colorful, plastic golf tees can be stuck in the ground to mark the location of dormant plants, such as spring bulbs or perennials.
  • Don’t let your hybrid, annual flowers go to seed. This weakens the plants and reduces bloom. In addition, the seed is not desirable to save because the resulting seedlings usually will be very different from the parent and often of poorer quality.
  • Bulbs that will do well in full sun with little water in summer include crocus, native violets, King Alfred daffodils, and bearded iris.
  • Keep roots of lilies cool for best growth. Unless foliage of surrounding plants shades the roots, mulch the ground with grass clippings or similar weed-free material.
  • Keep tall flowers staked, and remove dead stalks.
  • Dis-budding chrysanthemums produces larger blooms. Most mums, except spray types, respond well to disbudding.
  • Select a good site for spring flower bulbs. For daffodils, dig the soil 12 inches deep in a sunny location. Work in a complete fertilizer and compost.
  • Sow annuals for winter flowering indoors if you have a greenhouse or bright southern window. Calendulas bloom well and last a long time. Browallia, mignonette, ageratum, marigolds, snapdragons, and many others also are good indoor subjects.
  • Since container-grown plants have a limited area from which to absorb water, plants in a sunny location may require watering several times a day. Check plants often to avoid water stress. This additional watering may leach nutrients from the media. Biweekly fertilization may be necessary to maintain vigor.
  • Many plants in the flower border will make excellent house plants this winter. Among the easy-to-maintain indoors are begonia, coleus, geranium, and ivy. If they are already being grown in containers, it is a simple matter to bring them indoors. Start moving them in at night when the temperature drops below 60 degrees F to maintain their vigor and flower production. Locate plants where they receive sunlight equivalent to what they
    received outdoors for optimum bloom. If you are planning to take some garden plants indoors to provide for early fall bloom, use a sharp knife to root prune them now to a size a little smaller than the pot. Remove all buds and flowers, and cut back the top growth severely. Water well until ready to lift.
  • Remove bedding plants that have finished blooming for the season. Replace them with hardy annuals or mums.
  • Do not mulch dormant oriental poppies. They prefer hot, sun-baked ground while resting.
  • Cut strawflowers intended for dried flower arrangements when the blooms are only half open. Tie small bundles of the flowers together, and hang them upside down in a well-ventilated place to dry.
  • Plant bulbs of the hardy amaryllis or magic lily in August as soon as received. They will produce foliage in the spring that dies down by late summer. Clusters of six to nine lily-like, pink flowers borne on 3-foot stalks appear in August. The bulbs will live almost indefinitely and grow better if not disturbed.
  • Check on water needs of hanging baskets daily in the summer.Wind and sun dry them much more quickly than other containers.
  • Do not allow phlox to go to seed. Seedlings do not come true to parent color and may overtake your planting, giving the impression that the parent plants have reverted.
  • Order your spring-flowering bulbs now. A good guideline to use is ‘biggest is best’ in regard to bulb size. Be careful about so-called “bargain” bulbs as they may be small or of inferior quality.
  • If your container annuals pass their prime, remove them and plant new ones. Add more soil mix, thoroughly blending it with the leftover soil. Add a slow-release fertilizer according to the manufacturer’s directions to feed the new flowers throughout the months ahead.
  • Take 6- to 9-inch-long cuttings of roses for rooting, using a sharp knife. Remove all but the top two or three leaves. Insert the cutting 4 to 6 inches deep in well-prepared soil in bright light. Firm, water well, and cover with an inverted glass jar to conserve moisture. Be sure the cutting does not receive direct sun, or it might overheat.
  • Plan changes in your perennial plantings now. Autumn is usually the best time for moving and dividing perennials since the gardening pace has slowed considerably. Add new bulbs to your design at the same time. Peonies, bleeding heart, and oriental poppies grow better if left undisturbed, so plan to work around them.
  • Many self-sown seedlings of hollyhock, larkspur, columbine, Sweet William, etc. are appearing now. If the parent plant is not a hybrid, the seedling should come true to type.

Trees, Shrubs, and Ground Covers in August

Late summer is NOT a good time to prune trees and shrubs because pruning will stimulate new growth. That new growth will not have enough time to harden before it turns cold. Late January and February are the best times to do major pruning.

  • Summer blooming shrubs should be pruned for shape after they have finished flowering. Remove any dead or diseased branches.
  • Look for the flowers on Franklin trees Franklinia alatamaha this month. Solitary white, fragrant, 3-inch blossoms; showy fall color; and gray bark (often with vertical fissures) make this 10 to 20 foot tree an excellent landscape choice.
  • The Oneida Viburnum, Viburnum dilatatum x V. lobophyllum ‘Oneida,’ a National Arboretum introduction, features summer bloom periods in addition to its May bloom time and showy, dark-red, fall fruits in addition to its fall foliage.
  • Order peony roots now for planting in September. Plant about a month before the average first frost date in your area. Planting should be completed before the first killing frost occurs.
  • Mulched shrubs may not develop mature stem tissue where they touch the mulch. To harden stems so they can withstand early frost damage, remove about 2 to 3 inches of the mulch from the base of the stems in mid-August.
  • Avoid deep cultivation around evergreens that have roots near the ground surface so roots are not damaged.
  • If azaleas look chlorotic (pale-green to yellow) check soil pH. They need acid soil because alkalinity locks up iron needed for green color. Sulfur reduces soil pH.
  • If the leaves of euonymus turn yellow and drop, check the stems and undersides of the leaves for tiny, needle-like, white insects and a scattering of small, brown, shell-like shapes. This is euonymus scale (males are white; females brown). Climbing euonymus is more susceptible than most upright forms. Contact your local Extension office for approved control methods.
  • Inspect trunks and branches of dogwood for injured bark or fine dust being pushed from burrows in trunks by borers. Contact your local Extension office for control recommendations.
  • Keep newly planted trees and shrubs well watered.
  • Clean up fallen rose and peony leaves. They can harbor disease and insect pests over the winter if allowed to remain on the ground.
  • Root cuttings of woody shrubs and evergreens, such as azaleas, holly, and hydrangea, at this time of year.
  • Leaf miner larvae tunnel inside leaves, leaving whitish trails as they move about. Holly, boxwood, and locust are particularly susceptible to damage.
  • Powdery mildew diseases attack a great many ornamentals, most often in late summer when the days are warm and nights cool. Some mildews, particularly those on roses, apples, and cherries, also are increased by high humidity. Prevention by proper cultural techniques is the first defense. Grow resistant varieties; space and prune plants to improve aeration and lessen shading; water early in the day and at the base rather than on leaves; and reduce nitrogen applications to avoid excessive, late-season growth.
  • Water shrubs deeply once a week during August. Many plants, including camellias and rhododendrons, are starting buds for next season’s bloom at this time. Immature berries of hollies and pyracantha may drop if the plants are water stressed.

Indoor Gardening August

  • To keep your cat out of your potted plants, generously sprinkle the soil with pepper. It works, without harming either cat or plants.
  • Inspect your house plants for signs of insect damage. Pest control is much easier and safer while the plants are outside for the summer than after you bring them in this fall.
  • Look over the house plants that are summering outdoors to see that they are not suffering from lack of water.

Miscellaneous Gardening Reminders for August

  • Use organic mulches around trees and shrubs and in flower beds. Mulch conserves water, keeps down weeds, moderates soil temperatures, and reduces runoff and erosion.
  • Before deciding to use a pesticide, diagnose the problem. Be sure to consider factors such as severe cold or heat, waterlogging or drought, lawn mower damage, carelessly applied herbicides, etc. Pesticides will be useless for these kinds of plant damage.
  • Beware of non-traditional fertilizer products on the market, such as soil activators or conditioners, nutrient release agents, soil innoculants, foliar sprays, and others. Most have little-to-no nutritional benefit for plants. Buy only those fertilizers with a guaranteed analysis and those proved by university research to be effective.
  • Low-growing plants and ground covers can be cut with a rotary lawn mover. If you have been careful to control insects and diseases in your garden, the shredded plant material should not cause any problems in your garden and is a practical way to maintain the soil organic matter.
  • If water puddles during irrigation, the sprinkler is putting out water faster than it is being absorbed by the soil. Calibrate your sprinkler to water more slowly.
  • Do not bury or spread used motor oil on the ground as it will prevent anything from growing in that location for many years and may contaminate nearby water sources. To dispose of it, take it to your community recycling center. By law, communities must have such a center, which may be located at an auto service or repair
    station, or at any station that sells or changes oil. Diesel fuel, brake and transmission lubricants, lamp oil, and kerosene can also be brought to the recycling center.
  • Many bird species, including chickadees and woodpeckers, nest in tree cavities. You can help them find homes in locations you enjoy bird watching from by drilling an occasional 2-inch diameter hole in a few trees. Locate each hole under a large limb. Drill at a slight upward angle to keep out water.
  • Plants more often wilt from a lack of oxygen than a lack of water. When the soil is compacted, the plant’s tender feeder roots and root hairs suffocate. The problem is compounded when the well-meaning gardener assumes this is a sign of water stress and immediately irrigates. Well-aerated soil, enriched with
    organic matter, allows air and water to circulate freely about the root system creating a vigorous plant.
  • Pulling out plants that have gone past their prime is an important method of preventing a build-up of disease and insect problems. Plants suspected of virus and fungal diseases should be removed and burned, if possible. The longer they are left lying around in the garden, the greater the chance for carrying over problems to next year.
  • Weeds can tell you at a glance what kind of soil you have in your yard. Sheep sorrel indicates an acid soil, goldenrod indicates an alkaline soil, and sedge or bindweed indicates poor drainage.
  • To conserve water, don’t move debris from the driveway and walkways with a spray of water; use a rake or broom.
  • Lack of water, especially when coupled with intense heat, slows down many biological processes in plants. This is called heat dormancy, although lack of moisture is as responsible for it as the heat. Plants compensate for the stress by relative inactivity. Ordinary cultural practices, instead of being beneficial, can induce further stress. Fertilizers will burn dry root hairs; pruning can force the plant to use reserves to make new growth; and pesticides may be toxic to dry foliage.
  • Many plants look wilted on hot afternoons even when there is moisture in the soil. Their roots can’t take up water fast enough to compensate for the water being lost through the leaves. If there is enough soil moisture, plants will recover by late afternoon. If they don’t perk up, water deeply.
  • In a National Gardening Association study, it was discovered that school children who participate in a garden-based curriculum out-performed other students in science comprehension and attitudes. If your child’s school doesn’t have a garden program, consider getting one going or at least involving your children in
    gardening at home.
  • An experiment at the University of Massachusetts demonstrated that a Hubbard squash can lift a John Deere tractor. As it grew within a set-up of springs and beams, the squash raised the tractor off the ground. Now if only that power could be harnessed for garden work!
  • Perhaps you’ve seen ads for various time-release watering crystals for mixing with potting soil. They absorb many times their weight in water and supposedly release that water gradually, allowing you to neglect your routine watering. Well, ‘taint so, at least for one brand tested in recent university research. While spider plants did grow better in soil including the crystals, Boston ferns showed no improvement, and both species required watering just as often, whether the crystals were included in their potting mix or not.
  • Researchers have been doing field tests of genetically engineered tomatoes that carry a gene for production of a protein from Bacillus thuringiensis (Bt), the bacteria used to kill many caterpillar pests. The resulting plants resist attack from tomato hornworm and fruitworm. As the worms eat the plant, they eat the
    protein and poison themselves. This development is still several years from commercial applications.
  • Bt Bacillus thuringiensis is used by many gardeners to protect cole crops from chewing caterpillars. A new strain of this bio-insecticide will be available soon to control Colorado potato beetles.
  • White flies are attracted to yellow, so use yellow sticky boards to reduce their populations.
  • Do not add weeds with ripened seed heads to the compost pile. Many weed seeds can remain viable and germinate next year when the compost is used.
  • Many counties have local fairs. Be sure to enter your vegetables, flowers, crafts, and other items in the competitive exhibits for ribbons and prizes.
  • By the time the seed catalogs arrive in January, you may have only a vague idea of what this year’s garden was like. Make notes now so you can have a better garden next year.
  • There are many resources for gardeners contemplating the creation of an historical garden. Local historical societies often have valuable records, photographs, and engravings. Libraries at many universities, botanical gardens, and horticultural societies have numerous books – and some maintain extensive collections of old seed catalogs. Horticulturists at public historical gardens often will be immensely helpful. Dozens of specialty seed companies and nurseries are springing up to meet the demand for “antique” plants.
  • To keep your gardens attractive, continue to dead-head (trim off) spent flowers and weed as necessary. Be sure to save your SEEDS!

Gardening is an exercise in optimism.
Sometimes, it is a triumph of hope over experience.
~ Marina Schinz