September Garden Calendar

September Gardening Chores

Go Shopping! Most folks think this is the end of the gardening season, but to be honest it is perfect gardening time! You can plant all winter hardy plants, giving the roots time to establish before the ground begins to freeze. This time of year nurseries discount their stock and it a great time for bargains.

Divide your perennials. Most perennial plants (except those that are currently blooming) will divide and transplant well during this cool, moist season. Do not transplant past October for the best results.

Plant spring bulbs. Late September through October is the best time for planting your
favorite Tulips, Daffodils, Crocus, and more. They can be planted until the ground is hard with ice.

Remove diseased foliage. Any diseased or insect infested foliage should be burned. (not composted) Although proper composting should kill most diseases, it is not advisable to add them to your own
compost bin. Contact your county recycling center for instructions on how to properly dispose of non-compostable vegetation.

Tools and Equipment for September

  • Take special care of any wooden handles on your tools. Handles should be smooth (sand if needed). Apply a coat of bright-colored, water-resistant paint to keep wood from drying out, prevent shrinking or splitting, and make them easier to see if left out in the garden.
  • Buildings and wood fences should be painted as often as necessary to maintain an attractive appearance and preserve the wood. The cool, dry days of fall are an ideal time for this activity. The job will enhance the beauty, usefulness, and value of your property. It is also a fine contribution to community beautification and civic pride.
  • To keep from spreading diseases and insect pests, sterilize old flower pots by soaking overnight in a solution of one part bleach to nine parts water.
  • When using a cold frame to extend your harvest season, be sure to close the top on frosty nights to protect the plants from the cold. When the sun comes out the next morning and the air warms, open the cold frame again.

Vegetable, Fruit, and Herb Gardening in September

  • Harvest! If you took the time to plant a fall garden, many good veggies will be ready for harvest this month. If you happen to get more produce from your happy plants than you anticipated, make sure you still get everything removed from your plants. If you are short on time I’m sure you could get friends, family, and neighbors to help! Not only are these goodies too tasty to let rot, but if they do, you are encouraging a huge host of unwanted pests- insects, rodents, birds, fungi, bacteria, you name it, it will come if you let your harvest get out-of-hand. So do your garden a favor and eat!
  • Dig new garden beds for next spring. Incorporate plenty of organic matter, such as leaves, and leave the soil rough to allow good water penetration. Freezing and thawing will break up heavy clay soils. Plant a cover crop, also called a green manure, to increase the soil’s organic matter content.
  • Be sure your cold frames and greenhouses are airtight and ready to go for the cooler nights. Daytime temperatures can become very hot in these locations, so be sure to open and close windows as needed. Consider investing in a self-opening elbow for your windows. They can save many trips back and forth to the garden
    throughout the fickle autumn weather.
  • Pot up chives, parsley, and other herbs, and bring into the house to extend the growing season.
  • Green manures for cool seasons can be sown.
  • Strawberry runners should be rooted and transplanted by the end of the month.
  • To insure a good crop of big bulbs next fall, plant garlic cloves this fall. Be sure to cover the garlic plot with a layer of organic mulch.
  • Don’t prune rose hips yet if you plan on saving them for jellies or medicinal purposes.
  • Bring in your more sensitive plants as the nights get cooler. Stevia, ginger, and other tropicals don’t like colder weather. Many other herbs can stay outside until the first frosts.
  • Garlic is harvested when the tops die down. To prepare garlic for long term storage, cure the bulbs for four to six weeks in a warm, dry, shady location where there is good air circulation. Pile bulbs no more than two to three deep. After curing, store in a cool, dry, well-ventilated spot.
  • Keep basil, parsley, mint, sage, balm, and borage producing by pinching out the seed pods. Herbs can be used fresh, frozen, or dried. Wait until the dew has dried to cut a few stems, tie a string around this little bouquet, and hang in a cool, dry place until completely dry. Crumble and place in a jar for use during the winter.
  • Plant lavender seeds outside in the fall. The seedlings will appear in early spring.
  • Herbs can be dried quickly in the oven. Place your oven on the lowest heat and let them dry for an hour or two. Remove them from the oven, let cool, then test to see if the leaves are crisp. If not, return them to the oven for a bit. Store in jars in a dark place so they will keep their color and flavor.

Lawns and Landscaping in September

September is a terrific time to work on a cool season lawn. Cool season lawns consist of tall fescue, fine fescue and Kentucky blue grass. Planting, over seeding, fertilizing and aeration are jobs that need to be done this month. Most lawns are tired of the heat and low moisture conditions from the summer but with some guidance most can be re-energized.

  • Seed the lawn. Mid September to early October is the best time for seeding a lawn (Early spring isthe second best!). Lawn grass germinates at the greatest rate when daytime temperatures are
    near 60° (15° Cel). and when soil is moist but not soggy.
  • Remove leaves from lawn. We have always done it- but do you know why? Okay, it does look good, but it also helps prevent Snow Mold, a common fungus that often attacks and kills grass that is smothered by moist deciduous leaves.
  • Don’t retire the lawn mower when the growth of your lawn slows down this fall. As long as the grass continues to grow, it should be mowed.
  • Early autumn is the best time of the year for the sowing of grass seed. Grass sown in spring is often killed by hot, dry, summer weather. For more vigorous growth, spread a very thin mulch of clean straw over newly seeded areas. The straw shades delicate seedlings from the hot sun and helps preserve moisture in the soil, yet lets enough light through for germination. By the time cold weather arrives, the grass is fairly well established and ready to grow and thicken early the following spring.
  • Healthy green grass outside the windows of your home can cool the breeze off hot pavement by as much as 10 degrees F.
  • All of those grass clippings and other organic matter that you compost really do add nitrogen to your soil. Ten (10) pounds of nitrogen are released gradually over a year’s time for every one percent organic matter in cultivated soils.
  • When landscaping for energy efficiency, choose evergreens for the north and northwest sides of the house where they will block winter winds without limiting winter sun. Block early morning and late afternoon summer sun by planting deciduous trees to the east and west of the house, including the southeast and southwest
    corners. Don’t plant shade trees to the direct south of the house; the summer sun is so high in the sky it will shine onto the house over all but the tallest trees, and the trees would block cooling, southernly breezes.

Want to know more about mowing your lawn?
The Complete Guide to Mowing Your Grass Like a Pro

Perennials, Annuals, and Bulbs for September

Plant fall blooming mums. Without a doubt, Chrysanthemums are great for brilliant fall color. Bonus! …if you plant them early enough to establish a decent root system, most of the hardier
types will survive the winter.

  • It’s a good time to take cuttings of woody plants and shrubs.
  • Wintergreen Gaultheria procumbens makes a great ground cover (2 to 4 inches tall) for sites with sun or light, mid-day shade. This evergreen plant is tolerant of wet soils; loves acid soil (pH 4 to 6.5) with abundant organic matter; and features white, summer flowers and red, fall berries in addition to pleasing, leathery, green foliage. Gaultheria is a source of wintergreen oil and is a folk toothache cure due to the presence of a compound similar to aspirin.
  • As you select your flowering bulbs to plant this fall, keep in mind that larger caliber bulbs give big, showy displays, but cost more. Smaller caliber bulbs usually are less expensive, with a smaller show, but are great for brightening nooks and crannies in your yard.
  • Start taking cuttings of your annual plants to bring indoors and carry through the winter. Geranium, coleus, fuschia, and other plants do best when stem cuttings are rooted and kept in pots indoors through the winter. Be sure to place pots where they receive plenty of light.
  • Fall is a good time to invest in crocus; scilla; narcissus; glory-of-the-snow; and other easy-to-naturalize, hardy bulbs. A mild winter produces an exceptionally fine growing season in the Netherlands and results in a record-breaking crop of flower bulbs that are reported to be of superb quality.
  • Bring hanging baskets or pots of begonias indoors for the fall and winter. Return outdoors in the spring.
  • Have on hand some heavy paper or cardboard boxes to cover tender garden plants on the first nights of frost. Often if tender plants can be protected from early frosts, they will bloom for several more weeks.
  • Bright-colored flowers from spring-blooming bulbs can bring interest to a neutral setting in early spring. Set some in the rock garden or alongside a brick wall this fall. Many of the dwarf species available are ideal.
  • If you are not sure which end of the bulb is the top, plant it on its side. The stem will always grow upright.
  • When planting ornamentals around the perimeter of a building, leave room behind the foundation plants to paint, put up screens, etc. A tree too close to the house may clog gutters with leaves. Roots can invade drain fields, crack walks, and pierce foundation walls. Leave plenty of space between buildings, houses, and tree plantings.
  • Plant lilies this fall for many years of beautiful flowering. Modern hybrids are available in many colors and grow from 2 to 6 feet tall. American-grown hybrid varieties have less trouble with virus disease than the old species types.
  • Place rooted cuttings in the cold frame. Unless frost threatens, ventilate frames freely to harden young plants in preparation for overwintering.
  • Now is the time to move perennial plants started from seed in midsummer to the nursery row or to their permanent spot in the garden. Mulch after the first hard frost.
  • Soak bulbs of winter aconite in water for a few hours before planting.
  • Every three to four years, separate crowded lily-of-the-valley crowns. Replant 3 inches apart.
  • When planning next year’s fall garden, consider the versatile and carefree daylily as a source of fall color to complement chrysanthemums and fall asters. There are several varieties of daylily that will bloom in August and September.
  • Mark the spot in your garden where asclepias are so you will not dig them up next spring. Plants are late to break dormancy in spring, but once established, they should not be disturbed.
  • To avoid damage from mice or other vegetarian rodents, plant the bulbs in cans. Cut both ends from large fruit-drink cans. Bury the cans to their rims. Fill about one-third full of soil, place one bulb in each, and cover to the surface with soil.
  • Perennial flowers that will bloom in September include Biglow sneezeweed Helenium Biglovii, hardy asters, hardy chrysanthemums, showy stonecrop Sedum spectabile, false dragonhead Physostegia virginiana, bigleaf sea lavender Limonium latifolium, and great azure sage Salvia Pitcheri.
  • If you enjoy growing wild flowers, collect seed for your garden from many of the summer-flowering types now.
  • Plant peonies now, but make sure the crowns are buried only 1 1/2 to 2 inches below ground level. Deeper planting keeps the plants from blooming.
  • Root cuttings of such annual bedding plants as begonias, coleus, geraniums, and impatiens. These can overwinter in a bright window and provide plants for next year’s garden.
  • As the nights become cool, caladiums will begin to lose leaves. Dig them up, allow them to dry, and store them in a warm, dry place. This space can be replanted with Christmas peppers or Jerusalem cherry plants that are easy to grow from seed in pots or with mum transplants that have been grown to flower size.
  • Freesia corms can be planted early this month for December flowering. Plant them 2 inches deep in pots, then place outdoors in a shady place. Move pots indoors to a cool location when night temperatures begin to dip below 45 degrees F. Freesias bloom in 10 to 12 weeks from planting.
  • Perennial phlox should be divided about every third or fourth year. Early fall and early spring are the best times to plant and transplant them. Divide big clumps into thirds.
  • In cooler areas, it is time to dig gladiolus corms as the leaves yellow. The tops should be cut off 1/2 inch
    above the top of the corm immediately after digging. After digging, dry the corms (about 10 to 20 days), separate the large corms from the smaller ones, and store them in damp peat moss at 40 to 45 degrees F where there is good air circulation.
  • Establish new perennial flower beds; dig, divide, and replant overcrowded beds of cannas, daylilies, violets, and shasta daisies. Spread a liberal amount of organic matter and bulb fertilizer evenly over the area. Mix this into the soil at least 6 to 8 inches deep. Space divisions at least 1 foot apart in all directions so that root competition will not be a problem for several years.
  • To plant bulbs, loosen the soil and make a hole with a trowel or bulb planter. Don’t mash the bulb into the soil or you may damage the basal plate (bottom of the bulb), causing it to rot.
  • Outdoor ferns should be planted in early fall for best results. To have a healthy fern garden, add several inches of leaf mold or peat to the soil before planting.
  • For early blooms in May and June next year, certain annuals can be sown now, including larkspur, nigella, calendula, Shirley poppies, annual scabious, and coreopsis. Sown in the open, they should be well established by the time the cold weather comes.
  • Dig out the list of spring-flowering bulbs you made last spring, and start getting them into the ground so you can be among the blissful rather than wistful as next winter snows begin to melt. If you did not get a list started last spring, a few bulbs to consider for starters are snowflake, glory-of-the-snow, early crocus, snowdrop, and winter aconite.
  • Plant new Madonna lilies as soon as they arrive. Do not plant them deeper than 1 inch from top of bulb to ground level.
  • Allow a few of the seeds of your favorite delphinium and hollyhock to ripen on their stalks. When mature, plant the seeds at once in a garden bed where they will grow into husky little plants that overwinter well.
  • Plant roots of both garden and tree peonies in September or early October so they will have time to become established in the soil before winter. Dig a hole 18 inches across and 18 inches deep for each tuber. Space the holes so that the plants will be at least 3 feet apart. Make sure the roots are buried only 1 1/2 to 3 inches below ground level. Deeper planting keeps the plants from blooming.
  • As you plant your spring bulbs, remember that a mass planting of one flower type or color will produce a better effect than a mixture of many colors. Flowers of bulbs stand out more vividly if displayed against a contrasting background. For example, white hyacinths among English ivy, yellow daffodils against a ‘Burford’ holly hedge, or red tulips towering over a carpet of yellow pansies.
  • Sowing seeds of hardy annuals, such as sweet alyssum, pinks, and sweet peas, now will give the seedlings time to get established and develop good root systems before the coldest part of winter. This gives them a head start on growth and flowering next spring.
  • A generation or two ago, gardeners overwintered geraniums as house plants. In sunny windows, the plants flowered, but usually grew quite leggy. Development of compact geraniums, such as the cultivars Hollywood and Orbit, provides incentive to try overwintering a few plants. In fact, some geranium producers are growing them as pot plants for fall and winter sales.
  • Divide lilies-of-the-valley. Mix organic matter and fertilizer into the soil before replanting.
  • Mums can be transplanted while in bloom, which makes them useful for instant landscapes in early autumn. Water thoroughly the day before (or at least several hours before) digging plants, retaining as much of the root system as possible. Dig the new hole, and gently loosen a small amount of soil from the outer soil depth. Water thoroughly after placing the plants to settle them in. As with any transplanting, it is best move mums in early morning or late evening when temperatures are cool. Monitor plants carefully for several days for wilting, and shade briefly during the hotter periods of the day, if necessary.
  • Lots of spring bulb fanciers swear by bone meal for fertilizing their planting beds, but the phosphorus in bone meal is almost completely unavailable to plants until the soil temperature reaches about 50 degrees F. Bone meal might aid your bulbs late in the growing season, but it does not aid flowering appreciably. More soluble phosphorus fertilizers may work better in spring.

Trees, Shrubs, and Ground Covers in September

  • Fall is usually cool and moist and a good time to plant trees and shrubs. Research has shown that roots will continue to grow until the soil freezes. This is true for both evergreens and deciduous plants.
  • Fall is a great time to plant and divide perennials and shrubs for next year’s garden. By planting in the fall, your plants do not endure the stressful summer heat during establishment and have time to form sufficient root systems before the onset of winter dormancy.
  • Don’t let the fall pass you by with only the changing colors of the trees to enjoy! Look for fall annuals that are tolerant of cooler temperatures. Some suggestions are snapdragon, calendula, pansy, flowering cabbage and kale, stock, viola, dusty miller, and poppy.
  • The perfect gift for the golden anniversary? Give the Golden Rain Tree, Koulreuteria panniculata, favored for its brilliant, gold, fall foliage show.
  • High fertilization of pyracantha, an evergreen shrub, produces rampant growth that is susceptible to fireblight and reduces berry production.
  • Give your perennials and woody ornamentals a fall check-up, look for weak or diseased plants. Eliminate plants that might infect or take energy from neighboring plants.
  • If your landscape area is small, select diminutive cultivars of woody ornamentals. Look for Latin names that include “compacta” or “repandenus.”
  • Wait until deciduous trees and shrubs begin to drop their leaves before fertilizing them. This signals dormancy, when no new growth will be stimulated that might not harden off prior to cold temperatures. However, roots are active until soil temperature drops below 40 degrees F, so nutrients will be taken up and used by the plants to develop a stronger root system.
  • To minimize the occurrence of black spot on roses, prune and remove infected areas. Be sure to destroy the clippings, as the disease will carry over from year to year.
  • Many balled and burlapped trees and shrubs are now sold wrapped in synthetic burlap that will not rot in the ground, resulting in a rootbound plant that doesn’t grow well if the burlap is left in place. Some of this material strongly resembles cotton burlap; if in doubt about the burlap’s makeup, cut it away from the root ball once the plant is in place.
  • Select some accent plants for your landscape that will provide autumn color. Trees that turn red include dogwood, red maple, black gum, sweet gum, and red or scarlet oak. Shrubs with red fall foliage include viburnum, winged euonymus, and barberry.
  • Allow plants to finish the summer growth cycle in a normal manner. Never encourage growth with heavy applications of fertilizer or excessive pruning at this time as plants will quickly delay their hardening process that has already begun in anticipation of winter several months ahead. New growth can be easily injured by an early freeze.
  • An easy way to propagate autumn olive bushes by seed is to plant the whole fruits soon after they ripen in the fall.
  • Tree-wound paints used after pruning are no longer recommended because they can slow healing and may promote decay.
  • If pesky seedlings of woody plants, such as elm or hackberry, are found growing in your hedge, remove them as soon as possible. If left too long, they will take over and leave gaps in the hedge when they are finally removed.
  • Rake up leaves, twigs, and fruit from crab apple trees, and dispose of them in the trash to help control scab.
  • Water newly planted trees and shrubs to provide sufficient moisture and prevent winter damage. Add a 3-inch layer of an organic mulch, such as shredded bark, around the base of plants to retain soil moisture and regulate soil temperature.
  • Stake and wire newly planted trees only if necessary. Use a piece of rubber hose around the guy wires to protect the trunk, and don’t tie the tree tightly; it needs to be able to move a little in the wind. Remember to take the supports and stakes out in a few months once the tree is established.
  • Generally, it is best for amateur arborists not to move deciduous trees before their leaves fall.
  • Needle leaf or cone-bearing evergreens can be moved now if you want to transplant them. Move plants with an ample rootball.

Indoor Gardening September

  • Do not use softened water on houseplants because the sodium accumulates in the soil and can kill the plants.
  • Dish gardens designed with several foliage species, possibly some ceramic figurines or driftwood, and perhaps sprigs of unusual fern are ideal for gifts to new mothers and dads and even grandparents on their day in September.
  • Be sure to clean the windows where plants will be this winter while the plants are still outside. The difference in light available to the plants will be significant.
  • Houseplants that have been outside all summer should be allowed to make a fairly slow transition to indoor conditions. Quick changes in environment can result in yellowed foliage and leaf drop. To avoid injury, bring plants indoors before temperatures dip below 55 degrees F. Check for insect pests before you move the plants; it is easier to get rid of pests while plants are still outside.
  • An easy indoor plant watering system can be constructed by inserting an asbestos-glass water wick into one of the drainage holes of a pot. Old nylon stockings can be braided and used instead. Set the pot on a water reservoir made from heavy plastic, such as a large-sized, whipped margarine container. Prepare the container lid by making two holes; one for the wick to reach the water and a larger one for supplying fresh water. This is a highly efficient system for carefree watering. However, the plants should be periodically watered from the top to flush accumulated minerals from the soil.
  • Don’t wait for frost warnings to move your house plants indoors. Temperatures of 50 degrees F or lower can damage many tropical plants.

Miscellaneous Gardening Reminders for September

  • Leaves will begin to fall soon. Make sure your compost bins or piles are ready to accept fresh materials.
  • Put the right plant in the right place – with the right soil, moisture, and sun or shade conditions, your plants will be healthier, and many will not need extra watering.
  • For a quick mulch, cut the plants in your vegetable and flower gardens, but leave the material in the garden to prevent erosion and provide organic matter for the soil. Use hand pruners, hedge shears, or a sickle to chop the plants into mulch-size pieces. Just be sure that the plant material has no disease or insect
  • Try planting ferns to fill in between and beneath shrubs, trees, grape arbors, and other shady spots.
    Plant in early fall for best results.
  • Wood ashes contain phosphorous, calcium, and potassium and can be placed on the garden, flower beds, or spread on lawn, but don’t overdo it. Avoid using wood ashes on acid-loving plants, such as azaleas and blueberries, because ashes raise the soil pH.
  • Fall clean-up and planting in the garden can provide enjoyable exercise on sunny days. One hour of gardening chores (cultivating, pruning, weeding) burns about 300 calories!
  • “Thigmomorphogenesis,” the response of plants to mechanical perturbation, is a common plant response to mechanical stress (wind, touch, vibration). It appears to be a plant’s method of strengthening itself to withstand further stresses. The effect also can be seen in woody plants, in which the wood of stems and branches often becomes reoriented in a way that braces the plant against prevailing winds. These effects are a hormonal response mediated by ethylene.
  • Seaweed and seafood wastes often are untapped resources for gardeners near the coast. To reduce their strong odor, these materials need to be composted. For seaweed, compost with a high nitrogen material, such as manure or grass clippings. With seafood scraps, add a material high in carbon, such as dry leaves or aged sawdust.
  • Gather ornamental grasses for dried arrangements.
  • Nitrogen fertilizer not taken up by plants can leach into the groundwater, polluting it and nearby streams and rivers. Studies at the Wye Research Farm in Maryland have shown that a rye cover crop can rapidly take up excess nitrogen from the soil (160 lbs.N assimilated per acre 90 days after planting). Nitrogen recovered by a cover crop will be returned to the soil when the cover is tilled under in spring (when crop plants can use it). In addition, a winter cover will reduce soil erosion and add organic matter in gardens. Sow winter rye at 3 1/2 ounces per 100 square feet between now and late October.
  • The Cincinnati Zoo and Botanical Garden has an interesting theme garden. It seems that Biblical, Shakespeare, or other traditional themes don’t really excite children, but the dinosaur garden is a real hit. Plan one of your own using prehistoric plants, such as dawn redwood Metasequoia glyptostroboides, maidenhair tree Ginkgo biloba, or katsura tree Cercidiphyllum japonicum, all of which date back from 150 to 270 million years. Other plants to include are bald cypress, bayberry, boxwood, fern, and larch.
  • Not only is compost good for your garden, but making and using it also is good for your community. Any leaves, grass clippings, or prunings that go into the pile don’t end up wasting space in the landfill.
  • Make a simple compost pile by incorporating some garden soil and a little fertilizer into a pile of leaves. Next spring, you will have a supply of leaf mold to improve the structure of your garden soil. To achieve faster decomposition of the compost pile, turn the pile over every month or so during the growing season.
  • Collect okra seed pods, gourds, sumac seed heads, rose hips, and other suitable material for dried flower arrangements. Air dry these materials in a dark, cool location.
  • Autumn is a good time for improving your garden soil. Add manure, compost, and leaves to increase the organic matter content. Before adding lime to your soil, have your soil tested to determine if your soil is acidic and needs lime.
  • You can help leaves break down more easily by running a lawn mover back and forth over the pile. Put the shredded leaves directly onto the garden or compost pile.
  • Get in a supply of builders sand for the winter. It comes in handy not only for increasing traction on walks and driveways, but also for making soil mixtures and for storing root crops.
  • A green manure or cover crop improves water infiltration, reduces soil erosion, reduces nutrient leaching, and promotes the growth of microorganisms. Annual rye can be sown at the rate of 1 to 2 pounds per 1000 square feet during September and October. A light fertilization with 1 to 2 pounds of 5-10-10 generally will increase plant growth.
  • Powdery mildew becomes more abundant following periods of cool nights and warm, dry days. Infected plants are covered with a white, powdery growth.
  • If infected plant materials are to be composted, be sure that your compost heap is an active one in which plant material really decays. This is evidenced by the warmth generated by the decomposition reactions in the pile. Tossing plant materials on a rubbish pile will not destroy disease organisms, but hot composting them will.
  • One of our readers sent us a delightful letter on homemade stationery that is worth manufacturing on your own if you have access to a copier machine. Enclose plants with interesting foliage shapes and colors, such as the miniature nerve plant Fittonia minima, between two transparent sheets to protect the bed of the copier. Duplicate as you would any other document. If color ink is available, it will be even more attractive.
  • Winter-ready mulch marginal plants. Some plants will benefit from some extra winter insulation
    such as clean straw or leaves. For best results and least amount of rodents and mold, wait until the ground has started to freeze.

“Always remember the beauty of the garden, for there is peace.”
~ Author Unknown

september garden calendar

The Ready Store
"The doctor of the future will give no medicine, but will interest his patient in the care of the human frame, in diet and in the cause and prevention of disease" ~ Thomas Jefferson