Horticulture Report September 2019

Perennials, annuals, and bulbs

During the fall months of September, October and November, after soil temperature drops below 60°F., the bulbs of spring flowering tulips, daffodils, hyacinths, scilla, dwarf irises, anemone, and crocus should be planted. Select healthy, disease free bulbs. Add Bone meal or Bulb fertilizer into the planting hole, as you prepare the soil.

Winter pansies, flowering Kale, flowering Cabbage, and fall mums may be planted now, to give a little color to the garden when the summer flowers have faded away.

Scatter the seeds of perennials in a row or in open beds this month so that the young seedlings will be ready to be transplanted into their permanent spot next spring.

As the weather cools, perennials which have overgrown their space or become crowded should be dug and divided, or moved to a new area of the garden. New or replacement perennials can also be planted this month.

Tender bulbs should be dug up and stored in a cool, dark area after first frost.

Shrubs and trees

Fall is a good time to select and plant trees and shrubs. Fall planting encourages good root development, allowing the plants to get established before spring. If weather is dry, provide water up until the ground freezes.

Stop fertilizing your trees and flowering shrubs to allow this years growth to harden off before winter.

After you have finished harvesting your summer vegetables, plant a cover crop of clovers, cow peas, soybeans, or vetches for the purpose of plowing under next spring. These nitrogen producing plants will provide good organic matter and food for your garden crops next year, as well as helping to control weeds over the winter.


When the fall rains arrive, fertilize your lawn with a slow-release 3-1-2 ratio fertilizer.

September is one of the best months of the entire year for seeding or sodding new lawns.

If the lawn needs thatching, it can be done during the early fall.

Over seed old lawns with fresh seed to help fill in the bare spots and crowd out weeds and mosses.

House Plants

Pot up some spring flowering bulbs for indoor color during the winter. Store the pots in a cool, dark place, until new growth emerges from the soil, and then move them to a bright window.

Begin conditioning your Poinsettias and Christmas cactus to get them ready for the upcoming holiday season. Both of these plants are short day plants. Although they will eventually bloom, if you want the plants in bloom in time for the holidays they must be kept at about 65 to 70 degrees, and subjected to at least six weeks of 14 hours of total darkness per day (mid to late September). This may be accomplished by placing the potted plant in a closet or unlighted room, or by covering the plant with black cloth, black plastic over a frame or a cardboard box. The plant must then be returned to the light each day and given a minimum of 4 hours of direct sun, or 10 hours of bright light. The application of a 0-10-10 fertilizer this month and again next should help encourage the development of flower buds, then feed your plant every 2 weeks with a high nitrogen fertilizer once color has begun to show.
Christmas cactus needs the same general care, with the exception that they require cooler temperatures of about 50 to 60 degrees.

Continue to watch for insect or disease damage and take the necessary steps to control the problem.

Odds and ends

Mark your perennials with permanent tags, or create a map showing their locations so you’ll know where and what they are when they die back at the end of the season. This will help you to avoid digging up something you intended to keep when you plant bulbs and plants this fall and next spring.

One last effort at weeding will help to improve the appearance of your garden throughout the winter.

The birds will soon begin their winter migrations. Give them a helping hand by providing them with some food for their long journey. No one likes to travel on an empty stomach, and you may even persuade a few of them to stick around for the winter, if they know they have a reliable food source!

Continue to watch for insects, slugs and snails, or disease damage throughout the garden, and take the necessary steps to control the problem.

Zone 5

  • Plant winter-hardy pansies and fall annuals (calendula, dianthus, ornamental cabbage and kale)
  • Plant tag teams of perennials and spring-blooming bulbs that will complement each other or bloom in sequence next season
  • Water trees and shrubs when rainfall is scarce to “winterize” them
  • Dethatch and aerate the lawn
  • Deadhead chrysanthemum plants to keep flower buds forming through the fall
  • Clean out rose beds; apply fungicide; leave hips for winter color and bird food
  • Prune summer-bearing raspberries
  • Mow back strawberry plants; remove weeds and remulch
  • Move tender houseplants, etc. indoors after rinsing and repotting, and set up a grow light to supplement natural light

Next month will be time enough for some bulb planting; though it is better for the daffodils to go into the ground as soon as the bulbs are delivered.

Roses also may be ordered in September for delivery and planting during the month. If you are a rank amateur, consult a reliable source on the details of planting, for it is an exact and important business. Lack of planting knowledge may cost you your new roses

The hardier house plants which still remain in the garden must come into the house before danger of frost, Lift the pots, prune, and keep on the porch for a few days before taking inside, so that the shock of removal may be less violent.

If any plants are growing in these and borders which you desire to take in for winter use, the earlier they are potted the better. They may need severe pruning, and the pruned portions may be used for cuttings to make new plants. Root these in flats of moist sand and transplant later into pots of mixed loam, sand, and peat.

Perennial seedlings, which were planted in July or August, may need plenty of watering during September, and also the cutting bed and the compost heap.

The lawn may also need artificial watering if it is to present a green, velvety appearance in the spring. Early September is not too late to plant grass seed where it is needed.

Late-blooming flowers such as chrysanthemums, dahlias, and asters need plenty of water, fertilization, and perhaps spraying during September to insure fine bloom later on.

Rose bushes may be thankful for September spraying and watering if rainfall is scanty, as some of the finest blooms come during the cool, late autumn weeks.

Peonies can be transplanted best early in September. Purchase plants now. Do not divide or replant old-established peonies unless they show signs of flowering- less vigorously in their original positions.

Iris, gaillardia, hardy asters, phlox, and bleeding heart, can be transplanted successfully in September.

Pansies, English daisies, and myosotis (forget-me-nots), which were planted in August, are ready in late September for a light winter protection. Evergreen boughs laid across the bed are most effective for this purpose, though good substitutes are excelsior or salt hay held down lightly by a few pruned tree branches.

Though we cannot always count on the seed, gathered from our own garden flowers, it is worth while to gather those of fine specimen blooms for planting in spring. In this way we may perpetuate some especially fine plants. Dry the seeds thoroughly in the sun before placing them in small manila coin envelopes. Mark plainly with name, date, etc. These envelopes can be filed like index cards.

After the seeds are harvested, dead flower stalks may be collected and burned. This will help to prevent the spread of disease, which may have attacked the plants.

Gladiola bulbs should be harvested, tops cut off close to bulb, and dried in flats a short time until surface moisture has disappeared. Store in a cool, dry cellar in the same flats in which they were dried.

Tuberous-rooted begonias must also come up with a clump of earth attached to the tuber before danger of hard frost. If the foliage is still alive, cut it to prevent rotting and store the tubers in a cool cellar.

Evergreens demand our attention. This is a good month for pruning and cleaning. Dead wood can be easily discovered during this dormant period. Bagworms may be removed, and sulfur applied if red spider is still present.

Most hardy deciduous shrubs, which bloom in spring and early summer, can be transplanted during this month.

Watering must not be neglected especially for newly set trees and shrubs. The roots are not yet thoroughly established in their unaccustomed positions, and need more than a normal amount of moisture.

How and When to Divide Hosta

If you have Hosta that are growing so tightly that the center of the plants has died out, it’s time to divide them.

Division is a simple plant propagation technique that is exactly as it sounds. You dig the plant up and divide
the root ball into multiple pieces. This technique only works with plants that have multiple crowns emerging
from the ground. Most perennials fall into this category, flowering shrubs and trees do not.

If you have Hosta that you would like to divide, you can do so now, about 30 days before they go dormant. That
way the soil is still warm enough for the new divisions to establish some new roots before winter.

Or you can wait until spring. Just wait for the plant to start growing. As the new growth just starts to emerge
divide them then, not after the new growth opens up with leaves. Once they produce leaves it’s best to wait
until fall.

To divide them simply dig up the root ball and with your spade cut the root ball into multiple pieces. Replant the pieces. It’s as simple as that.