September Garden Tips

September days are here, with summer’s best of weather and autumn’s best of cheer.
~ Helen Hunt Jackson

In the Flower Garden

Pansies planted this month will stay in bloom until the ground freezes. Mulch them for winter protection and these hardy pansies will be back in flower when the warm days of spring return. They are great companions for spring-flowering bulbs.

Plant frost-hardy plants like garden mums, asters, flowering kale, flowering cabbage, and pansies as you remove tender annuals from beds and borders. Mums are a great value for the spectacular show of color they provide.

For fun try taking cuttings of your favorite geraniums before first frost. Dip these cuttings in a rooting hormone and place in good, lightweight soil. Water in well, but let soil go fairly dry between waterings. 

When digging up your cannas, dahlias, and gladioli, use a felt tipped pen to write on the bulbs what color each bulb is so that you will be able to identify which is which in the spring. Store these and other tender bulbs in moistened vermiculite or peat moss in a cool area and protect them from freezing over the winter.


The best selection of bulbs is now. Don’t forget bulb food or super phosphate when planting your tulips, daffodils, crocus and other spring-flowering bulbs. Plant colchicum and fall-blooming crocus now which will bloom for you this fall. 

The easiest way to plant bulbs at the proper depth is with a bulb planter or an auger which attaches to your electric drill. When planting bulbs the pointed end of the bulb is positioned upward.

Plant bulbs under groundcovers like thyme or veronica for a great combination of flowers and backdrop. This is a low maintenance technique for combining plants for a succession of color. 

Plant small, early-flowering bulbs where they can be seen from indoors, since they bloom when it is usually too cold to enjoy them outside. 

Perennials & Roses

September is an excellent time for planting perennials! The temperatures are cooling down and the soil is still warm, which allows rooting to take place. Plant your perennials at the same time you plant bulbs. You’ll be able to place perennial plants between your
bulb groupings for color from spring to fall. 

Divide peonies and daylilies at this time of year. Stop in for a care sheet for instructions for both of these beautiful perennials. Remove any foliage with fungal diseases such as powdery mildew and rust. Discard in the trash. Cleaning up now will help prevent a recurrence of the problem next year. 

September Lawn Care

Lawns grow best in spring and fall. They will benefit greatly from two more feedings. Fertilize your lawn with Green Thumb Lawn Fertilizer by mid September. Green Thumb Winterizer should be applied in mid October. Your lawn will be nice and green in the spring.

Bindweed, dandelion, and other perennial weeds will be moving food reserves down to their roots now. This is a great time to use Weed Free Zone to kill these invasive weeds, roots and all. 

Core aerate your lawn in mid to late September, so that winter moisture can soak in. 

September is an excellent time to seed your lawn. Cooler temperatures mean less stress on you and your lawn. 

Trees & Shrubs

September is a great time to plant trees, shrubs, and vines. The soil is still warm
and good for root development and to get the plant established. Water in well
and cover with mulch to retain moisture.

Be sure to pay extra attention to the watering needs
throughout the fall and winter months.

Don’t be alarmed if your pine trees begin dropping their older needles. It’s normal for the inner needles to yellow or brown and drop off in the fall. 

Avoid excessive pruning of trees and shrubs, because pruning encourages new growth to begin and you want the plants to harden off before going into
dormancy for the winter. 

If you had insect problems on your trees and shrubs, whether they be aphids or borers, an application of Ferti-lome Tree and Shrub Systemic Insect Drench, will greatly reduce their population. Apply this fall, and your plants
will be protected for a whole year. 

Watch for leaf color to change on the trees and shrubs around your neighborhoods. Then come into the nursery and select the plant of your choice and the color that you want. Genetically trees and shrubs may have different shades
of fall color, so this is a great time to pick your plants. 

Rake up fallen apples, crabapples, and other fruit from the ground
to prevent insects from overwintering. 

You can reduce the amount of bruising and damage to apples and other fruit by using a long-handled fruit picker to reach the highest branches of fruit trees. 

Vegetable Gardens

Harvest potatoes when the foliage browns. It is better to harvest potatoes when the soil is fairly dry, using a pitchfork or spading fork to gently loosen the soil around them. Let the tubers dry for a few hours in a warm place, but out of the direct sun.

Winter squash — such as acorn, spaghetti, buttercup, butternut, and Hubbard — are ready to harvest when you cannot puncture the skin with your thumbnail
and the stems are dry and begin to shrivel.

Gently turn pumpkins and gourds to prevent soft spots. Place three or four inches
of straw under your pumpkins to prevent damage to the bottoms.

Before first frost dig up herbs like chives, rosemary and parsley, place them in pots in a south-facing window for seasonings all winter.

When onion tops start to yellow, bend them over to divert the plant’s energy to the bulb. After the tops turn brown, lift the onions from the soil and let them dry in the sun. Once the skins are dry, cut the stems and store the onions in a cool, dry place.  

Make notes or a journal to keep records on which of your vegetables did best and were the most prolific and which vegetables did not perform well. Next year, focus on planting varieties which performed well for you.  

Spray or pull up all weeds before they go to seed. This will save a lot of time
and aggravation next spring.

When Early Frosts Threaten…

Water deeply and thoroughly before cold weather – hydrated plants
will do better when an early frost occurs. If plants do show some signs of frost damage, wait a few days in order to give them time to recover
before pulling them up. 

Harvest fruits and vegetables prior to a hard freeze. 
Pick your green tomatoes — tomatoes will continue to ripen after being picked green. Place them in a single layer in a cardboard box, being sure they do not touch each other and cover with a newspaper. Place boxes in a dark, cool place, but don’t forget to check often as the tomatoes will ripen sporadically.  

Just as a blanket will keep you warm, it will also keep your plants warm!
Frost blankets will protect a late-season vegetable garden from cold damage
and ensure that it continues to produce after the weather has cleared.
Avoid using plastic coverings — plastic attracts the cold & may harm plants.

When temperatures drop into the low 30s, be sure to disconnect hoses from spigots.  Don’t forget to drain your hoses, birdbaths, and other water holding items
to prevent them from freezing or cracking.


Check your houseplants carefully for insects before you bring them back indoors. 

Plant amaryllis bulbs the end of this month for blooms at Christmas.

Continue to supply your hummingbird feeders for the fall migration show.