By now, most gardeners across the state will have experienced frost on the pumpkins, leaf fall in the woodlands and a clear sense that the growing year is drawing to a close.
Smart gardeners know it isn’t over quite yet. Putting the garden to bed for the winter leaves a clean slate for next year’s adventures. Prepping new beds, enriching the soil, eliminating weeds and pests, and protecting your plants against the frosts of winter will give you a real leg up next season. Time spent in the garden this fall will pay rich dividends when spring suddenly overwhelms you with its gardening must-dos.
Here’s a list of things to do now and things to do soon, before the biting cold of real winter weather keeps you indoors:
True annuals complete their life cycle in a single season and then die. The first kiss of frost reduces tender annuals like impatiens to mush - simply remove them, roots and all, and discard or compost them.
Annuals regenerate by setting seed, and if seed pods are left intact, many will self-sow. This works best with plants that remain close to their old-fashioned roots. Eager self-sowers include bachelor's buttons, spider flower (Cleome), annual poppies, sweet alyssum, love-in-a-mist (Nigella) and lobelia.
True lilies, daffodils, bulbous irises and crocus spring from bulbs that can remain in the ground through the winter. These can be planted as long as the soil remains unfrozen, so procrastinators, take heart – there’s still time.
Dahlias, cannas, gladioli and tuberous begonias can't survive freezing temperatures and must be dug and stored for the winter in a frost-free place like the basement. After cold has killed the foliage, lift, dry and pack tubers in a loose material like sand, sawdust, peat moss or vermiculite and store in a cool, dry spot. Wait until spring to divide tubers or propagate plants from new shoots.
Frost has already killed warm weather crops like tomatoes, eggplant, peppers and zucchini. Remove and discard or compost these. Root crops including turnips and carrots can be left in the ground and harvested as needed.
Fall is an excellent time to replenish soil nutrients. Once vegetable debris is removed, till in aged manure, compost, chopped leaves, straw or other organic material. To deter erosion, leave soil "lumpy" after tilling or sow a winter cover crop like annual rye or hairy vetch, which can be turned under in spring.
Wait until foliage has browned and shriveled to cut back perennials. When you do cut back stems, leave 6-8 inch stubs to catch leaves and snow, which helps protect the crown. Woody-stemmed perennials should be left alone until spring. These include butterfly bush (Buddleia), Russian sage (Perovskia), santolina and bluebeard (Caryopteris).
You may want to leave attractive seed heads and pods to provide winter interest. Ornamental grasses, coneflowers, bugbane (Cimicifuga), astilbe and sedum can look good as they dry and provide seed for birds.
The rule on dividing perennials goes like this: Divide in fall those blooming between early spring and late June; divide in spring those that bloom from late June to frost.
Always choose varieties that are rated for New Jersey's plant hardiness zones – Zones 6 and 7. Most of the popular roses can withstand temperatures of about 10 degrees, but extra coddling doesn't hurt.
The easiest way to protect plants is to mound soil taken from another area of the garden around the stems to the height of about 1 foot, covering the bud union or swelling where graft meets root. The soil can be removed gradually after the soil begins to thaw next spring.
Rake up dead leaves when they fall (or pluck them off, if you're inclined) and discard them. They can harbor leaf scourges like black spot, reinfecting the plant next spring.
Shrubs and trees
Late fall is actually the preferred time to plant most deciduous shrubs and trees. Dormant plant stock is easier to handle, and root growth, which continues while warmth lingers in the soil, will help specimens get established before leaves sprout next spring.
Current thinking is that soil should not be amended in the planting hole, which creates a pocket of richer soil that confines root growth. Use whatever soil you dug out to backfill the hole. Don't stake, either, unless your site is unusually windy. Subtle movement of the trunk actually prompts the stem to grow thicker and sturdier.
Save any heavy pruning for late winter or early spring. Pruning stimulates new growth, which won't have time to mature or "harden up" by winter.
Continue to mow as long as the grass is growing. Drop the mowing height back to 2 or 2 1/2 inches on the last mow around Thanksgiving to make it easier to rake leaves and to prevent fungus diseases like snow mold.
If you haven't gotten around to your fall fertilizing, do it in the next two weeks. Look for a formula in which the three numbers representing nitrogen, phosphorus and potassium have a ratio of 4-1-2 or 3-1-2. If you need lime (a soil test will tell the tale) fall is the time to apply it.