Sunday, September 16

Late season gardening

Fall is not the time to give up in the garden. It's the time to get going.

After the heat and dryness of summer, it's easy to count the gardening year 'ended.' Instead, take a cue from Father Richard Pighini of Bourbonnais and revive your tired borders with seasonal color.

The cooler nights of fall invite two things -- sleeping with the windows wide open and questions about "when is it too late to ___ in the garden."

Whether you fill in that blank with "fertilize," "prune" or "plant," typical answers are often fraught with some of the most pervasive misconceptions about gardening.

In order to de-mystify late season agronomics, gardeners need to understand how what we do now impacts not only a plant's winter survival but also its performance next spring.

Woody plants
For most woody plants, the period of active growth is coming to a close. Texture changes in the twigs and foliage now and a soon-coming shot of seasonal color signal the mass storage of carbohydrates in many deciduous species. Planting, transplanting and maintenance pruning can all be accomplished more easily and with less shock to most woody plants during this resting phase. (The exceptions to that rule are azaleas and rhododendrons, which are best planted in spring in our area.)

If you purchase bare-root shrubs and trees this fall, be sure to give their roots a good soak as soon as you get them home, then plant them promptly and mulch them well before freezing weather.

Roses
Roses are busy in the fall, giving armloads of blossoms sometimes rivaling their spring display. They also tend to sprout unwelcome new stem growth--even without extra feed--so don't give them with liquid fertilizer after September 1st. Instead (for roses as well as other deciduous shrubs or trees), dress them with bone meal. Aged wood ashes and greensand each provide potassium (K) for stem and root strength. After the ground freezes, lightly work in compost, well-rotted manure and other organic nutrients as a side dressing.

Except for maintenance pruning (spent flower heads and damaged branches), wait until spring to prune roses. (You want to see how much of the plant makes it through the winter first.) And, whatever you do, steer clear of those awful Styrofoam cones! Usually put on too early and left on too late, they'll prevent the plants from hardening off naturally and effectively cook them during warm spells--provided they don't blow into your neighbor's yard first! So, declare your home a cone-free zone. Grow rose varieties that are appropriate for our USDA Zone 5 and, if you must grow more tender selections, mound 12 inches of soil around their crowns after the ground freezes.

Perennials
Hardy perennials are also slowing down now, so if you're going to divide existing plants or buy new container-grown ones, the time from August through early October is ideal. But don't wait too long. Sensitive species planted too late will not root properly. And anything planted during October will need to be surrounded with a two- to three-inch layer of loose mulch to prevent winter heaving caused by alternate freeze and thaw cycles.

Bearded iris, daylilies, peonies, hosta, oriental poppies and other perennials are often available as bare-root plants in the fall. If you buy them, they will need to be coddled both before and after they go into the ground because their roots and buds are often dried out from improper handling and display by retailers. If at all possible, try to purchase these plants the week they become available.

Potted perennials establish more easily, so I keep my investment of late-planted, bare-root specimens to a minimum, risking only the "must-haves" or those shipped directly from a grower.

Old-fashioned perennials and biennials such as sweet William, Iceland poppy, Canterbury bells, foxglove, columbine, Shasta daisy and others can be seeded directly in the ground now, but no later than the end of September. They need time to produce plants large enough to overwinter.

Annuals
After the ground freezes hard, scatter seeds of cool weather annuals like larkspur, nigella (love-in-a mist), annual poppy, rudbeckia, calliopsis and clarkia to induce vigorous germination in early spring.

Bulbs
Bulbs are always better planted as soon as they become available. I've risked plantings in early December and have had good results, particularly with tulips. But if you play, you can pay--especially with narcissus, lilies and other bulbs that require a longer rooting period.

Lawn
Plant and feed grass seed until the end of October and keep in mind that once you water it, you "own" it. You'll have to water daily until the seedlings emerge because once you water you activate the rooting process. If you have a large area to seed and will be busy with other tasks, wait for the rains and begin to water only after they cease.

Vegetables
You can have fall salads if you plant lettuce and spinach through September. You can also plant them after a freeze and get a jump-start on next spring's salad bowl. The seeds will germinate once the soil warms again.

Whatever you plant this fall, feed it. Just don't drown the plants in a liquid fertilizer that contains high amounts of nitrogen (N). You don't want soft, "unscheduled" growth coming on before a freeze. Nitrogen stretches out plants' cell walls, making them weaker and more vulnerable to bursting during winter. Instead, either amend the bed before you plant or backfill it with organic matter like compost, well-rotted manure or commercial garden soil blends (not topsoil). All of these contain nitrogen, too, but in far lower, and safer, amounts. You can also work bone meal (which decomposes over the winter to provide phosphorous (P) for strong buds and flowers) and Milorganite(r) (which provides a slow release of smaller amounts of nitrogen) into planting areas at package recommendations.

A lifelong gardener, Robert F. Gabella has been involved in the horticulture industry since 1983. With an AAS in ornamental horticulture and a BA in business management, Bob is an Illinois Certified Nursery Professional, an independent consultant, hybridist, writer and photographer. He also tends prize-winning gardens at his Villa Park home.