By Laurie Brown
It’s September, and the gardening season is winding down. Time to start putting things to bed, raking leaves, and… planting. Yes, planting.
It’s the perfect time of year for getting many plants in the ground. Cooler temperatures mean less wilting of plants and of gardeners. Rains mean less hose wrangling for you. Fall tends to be less demanding as the weeds are tapering off, unlike in spring when they are exploding. And a lot of garden centers have sales on plants now, trying to get inventory down for less work through winter. You can plant up to six weeks before the ground freezes; cold air temperatures are fine as long as the plants haven’t been kept warm in greenhouses.
Everyone is bringing out the spring blooming bulbs right now; it’s actually a tiny bit early for planting them. You don’t want warm soil to spur top growth; you only want root growth from them. But you want to be getting perennials, shrubs and trees in now, so that they get their roots dug in and settled before cold shuts them down and frost heaving starts. You can help prevent heaving on late plantings; I’ve taken rocks and put them on the root ball to hold them down—this also helps keep deer from pulling them up. But it’s still better to get them in early. This is a good time for dividing and transplanting spring bloomers, too; they’ll be ready to bloom next year if divided now. But leave the late bloomers like asters alone; divide them in spring (of course it’s all right to plant potted asters now). And it’s the best time for dividing and planting peonies. They won’t bloom next year, but they will get a good start.
Potted plants frequently are root bound when bought at this time of year. Make sure to loosen the roots; unwind circling ones and spread them out. If the plant has lots of fine roots making a “block” of root mass, take a sharp knife and shave about a half-inch off the root ball to expose new little growing tips. Add aged compost to the hole, and plant at the same level it was at in the pot. Cut back tall, floppy plants and remove dead flowers. Do not fertilize, except for phosphorus (which soils in our area usually don’t need). You don’t want any tender new growth on the top of the plant! Make sure plants are kept well-watered up to planting time, and water deeply when you plant them.
In fall, all plants need deep watering if rains are not regular and heavy. It greatly increases their chances of surviving winter. Write down what you plant where or make a map—frost heaves the plastic tags out of the ground at least half the time and they go wherever plastic tags go when they disappear.
Do not mulch plants until after the ground freezes. The idea is to insulate the frozen soil so it does not go into freeze/thaw cycles and heave the plants out. A heaved out plant is prey to both dehydration and exposure to lower than 32º F air temperatures.
When there is no snow on the ground, take a walk in the garden, check for heaved plants, and gently replace them. If you buy some plants and have to wait a bit before planting, DO NOT bring them into the house or garage. Keep them out in the weather that they will have to live in. They need tough love.