Fall planting: shrubs and perennials
Fall is one of the best times of the year to plant shrubs and perennials. Plants set out now will have four months or more of cool temperatures and moist soil before encountering summer drought. Dry and very warm weather after planting is perhaps the biggest cause of new plant loss, even when the planting is done properly.
Fall planting also places the gardener ahead of the seasonal work curve. Planting deferred until spring is often postponed altogether because there are so many other garden tasks that demand our attention in spring and early summer. Almost a whole year is gained by planting in autumn.
Best time for fall planting
When is the best time to plant in autumn? The sooner the better! With the first fall rain last week, there is no better time than now. But even if we are short on rain in the next weeks or month, it is easy to add water to planting holes ahead of transplanting and, if necessary, two or three times thereafter to carry the plant through until the fall rains come.
The extra time gained by early fall planting – even if it is but a week or so – is important because the more fully plant roots become established before chilly or freezing weather, the more certain is the success of the planting. Warm, moist soil is ideal for transplants.
Planning the planting
Ornamental shrubs are a good place to start when you plan your fall planting. From the middle of September to the middle of November, the soil is still warm from the just ended summer and there is little likelihood of a freeze to set transplants back. Evergreen shrubs will become permanent features, so planning where they are to go should not be done in a hurry. Shrubs with ornamental foliage or with colored berries or bark are just as beautiful as those which flower. They brighten the landscape during the fall and winter when the deciduous flowering shrubs have lost their beauty.
Shrubs are available for all sort of purposes – hedges, windbreaks, screens, masses, low and tall borders, single ornamental specimens – from the stiff formality of a closely clipped boxwood or privet hedge to the naturalistic abandon of our native ceanothus or manzanitas planted against a wall or a boundary line, with every appearance of having grown there naturally.
Even if you are planting only a few shrubs, take care to select those that bloom at different seasons of the year. With just a handful of different shrubs or perennials set out around a yard, flowers can be in bloom throughout the spring, summer, fall, and even winter. To estimate the numbers of shrubs required for a bed or border of a given size allow about five feet each way for taller sorts and three feet for lower.
A good principle to keep in mind when placing groups or individual specimens is to maintain what landscape architects call the “open center.” Do not set plants indiscriminately here and there, breaking up a lawn or open space, or abruptly terminating views from the front porch, patio, windows or other frequented places. Keep your shrubbery plantings at the outer margins, and be careful to use low growing shrubs so as not to cut off some nearby attraction or distant vista.
Preparing the soil
As a rule, shrubs are not particular in regard to soil, but it is important that you prepare your plant’s new home as best you can. Several years’ supply of nourishment can be incorporated into a hole before transplanting. Add bone meal and a fertilizer with phosphorous and potassium to the bottom of each planting hole before setting the plant in place. If your yard has not been previously planted or if you have inherited a neglected space, rototilling or turning the soil is a good investment of time. Adding aged steer manure and well-rotted compost to planting beds is always the best practice. Where individual specimens or small groups are to go, you can simply dig out and enrich holes of suitable size. Where hard subsoil is encountered it may be advisable to spend extra time to loosen the soil.
The compost and manure should be worked well down below the surface of planting beds; a couple of good forkfuls and two or three handfuls of a mixture of bone meal, phosphorus, and potassium to each hole where shrubs will go is not too much. If you can allow a few days to a week between preparation and the actual planting, soil amendments and fertilizers will become more available for newly set plants.
Planting the plants
From the nursery, properly grown plants will come to you with a mass of fibrous roots. Setting shrubs in their nursery pots in a tub of water for a few hours before transplanting will allow roots to plump up with moisture before being set in the ground. It is best to plant as soon as possible after plants are purchased; but if for any reason they must be held for a few days, keep them under cover and out of the wind. If planting must be delayed for a week or more, take out individual plants and heel them in a trench so that their roots do not dry out.
Firm planting is very important for fall planting – make sure the soil is tucked in around roots and solidly patted firm so there is no give. Roots need to make solid contact with the soil to receive the soil moisture and nutrients that will ensure growth. Plants that are not set firmly in place will not be ready for the strong winds that come with winter storms.
At transplanting time do not expose the roots to wind and sun. Keep the roots covered with moist burlap if they are going to sit outside the nursery bucket for more than a minute or two. Any broken or bruised roots should be cut back to clean hard wood. Deciduous trees and shrubs which flower after midsummer should be lightly trimmed back after planting. Shrubs that flower early in spring have already formed their buds, and pruning means fewer flowers the first spring, but if many of the roots have been removed, so that there seems to be too much top in proportion, it is best to sacrifice part of this first crop of flowers to make more certain of the ultimate success of the plant.
Add water to the bottom of the hole before the plant is set and again after it is about half filled with earth. Make sure that the soil is well pressed in about the roots as the hole is being filled. Do not fill the hole up level and then make it firm by pressing on the top. The top inch or two of the soil should be left loose to act as a mulch. Most shrubs should be set slightly deeper than they were growing at the nursery. Tall specimens which appear wobbly should be immediately staked and tied with bits of soft cloth or fastened with pieces of old rubber hose to prevent injury from wind.
Steve Albert is the author of The Kitchen Garden Grower’s Guide available at Amazon.com. He teaches in the landscape design program at the U.C. Berkeley Extension. He lives in Oakmont.