How to Plant Perennials in Spring or Fall
Although you can plant some perennials in your flower garden in the fall, springtime is preferable. All the conditions that perennials relish and respond to are in place: warming soil, warm sunshine, longer days, moist ground, and regular rainfall. Roots quest into the ground, taking up water and nutrients to fuel growth, and top growth — foliage, stems, and flowers — surges forth.
Whether you choose to plant in the spring or fall, you handle them all the same: Here are some tips about the proper handling of perennials:
Don't handle the plants roughly.
Don't plunk a root-bound plant into the ground. Either tease apart the roots a bit or lightly score the sides with a sharp knife, which inspires new root growth. Then you may place the perennial in its planting hole.
Don't plant perennials in waterlogged ground, or drench them right after planting. A moderate dose of water is a needed drink; too much water prohibits oxygen from getting to the roots, and the plants literally drown or rot.
When getting ready for spring planting, make sure you do the following:
Harden off the plants.
Let new plants adjust to life outdoors for a few days or a week by sitting them in a sheltered spot. Leave the plants outside for just a few hours, and slowly increase the time until they're outdoors 24/7. (Bring perennials indoors or cover them if there's a threat of a late frost.) Cover them with single layer of newspaper to reduce the light intensity and wind exposure.
Choose a cool, cloudy, or damp day to plant, or plant in late afternoon.
Plant in good soil, create a basin of soil or mulch around each plant, and give a good, soaking watering.
Check that the water drains in where you want it.
Mulch after planting.
In temperate climates, autumn is a fine time to plant many perennials. The soil and air are cooler and sunlight is less intense, so the weather's less stressful for newcomer plants. Competition from weeds isn't likely to be a big problem, either.
In some regions, rainfall becomes more regular, too, which helps provide the moisture the perennials need to start good root growth. And their roots do grow — the plants simply aren't programmed to start producing lots of new leaves or flowers at this time of year. Yes, the perennials will soon head into winter dormancy, but fall planting often gives these perennials a head start over their spring-planted counterparts.
In spring, the fall-planted perennials should be raring to grow, larger and more robust. You can expect a good show.
Fall planting also applies to perennials you want to dig up and move to a new spot and to divisions (strong, rooted pieces of overgrown plants).
When getting ready for fall planting, make sure you do the following:
Buy good, strong plants. These plants have the best chance to establish themselves in your garden.
Mulch a little at planting time, about 1/2 to 1 inch, to hold in soil moisture and warmth; mulch even more as winter arrives, another 2 or 3 inches after the ground freezes, to protect the plants during the cold months.
Cut back the top growth, just to further urge the plant to concentrate on root growth.
Here are some things to avoid during fall planting:
Fertilizing: Fertilizing inspires a fresh spurt of young shoots and leaves, which are vulnerable to cold damage. You want perennials to enter their winter dormancy.
Planting late-bloomers: Late bloomers (like asters, mums, black-eyed Susan, and perennial ornamental grasses) are better planted in spring.