Tips for Fall Planting and Transplanting

When the hot summer weather breaks and cool air returns, it’s the perfect time to plant or transplant just about anything, especially spring- and summer-flowering perennials.

At the beginning of spring, gardeners are inspired to plant anything and everything. But how many times have your planting plans been foiled by cold, lingering springs or early heatwaves? Slow or stunted growth may be the result, or a plant stressed to the point of dropping flowers or foliage.

Why fall is the best time to plant or transplant

In the fall, weather and soil temperatures are more predictable than they are in spring. Daytime air temperatures have moderated, nights are cool, and the days are shorter. These conditions create a much less stressful environment for newly planted or transplanted trees and shrubs when compared to spring.

Another bonus in fall is that the soil is warmer. This encourages substantial root growth quickly and a solid anchor to get the plant through its first winter. A well-established root system from the outset ensures a powerful display of flowers and growth the following spring and summer and a healthier plant in the long term.

In the fall, soils hold onto heat longer even as above-ground temperatures are dropping, which is ideal for new root structures to grow. The root systems need time to establish new micro or feeder roots which helps the transplant to acclimate, then gradually go into dormancy as colder winter temperatures arrive. Fall transplants have better root structure and more time to acclimate to the local environment.

University of Illinois Extension

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When to plant perennials in fall

Timing is important when planting in the fall, so that shrubs and trees have time to develop a strong root system to anchor them and guard against frost heaving. Roots grow until soil temps reach about 40 degrees and typically at the start of fall the soil is considerably warmer. Try and plant about 6 weeks before your first frost date, about the same time you plant flower bulbs.

[su_note note_color=”#ffffc2″ radius=”10″]What About Frost? Frost will stop the growth of the plant above ground, but it will not kill the plant. The roots will continue to grow in the fall until the soil freezes solid (if it does). See our post about when to expect your first frost.[/su_note]

Tips for planting perennials in fall

Spring- and summer-flowering perennials will establish best when planted in fall.

• If you plant a fall-blooming variety, remove the flowers after planting to encourage root growth instead of blooming or seeds.
• Root wash your perennials before planting to ensure their survival and long-term health. See our post on root washing.
• When dividing perennials and replanting the divisions, spring and early-summer bloomers will perform best. As a rule of thumb, always divide perennials in the opposite season from which they bloom: If a plant flowers in early summer and spring, divide in fall; for late summer and fall bloomers, divide in spring.
• Deeply and thoroughly water the root zones of new plantings once a week. Aim to give them 1″ of water each time in the absence of rainfall. Stop watering after the first hard freeze.
• Add 2-3″ of mulch around the root zone to conserve moisture and insulate the soil from temperature swings. Mulch doesn’t necessarily mean wood chips – you can also use straw, leaf litter, compost, or similar organic materials. Wood chips can be added later as a winter mulch right before your first freeze. Remember to remove it in early spring to warm the soil faster.
• Go easy on the fertilizer. Perennials planted in fall need little in the way of care aside from proper watering. Adding no fertilizer is recommended by the University of Illinois, as nitrogen added right after planting will encourage too much top growth when you want exactly the opposite to happen: robust root growth. New top growth also may not harden off before winter freezes that may damage the new growth.