What To Plant - And What Not To Plant - In The Fall
What To Plant - And What Not To Plant - In The Fall
By Natalie Carmolli, Proven Winners® ColorChoice®
Photographs courtesy of Proven Winners® ColorChoice®
Fall is a great time to plant most woody ornamentals. As you start to feel a break from the consistent heat of summer, take a look around your garden. You may see flowering shrubs like roses setting a round of late-summer buds, or your panicle hydrangea blooms starting to pink up. The colors of autumn will soon emerge in deciduous shrubs and trees, creating a whole new garden palette.
Changes are also occurring underground. Cooler days and nights create an ideal, stress-free environment for root growth, one where newly planted woody ornamentals and perennials can quickly establish. Root growth is stimulated when outside temperatures sit between 72 and 65 degrees Fahrenheit (22.2-18.3 C), but they can continue to develop as long as the soil temperature is above 40 degrees.
When temperatures start to dip below freezing, deciduous plants lose their leaves and the root system stops most of its function – the plant has gone dormant.
Eventually, warm spring temperatures arrive again, plants wake up and put their energy into growth above the soil. Those news roots that grew in the fall begin their job of moving water through the new plant tissues. If you took the time to plant new shrubs or perennials before winter, you’re about to watch them as they grow and mature throughout their first season in your garden – and because you planted in fall, they’ve got a great head start!
Planting in Fall
Shrubs like hydrangeas, roses, rose of Sharon, and weigela are ideal for fall planting. The technique is similar to what you would do in spring. Simply dig a hole a couple of sizes larger than the container, loosen the root ball, place your shrub in the hole with the plant's crown just above the soil line, and backfill with the existing soil. There is no need to amend the soil; just mix the medium that came in the container with the native soil. Once your shrub is in place, water well and apply a 2-3" layer of shredded bark mulch.
What Not to Plant in Fall
Not all woody ornamentals enjoy being planted late in the season. Bareroot plants and broadleaf evergreens, like holly and boxwood, are better planted in spring. Fall-planted broadleaf evergreens can fail in winter due to water stress from transpiration. What’s transpiration?
Transpiration is when plants release water vapor, or transpire, from their foliage. All plants do this in the summer. But since evergreens hold on to their leaves all year, they also transpire during the winter. From spring through fall, plants can replace the moisture that transpires from their leaves by drawing water up through the roots. But when the ground is frozen, plants can't access that moisture.
Conditions like windy, dry winter weather or days when the weather warms but the ground is still frozen pull moisture from foliage, leaving broadleaf evergreens vulnerable to desiccation – the foliage dries up completely and dies. Sometimes the entire shrub can die from desiccation. Shrubs in full sun or exposed, windy locations are most susceptible to winter desiccation.
If you must plant a broadleaf evergreen in fall, give it the best start possible. If it’s planted in an exposed location, consider using an anti-desiccation spray at the beginning of winter to reduce stress from transpiration. Then apply a 2-3" layer of mulch and make sure you give your new plant plenty of water until the ground freezes to keep roots well-hydrated for winter. Additional watering up until the ground freezes may be required, particularly if the fall is unusually dry.
Fertilization In The Fall?
While we encourage fertilization once in early spring and again about a month later, you should not fertilize your woody ornamentals after July. Fertilization promotes new growth, which won't have time to harden off before your plant needs to go dormant for the winter.
Selecting For Fall Color
Autumn is a great time to select trees and shrubs for leaf color. It's the season when plants reveal their fall colors, so you can choose ones that add vibrancy to your garden or landscape. A visit to your local garden center will reveal shrubs and trees you may have passed over in the summer before their foliage really started to shine.
These shrubs are ideally suited to fall planting, with blazing foliage that is a brilliant bonus.
This native, pollinator-friendly plant provides full-season interest with white spring flowers, purple summer berries, and bright orange fall foliage. It's also a rugged problem solver and thrives in difficult growing conditions. Consider Low Scape Mound® (1-2’ tall/wide), Ground Hug® (8-14” T/3’ W), or the new Low Scape Snowfire™ (3-4’ T/W) for an extra strong spring flower show. USDA Zones 3-9.
Diervilla (bush honeysuckle)
Also native, Diervilla features tubed, yellow spring flowers that pollinators love, plus they tolerate dry shade conditions. The foliage comes in a wide array of colors and the long, straight stems are perfect to use in cut flower arrangements. Proven Winners® ColorChoice® has four compact cultivars of this native species in four fabulous foliage colors: the newest is the 2-3’ chartreuse-green Kodiak Fresh™, but for impressive fall color choose the 3-4’ Kodiak® Orange; planted in partial sun the foliage will turn blazing red at the end of the season. USDA zones 3-8.
Fothergilla has long been appreciated for its spectacular autumn color as well as its fragrant white flowers in spring that provide sustenance to pollinators as they wake up or migrate back. Legend of the Fall® Fothergilla sets a new standard for the species with brilliant, glowing hues of orange, yellow, and red. It sports a neat and tidy 4-5’ habit which makes it easy to work into your landscape or garden. If that is still too big, the 2-3’ Legend of the Small® produces an abundance of bottle brush-like white flowers in spring, and boasts an appealing, well-branched mounded habit. Its small bluish-green leaves turn an attractive blend of yellow, orange, and red in autumn. Fall color will be most vivid for both when planted in spots that get at least some sun each day. USDA zones 5-9.
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By Heirloom Roses
Photographs courtesy of Heirloom Roses
In many areas of the country this is an excellent time to prune roses. Although rose pruning may seems daunting, it’s not hard to learn and the results are well worth the effort. For an informative article on rose pruning, click here .
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