6 Last-Minute Perennials to Plant Before the First Frost According to a Gardening Expert

Until the first frost of fall hits your garden, you can still plant perennial flowers and foliage for brilliant color the following year. But hurry. Your plants need time to get established.

When Is the First Frost?

These days, with climate change, potentially longer seasons of warm temperatures give us more time to plant before a frost or freeze. A freeze occurs when the air temperature drops to 32 degrees F. or lower, which kills tender annuals and can damage other plants. Frost is said to occur when the air temperatures range from 33 to 36 degrees F. and ice crystals form on plants, lawns and other surfaces.

In regions with mild winters, gardeners can plant perennials year-round, although spring and fall are considered the best times. In other parts of the country, there's a window of opportunity between fall and the onset of cold winter weather when you can plant them. But don't hesitate. You can't work the soil if it's frozen, and perennials need enough time to establish good root systems.

Before you begin, find out when the first frost is expected in your area. Ideally, you'll plant perennials six weeks before that date, or at least four weeks before. Then grab a shovel or trowel, browse our list of favorites and dig in.

Tips for Planting Perennials Before Frost

• What to do if you don't have six weeks until frost: If you don't have at least a month before frost, and your perennials are in plastic pots, here's an option; water the pots thoroughly, let them drain, take the perennials out of the pots and plant them in the ground. Then, mulch them heavily. This avoids watering the ground just before a frost, which can lead to frost heave. Frost heave happens when water in the ground freezes, expands, and pushes up, even to the point of pushing plants out of the ground. Frost heave can occur in cycles as the ground thaws and refreezes again and again.
• Or plant the potted perennials in the ground: According to experts at the New York Botanical Garden, you can also opt to water perennials growing in plastic pots, let them drain and then plant the pots directly in the ground. Leave the rims slightly above or at the soil line. This can also help avoid damage from frost heave. After the potted plants are in the ground, mulch heavily around them. When all danger of frost has passed next spring, lift the pots, remove the perennials and replant them in the ground. Recycle the pots, water the plants and apply new mulch.
• What to know about yellowing leaves: Be aware that the perennials you plant or grow in fall may have yellowing or dropping leaves. In some cases, those can be signs of distress, but if your plant seems healthy otherwise, they're probably just normal signs that your perennials are going into a period of dormancy.
• Look for new growth in the spring: Don't be too quick to pull up perennials that appear dead next spring. Their roots can survive even if above-ground growth perishes. Wait to see if they put out new growth when the weather warms up.

Coneflowers

Coneflowers (Echinacea) are much-loved perennials available in a variety of colors, with boast daisy-like blooms that attract pollinators like bees and butterflies. Let the seedheads remain on the stems after the flowers finish, and hungry songbirds will often visit. Coneflowers need part sun to sun and bloom from early to late summer. Best of all, they're happy in average to poor soils and are drought tolerant once they're established. They're hardy in USDA Gardening Zones 4 to 9. This is Sombrero Lemon Yellow.

Russian Sage

For hot, dry areas where other plants struggle, Russian sage (Perovskia atriplicifolia) can thrive. Hummingbirds will visit the long-lasting flowers, which open from spring into fall and add a hard-to-find shade of blue to the garden; some have flowers that lean toward lavender-purple. The foliage is grayish-green to silver. Hardy in Zones 4 to 9, the plants reach 28 to 32 inches tall and prefer sun. While they need soil that drains easily, they'll grow in fertile, poor or average soils. The variety pictured here is 'Denim 'n Lace'.

Hosta

Think all hostas are plain green? Think again. These perennials come in every color of green you can image, and in shades of blue, cream, white and yellow. Many are variegated. They range in size from miniatures to giants that reach three feet or more tall and up to six feet in width. While hostas aren't grown primarily, for their flowers, which are typically small and insignificant, the blooms do attract hummingbirds. Most hostas are hardy in Zones 3 to 9 and are easy to grow. Depending on the variety, give them shade, dappled sunlight or a few hours of cool morning sun; hot, intense sun will burn the foliage. They do best in rich, fertile soil.

Lenten Rose

Also known as winter roses, Lenten roses (Hellebores) are late winter to early spring bloomers, hardy in Zones 5 to 9. Some varieties are speckled or bicolored and you can find many colors, including white, pink, red, purple, yellow and green. Mature plants form clumps with nodding, cup-shaped flowers and need shade to light, so avoid areas that get bright, winter sun. Give them a spot with moist, well-drained soil. Deer tend to leave them alone--although when fall and winter food sources are scarce, and deer are hungry, they'll eat almost anything. Shown here: 'Confetti Cake' Lenten rose.

Coral Bells

Like hostas, coral bells (Heucheras) are grown more for their colorful foliage than their flowers. Their ruffled, smooth, patterned or frilly leaves come in stunning shades that range from green to purple, purple-black, peach, yellow and more. Because coral bells can hold their leaves year-round, they've considered evergreen or semi-evergreen plants, but the foliage may die in cold winter climates or become tattered-looking by fall and winter. It's a good ideal to leave the foliage in place for winter protection, and wait until new spring growth emerges before removing it. Depending on the variety, coral bells like partial shade to full sun; give them rich soil that drains easily. Some have showy flowers, while others have unremarkable blooms. The plants are hardy in Zones 4 to 9.

Astilbe

'Fanal’ astilbe, shown here, unfurls its fluffy, vibrant red flowers in late spring to early summer. The leaves emerge bronze-green and eventually become a darker green with red tints. This deer- and rabbit-resistant perennial can reach 20 inches tall by 18 to 20 inches wide. Dwarf astilbe varieties can grow just six to 10 inches tall while others can top out at six feet tall, measuring to the tip of the flower spikes. Look for the plume-like flowers in white or shades of pink, lavender, violet and red. Many varieties can take full sun in cool, northern gardens, but elsewhere, they grow best partial to full shade. Give them well-drained soil; they're hardy in Zones 3 to 8. Most will flower in the second year after planting.