Planting annuals in spring

Zone 7 Annual Flowers – Selecting Zone 7 Annuals For The Garden

Who can resist spring annuals. They are often the first flowering plants in the garden. Time of last frost and hardiness are important aspects when choosing zone 7 annual flowers. Once those details are sorted, it’s time for fun. Blending colors and textures can make container gardens and flower beds especially appealing with zone 7 annuals.

Planting Annuals in Zone 7

Annual plants add immediate punch to the flower garden. There are annuals for sun or partial sun locations. Most popular annuals for zone 7 are tried and true selections with many cultivars and colors. Some are more commonly grown for their foliage and are perfect foils for setting off color displays. With good care, annuals can brighten the garden from spring until the first frost.

Local garden centers will carry the most popular annuals for zone 7. This makes it easy to find hardy classics such as petuniasand impatiens. You may choose to sow seed or purchase blooming plants. Sowing seeds can be done outside after all danger of frost has passed but the appearance of flowers will take quite some time.

A quicker method is to sow in flats indoors 6 to 8 weeks before the last expected frost date. This gives you a jump start on popular annuals for zone 7. Most seeds will germinate readily in well-draining seed starter mix where temperatures are at least 65 degrees Fahrenheit (18 C.).

Choosing Zone 7 Annuals

Plant selection will depend on how large you need plants to become and if you have a color scheme. Other things to consider will be site conditions. The amount of light per day for a full sun variety will be 6 to 8 hours.

Also, there are plants that thrive in hot, dry and nearly drought-like conditions, and those that need plenty of water. There are also hardy, half hardy, or tender varieties.

  • Hardy annuals can usually tolerate cold temperatures and freezing. They are planted early in spring or even in fall. Pansies and ornamental kale are examples of hardy annuals.
  • Half hardy zone 7annual flowers, like dianthus or alyssum, can handle a light frost.
  • Tender annuals might be zinnia and impatiens. These types of plants do not tolerate cold or frost and must go in ground after all danger is passed.

Annuals for hot, dry locations

  • Black eyed susan
  • Cosmos
  • Coreopsis
  • Lantana
  • Salvia
  • Spider flower
  • Strawflower
  • Globe amaranth

Annuals for cooler, sunny areas of the landscape

  • Marigold
  • Petunia
  • Portulaca
  • Sweet potato vine
  • Geranium
  • Dahlia
  • Cypress vine

Annuals for partial shade

  • Monkey flower
  • Forget me not
  • Impatiens
  • Begonia
  • Coleus
  • Pansy
  • Lobelia

Annuals for cool season

  • Snapdragon
  • Dianthus
  • Pansy
  • Ornamental kale

Remember, when planting annuals in zone 7, all selections will require good fertile soil and average water while establishing. Fertilizing and deadheadingwill enhance the appearance of the plants. A slow release flower food is perfect for feeding the plants throughout the season. This will encourage more blooms and aid in the overall health of the plant.

Planting Annuals

The best time to plant annuals depends on the specific plant and your climate. Annuals are designated as “cool-season” or “warm-season,” based on their hardiness and ability to grow in cool soils.

Cool-Season Annuals

Cool-season annuals, such as pansy (Viola), primrose (Primula), and calendula, grow best in the cool soils and mild temperatures of spring and fall. Most withstand fairly heavy frosts. When the weather turns hot, they set seed and deteriorate. If you live in a cold-winter area (Zones 1–6, 32–45), plant these annuals in very early spring, as soon as the soil can be worked. To bloom vigorously, they must develop roots and foliage during cool weather.

In mild-winter regions (Zones 7–31), many cool-season annuals can be planted in fall for bloom in winter and early spring; or plant them in late winter or very early spring for spring flowers.

Warm-Season Annuals

Warm-season annuals include marigold (Tagetes), zinnia and impatiens. These plants grow and flower best in the warm months of late spring, summer, and early fall; they’re cold tender and may perish in a late frost if planted too early in spring. In cold-winter climates, set out warm-season annuals after the danger of frost has passed. In warm-winter areas, plant them in midspring.

Careful soil preparation will help get your annuals off to a good start and keep them growing well all season. Dig out any weeds on the site and add a 3-inch layer of compost, well-rotted manure, or other organic amendment. It’s also a good idea to add a complete fertilizer; follow the package directions for amounts. Dig or till amendments and fertilizer into the soil, then rake the bed smooth.

You can start annuals from seed sown in pots or directly in the garden, or you can buy started plants at a nursery. Nursery plants may be sold in flats, cell-packs, peat pots, or gallon containers; see Planting basics for tips and instructions. For best results, choose relatively small plants with healthy foliage. Plants with yellowing leaves and those that are leggy, rootbound, or too big for their pots will establish only slowly in the garden, and they’ll usually bloom poorly.

After planting, water the bed thoroughly. Young seedlings or transplants may need water once a day in warm weather, but as they become established, you can gradually cut back. Apply a 2- to 4-inch layer of mulch (such as compost, ground bark, or pine needles) to conserve moisture and help prevent weeds from becoming established.

Mixing a complete fertilizer into the soil before planting will generally supply your annuals with nutrients sufficient for at least half the growing season. In cold-winter areas, an additional feeding after bloom begins will carry the plants through their season. Where winters are warmer and the growing season correspondingly longer, apply fertilizer again in late summer.

Winter Annuals

In November while cold-winter gardeners are busy tilling beds, protecting plants, and generally getting ready for the onset of cold temperatures, gardeners in the southeastern coastal plain, southwestern deserts, and West Coast (USDA Hardiness Zones 8 through 10) are busy planting, among other things, flowering annuals. If you’re a gardener in Tampa, Gainesville, New Orleans, Houston, Phoenix, Los Angeles, San Francisco, Seattle, or any other mild-winter area, late fall is the perfect time to set out transplants for blooming right through the dark months of winter. You’ll find a host of choices, such as ornamental cabbages and kales, pansies, snapdragons, that can be planted now.

Choosing the right annuals and the correct varieties of them for your area is key to creating a colorful planter, window box, or garden bed. Growing them requires taking into account low light levels, cooler soil temperatures, and the occasional extreme weather of systems such as El Nino and La Nina.

Although many annuals, such as calendulas, geraniums, and sweet peas, can withstand a light frost, these tend to flower sporadically in all but the frost-free areas of the South and West. The key to long bloom is finding annuals that continue to flower during the short, cold days of December, January, and February. These are what I call true winter annuals. Based on my talks with gardening experts from Tampa to Seattle, I’ve selected the best varieties of eight of the most widely available and popular annuals. Unless otherwise noted, all of these will perform well throughout mild-winter areas.

Not Just Pansies: Hardy Winter Annuals

Snapdragon (Antirrhinum majus). Varieties come in heights from dwarf ‘Bells Mix’ (8 to 10 inches), semidwarf ‘Sonnet Mix’ (15 to 20 inches), to tall ‘Liberty Mix’ (2 to 3 feet). ‘Black Prince’ (18 inches tall) performed well in University of Georgia trials. Plants are hardy into the 20s and will flower throughout the winter as long as day length exceeds 10 hours. An added value is snapdragons’ fragrance. All taller varieties benefit from being pinched back at planting to force more flower stalks to form.

Ornamental cabbage and kale (Brassica oleracea). Although these are not flowering plants, it would be difficult to write about winter annuals without including them for their unique leaf shapes and colors. The colors intensify in cold weather, providing accents in the garden or in large containers, and they complement flowering annuals such as pansies and violas. They grow to about 12 inches wide and high, are hardy into the 20° Fs, and can grow in partial shade. ‘Peacock Mix’ flowering kale and ‘Tokyo Mix’ flowering cabbage are particularly attractive. Other appealing foliage plants that are becoming more available as winter transplants include ‘Red Bor’ and ‘Red Russian’ kale, ‘Red Giant’ mustard, and ‘Bright Lights’ Swiss chard.

Cyclamen (C. persicum). Florist’s cyclamen is usually thought of as a holiday houseplant, not an outdoor winter annual. However, it can take light frost and will continue flowering as long as temperatures stay above 45° F. They add stunning crimson, purple, red, salmon, or white to a bed or container. While they’re not commonly planted in the Southeast, they grow well in southern Texas, the low deserts of the Southwest, and coastal California. The 10- to 12-inch-tall plants combine well with other annuals, or can be mass-planted for dramatic effect. The Miracle and Laser series have the bonus of being fragrant. Cyclamen perform best when planted in a partly shaded area with good water drainage and air circulation.

Chinese pink (Dianthus chinensis). Chinese pink is generally underused as a winter annual, but newer hybrids such as the Diamond and Ideal series are more cold- and heat-tolerant than older varieties and will flower all winter from Georgia to California. One-inch-diameter flowers come in pink, red, white, and bicolors; petals can be deeply fringed or smooth. Some have a spicy fragrance. Many varieties grow to only 12 inches tall.

Stock (Matthiola incana). Newer varieties such as the Vintage series have a strong clovelike fragrance on the 18-inch-tall flower spikes of lavender, lilac, red, and white that have an extended bloom time. The grey-green foliage adds another value. For best flowering, provide good drainage and full sun, and choose transplants with flower buds already set. If plants are set out in cool soil before flower buds have formed, they may not flower.

Primrose (Primula). Of all the hundreds of species, selections, and hybrids, only a few are used successfully as winter annuals, mostly in coastal, central, and southern California and low-desert areas of the Southwest. Colors range from white to red and blue. Polyanthus (P. polyanthus) and English (P. acaulis) primroses perform well outdoors all winter. P. p. ‘Crescendo Mix’ and P. a. ‘Supreme Mix’ are widely adapted, with fragrance as an added benefit. In frost-free areas of the Southwest, California, and south Texas, consider the tender P. obconica ‘Libre’, which is free of primin–a compound in many primrose leaves that causes mild skin irritation. If you want to try growing primulas in the Southeast, a good choice is P. a. ‘Pageant Mix’, which performed well in trials at the University of Georgia.

Viola (V. cornuta). This pansy cousin is equally hardy and flowers more readily than pansies, although the flowers are smaller. The trend in violas, as with pansies, is toward single flower colors from white to red and away from the faced varieties such as V. tricolor ‘Johnny Jump Ups’. Violas have great resistance to adverse weather and are very hardy. They even overwinter under the snow in my Vermont garden, flowering each spring. Some of the best varieties for uniform plant and flower size and consistent flowering habit are in the Penny and Sorbet series, such as ‘Penny Blue’, ‘Penny Yellow’, ‘Sorbet Blueberry Cream’, and ‘Sorbet Lemon Chiffon’.

Pansy (V. wittrockiana). This is the king of winter annuals. Plants will continue to flower with temperatures into the 20° Fs and can survive into the teens. In rainy-winter areas such as the Pacific Northwest and the northern California coast, light-colored varieties seem to stand up better than dark-colored ones. Light blues and yellows such as ‘Crystal Bowl Primrose’ and ‘Universal Plus Yellow’ tend to rebloom faster, and their smaller flowers stand upright better, especially in the rain, than the giant varieties. However, in warmer areas such as southern California and the desert Southwest, larger-flowered kinds such as the Maxim Supreme series are best because warm weather tends to shrink flower size. Like violas, the gardening trend in pansy varieties is away from the faced kinds such as ‘Majestic Giant’ and toward solid-colored types such as ‘Crystal Bowl’. Trials highlight these series: Accord, Baby Bingo, Crystal Bowl, and Universal Plus.

Even though the plants described above offer the most consistent winter color, you need not limit yourself just to these. In many places, even though cool-season annuals may not bloom throughout the winter or survive a hard freeze, they are worth trying because they make excellent combinations in containers and beds with the true winter annuals.

Some good choices to try are calendula, nemesia, petunia, sweet alyssum, and verbena. These tend to grow best in warmer areas (zones 9 and 10), but they may provide some late-fall or early-spring color in cooler areas if the weather isn’t too severe. Also, plants such as dusty miller and ornamental grasses provide attractive foliage to complement the flowers.

Winter Culture

Growing annuals in winter is a bit different from growing them in other seasons. Light levels are lower and plant growth slower. Plants such as pansies that normally would shun the bright sun are more tolerant of full sun. Although temperatures may rarely drop to freezing, the cooler air and generally more frequent rains tend to keep the soil moist longer.

In cool, moist soils you’ll need to adjust your fertilizing schedule and take steps to prevent rot diseases. In containers, use a light soilless mix. In gardens, improve drainage with raised beds, especially if you live in a wet area with heavy soil. Cold, wet roots are a sure way to rot plantings. Remove summer mulches such as bark; don’t till them into the soil. Incorporating high-carbon mulches will create a nitrogen deficiency in the plants.

At the nursery, choose plants (November is too late to sow seeds) that are already flowering or have obvious buds. Annuals that haven’t set flowers by November are not likely to flower well all winter. Set out various combinations of plants as soon as you can, remembering that plants will not grow fast in winter so spacing can be a bit closer than normal. Fertilize sparingly with a fertilizer containing a nitrate form of nitrogen, such as calcium nitrate, during the season. Nitrogen fertilizers containing ammonium can cause leggy growth during brief warm spells, but when the soil cools below 45? F, the nitrogen becomes unavailable to plants. Reapply mulches in drier winter areas such as the desert Southwest. Now just sit back and enjoy a winter season of beautiful flowers.

Charlie Nardozzi is a senior horticulturist at National Gardening.

Photography by National Gardening Association and Suzanne DeJohn.

Winter Flowers for the South

For many, winter marks the end of the growing season. For others, winter doesn’t mean it’s time to hang up the garden tools. Gardeners in the South and Southern California can choose from a wealth of plants—annuals and perennials—that prefer cooler temperatures and offer beautiful winter flowers. Take a look at the plants that these regions are lucky enough to grow in the winter.

Winter-Flowering Annuals

It’s important to understand that annuals are just what their name implies: Plants that grow, set seed, and die within a year. Although some plants grown in northern gardens are treated as annuals, many are truly tender perennials that can’t survive winter cold. These annuals add color to a winter landscape.

Related: Complement Winter Flowers With Evergreens

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Sweet Alyssum

With 12-inch mounds of tiny, fragrant flowers in pink, white, or lavender, sweet alyssum (Lobularia maritima) is a favorite cool-growing annual. Use it to edge beds and paths, or tuck it into small, dark spaces. Grow it in full sun to part shade in well-drained soil. Although it tolerates some dry conditions, for best performance, keep it watered. Expect alyssum to go dormant during hot weather. This plant grows best in Zones 9-11.

Calendula

The bright yellow, cream, or orange blooms of calendula (Calendula officinalis) light up a garden. If the plant is grown without chemicals, the peppery petals may be used as an edible garnish or chopped into cream cheese or dips. Grow calendula in full sun in Zones 2-11.

Honeywort

Native to the Mediterranean, honeywort (Cerinthe major purpurascens) is an unusual and underused plant. Plant it in full sun or light shade. The plants, with silvery blue-green leaves and blue-purple flowers, can reach 2 to 3 feet tall and wide. It self-sows but dies out during hot weather. For best results, grow honeywort in Zones 9-10.

Related: Silver-Leaf Plants for Your Garden

Sweet Pea

Grow annual sweet peas (Lathyrus odoratus) on trellises or obelisks where the tendrils of this vine, native to Italy, can climb up to 6 feet. Enjoy the clusters of fragrant, ruffled blossoms as cut flowers. Start sweet peas from seed by soaking them in water for 48 hours, then plant in full sun. Sweet pea grows best in Zones 6-9.

Winter-Flowering Perennials

Although many perennials grow best in stronger light and warmer temperatures, these provide color in a winter garden.

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Pansies and Violets

Pansies (Viola x wittrockiana) and violets ((Viola) species) are the go-to standbys for cool-weather blooms. Their engaging “faces” top petals that come in bold or pastel colors. Plant pansies 4 to 6 inches apart in rich, well-drained moist soil in sun or light shade. Water and fertilize them regularly. Remove spent flowers to promote repeat blooms. Although they’re perennials, pansies and violets are short-lived because they can’t tolerate heat. Some pansy varieties are more heat-tolerant than others; violets take more heat and may reseed. Both plants grow hardy in Zones 3-9.

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Pinks

Pinks (Dianthus species and hybrids) are named not for their color—although many are pink—but because the edges of their serrated leaves look like someone cut them out using pinking shears. The blooms often smell like an aromatic spice, such as nutmeg, ginger, or cinnamon. You can find many types of these short-lived perennials, including China pinks (Dianthus chinensis), that grow in 6- to 12-inch mounds of grasslike blue-green foliage. Sweet William (D. barbatus) grows taller, up to 2 feet. Cheddar pinks (Dianthus gratianopolitanus) and maiden pinks (Dianthus deltoides) are also part of the family. Grow them in full to part sun. Zone hardiness varies by species.

Winter Jasmine

You’ll love the early burst of color from winter jasmine (Jasminum nudiflorum), a fast-growing evergreen shrub for full sun or light shade that offers lots of creamy-yellow flowers. It can reach 10 feet tall and wide and is hardy in Zones 6-9.

Winter Honeysuckle

Offering one of winter’s best scents, winter honeysuckle (Lonicera fragrantissima) shows off clusters of creamy-white flowers in late winter and early spring. It can grow 10 feet tall and wide and is hardy in Zones 5-8.

  • By Deb Wiley

Most of the plants that you are going to have in your garden, whether it is indoors or outdoors, are going to bloom mostly during the spring and the summer months of the year.

I love to see blooms in my garden at all times of the year, so I have been looking for annuals that will bloom in the fall to plant around my garden.

So far, I have found a few that will look amazing in the fall, but the options are a bit limited. So, to help out others who are looking for annuals to bloom during the fall months, I created this list of 15 different annuals that can help to expand the time of the year when you see blooms.

1. Snapdragons

Snapdragons are lovely plants that produce trumpet-shaped bloom in the summer that will extend through the fall of the year. These plants can grow to be up to 8 feet tall, so they can be trained to climb in your garden. They tend to grow in zone nine and above with ease.

2. Pansies

Pansies are a plant that loves the cool weather, so it makes perfect sense that the plant would be one of the best fall blooming annuals to have in your garden. If you are growing this plant as an annual, it will need to be in zone four or above. This plant requires partial shade and well-drained soil to thrive. See the different varieties of Pansies here

3. Dianthus

This is a plant that tends to stop blooming during the hot summer months, so you will be able to see the blooms during the fall when it is cooler. This is a plant that grows in zones three to nine. Dianthus flowers, which can also be known as pinks, need well-drained soil and about six hours of sun a day.

4. Croton

Crotons are plants that not only bloom during the fall, but the leaves are also the bright colors of fall. These plants can be grown as annuals in zones nine to 11, and they will continue to bloom until the first frost of the year hits. They also like well-drained soil and about six hours of sunlight a day.

5. Ornamental Peppers

Most peppers do not seem to like the cold weather very much, but these ornamental ones bloom from the late summer month into the fall, which means that they are a fall-blooming annual. With full sun and well-drained soil, they should grow well in any garden in zones nine to 11.

6. Flowering Kale

This is a type of ornamental kale that is seen growing in zones two to 11. It tends to grow best in full sun and well-drained soil, but the plant will hold up to the cooler temperatures of the fall. In fact, the plant can be seen in the winter in locations with milder temperatures.

7. Ornamental Cabbage

Ornamental cabbage is not a type of plant that is edible, but it is a hardy flowering plant that will be quite colorful in the fall. These plants are green and purple, and they can be found in nearly any zone because they can tolerate cooler temperatures. They also grow best with full sun and well-drained soil.

8. Sweet Alyssum

This small plant is only about 6 inches tall, which makes it a great plant for edging along a walkway. It is a plant that loves cooler temperatures, and with full sun, it will grow well in zones seven through 11. This plant’s sweet smell also attracts butterflies and bees to your garden.

9. Begonias

Begonias come in fall colors with blooms that are orange, white, pink, purple, and red. They grow best in zones eight to 10 as annuals, but they can grow in other zones as perennials. In addition, they tend to need well-drained soil and full to partial sun to thrive.

10. Petunias

Petunias are plants that begin blooming in the summer of the year, and in the right area, they will continue to produce flowers throughout the fall as well. The blooms will vary in color quite a bit, but the plant only grows to be a foot tall in zones eight to 11.

11. Nasturtium

Another flower that comes in a lot of fall-like colors is the nasturtium. It grows in zones nine through 11, and it can be seen blooming during the late summer and the fall of the year. This is a plant that will grow best in full sun and well-drained soil.

12. Celosia

This is a great fall plant that will create blooms that are red, orange, yellow, pink, purple, and white. It can grow to be from 6 inches to up to 3 feet tall. In zones two through 11, this is a plant that can handle cooler temperatures, but it will thrive in full to partial shade.

13. Calendula

This plant has bright yellow blooms that will make you feel like fall is all around. In addition, this is a plant that prefers the cool temperatures of spring and fall, so this is the time when the blooms will be seen. Growing in zones eight and up, this is a plant that prefers full sun and well-drained soil.

14. Chrysanthemum

Chrysanthemums, or mums as they are sometimes called, are fall-blooming plants that have flowers that are red, orange, yellow, and peach. They can be a few inches tall or a few feet, depending on the type. It is a plant that requires full sun and well-drained soil to grow, and it will do best in zones five to 10. Because of the plants’ shallow roots, it will need a bit more water than most plants.

15. Aster

Asters can grow as either annuals or perennials, but it will be seen growing best in zones three to eight. These blooms are purple, pink, and blue, which are not a traditional fall plant’s coloration, but it can help brighten up your garden and bring butterflies and bees to your outdoor space. It will grow best with full sun and well-drained soil.

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Your ultimate flower calendar: The best time of year to plant all your garden favourites

Not sure what to plant when? Here’s our guide to give you colour in every season.

Winter

Early winter is a great time for planting bare-root roses and other dormant shrubs before the ground becomes too hard or waterlogged. They should give you plenty of colour in the warmer months.

Meanwhile, winter is the peak season for brightly berried hollies, delicate-looking hellebores, shrubby honeysuckles, fragrant yellow evergreen mahonias and wintersweet, whose pale yellow flowers hang from bare stems from December to March and which gives the more popular witch hazel a run for its money.

For scent, look no further than Viburnum x bodnantense and, if you’re after unusual berries, check out the purple fruits of Callicarpa bodinieri var. giraldii ‘Profusion’, which can last until December.

In January, see the first of the bulbs emerge, including snowdrops, crocuses and early daffodils such as Narcissus ‘February Gold’.

Unlike other spring-flowering bulbs, tulips can be delayed from planting until November and December, if the ground isn’t too hard or waterlogged.

Winter pansies and violas which gave some colour in tubs and troughs in the autumn may sulk during the depths of winter, but they’ll spring back to life when the days become longer in spring.

Late winter is also a great time to sow seed in a heated greenhouse or on a windowsill, such as tuberous begonias, busy Lizzies and sweet peas.

Spring

Beautiful summer-flowering bulbs such as dahlias, cannas and lilies can be planted in spring.

Plant lilies in early spring before the bulbs dry out.

Tender bulbs such as dahlias, cannas and begonias are not frost-hardy so start them off in pots indoors in the spring and don’t put them out until all danger of frost has passed. Most bulbs prefer a sunny position, or will do well in light shade.

Spring is the time to enjoy the bulbs you planted in the autumn, whether it be masses of bright yellow daffodils, heavily-scented hyacinths, frilly tulips or lollypop alliums.

Other spring-flowering beauties include dicentra (bleeding heart), whose ferny foliage covers fading snowdrops in spring and whose pink flowers provide a pretty display from mid-spring.

Evergreen perennial wallflowers, crown imperials and aquilegia vulgaris are other colourful stars of spring, while hardy perennials and shrubs can also be planted at this time of year, as the ground becomes warmer and easier to work.

Spring is also the time to plant colourful primulas, heathers and hybrid primroses to perk up your patio pots.

If you can take pots under cover at night, you can plant up summer containers and hanging baskets in late spring.

It’s also a perfect time for planting perennials including lupins, delphiniums, foxgloves and peonies, keep them well watered and wait for the summer colour to arrive.

Summer

Early summer is arguably the most colourful time in the garden, when you can plant up all manner of annuals – either grown from seed or available in garden centres – in your containers and troughs.

As soon as all risk of frost has passed, pelargoniums, lobelia, stocks, petunias, verbena, fuchsias and begonias can go outside.

If you have cover, you can give them a head start by planting up pots in spring, but only if you have somewhere to protect them.

Summer perennials should be coming into flower – lupins, delphiniums, roses and climbers including large-flowered clematis are in their element and lavender flowers are producing their heady scent.

Early summer also heralds the arrival of alliums, whose blue or white pom-pom flowers provide a focal point in the border.

Don’t forget to include some late-summer flowers in your scheme, which will appear from August onwards.

This includes deep orange helenium, bright yellow rudbeckia and crocosmia in shades varying from yellow to deep red.

Lillies should be bursting open in mid-summer, while border phlox will only start flowering when summer is well under way.

The white or pink flowers of the low-growing ice plant, Sedum spectabile, will be a magnet to bees and butterflies in the late summer border, while tall-growing princely dahlias look great in mixed borders for a sub-tropical look and blue hydrangeas provide late summer interest both in beds and large pots.

July and August are not ideal planting times if you don’t want to be a slave to the watering can.

You’re better off focusing on deadheading, watering and feeding plants which are already established.

Autumn

If you want swathes of daffodils, crocus, alliums and snowdrops, autumn is the best time to plant spring-flowering bulbs.

Crocus and narcissi can be planted at any point until early December, tulips should be left until late autumn, while snowdrops and other small bulbs are best planted immediately after purchase.

As a rule, plant bulbs at three times their depth below the surface of the soil or compost.

If you have planted an area of flowering prairie, it should be approaching its pinnacle in September, while shrubs which were planted in spring including buddleia davidii, hydrangea, escallonia and Ceanothus ‘Autumnal Blue’ offer further colour.

Replace summer bedding as it comes to an end with plants for winter and spring, and plant winter bedding and spring bulbs in containers this season.

Autumn is also a time when brilliant leaf colour comes into its own, whether you have stunning Japanese maples (acers) in pots or borders, katsura trees, which turn through every shade of yellow, pink, orange and red as the season progresses.

Berries also appear in shades of orange, yellow, red and black, on stalwart shrubs such as pyracanthas, cotoneasters, sorbus and Rosa rugosa.

Autumn is also a great time for planting container-grown trees, shrubs, climbers and roses, while the ground is still warm and workable, while in late autumn you can begin to plant bare-root plants, provided the leaves have fallen off and the plants are dormant.

When Can I Plant Flowering Plants in Spring?

There is such a wide selection of ornamental annuals with different cultural needs that many gardeners do not know when to plant in the spring. Annual flowers differ in their tolerance to cold weather and frost. Some annuals are cold tolerant and will survive a light frost. Cold tolerant annuals can be planted before the last frost date. Generally, the genetic cold tolerance of plants varies depending on where the plant originates. Annuals native to tropical regions are sensitive to cold soil temperatures and are easily damaged by frost. Tender annuals should not be planted outdoors until after the last spring frost. Cold tolerance information is sometimes found on the label of the plant or on signage at the garden center.

Acclimating Plants for Outdoors

In addition to knowing the cold tolerance of the plants, it is important that the plants be acclimated (hardened-off) to outdoor conditions. The acclimation process helps plants to adapt to freezing temperatures. Ask your garden center if plants have been acclimated, or you can acclimate them yourself. To acclimate plants, place them outdoors in a protected area during the day and bring plants back indoors at night for one to two weeks. Providing cool temperatures with limited exposure to wind will acclimate them for outdoors. During the second week, plants can be left outdoors unless freezing temperatures are expected.

Here are some guidelines for deciding when to plant flowering plants.

Average Frost-Free Date

Know the average date of the last frost in the spring for your area to use as a guideline for planting. The fact sheet “Massachusetts Frost/Freeze Occurence Data” is available from UMass Extension, or ask your local garden center, or search on-line, “Massachusetts frost free dates”.

Workable Soil and Soil Temperature

Flowering plants that are planted in soil that is too wet and cold will not grow, and are prone to root rot and nutrient deficiency. The moisture level of garden soil is considered adequate for planting when it is workable. Workable soil is no longer frozen and it is not too wet. To determine if the soil is too wet to work, squeeze a handful of garden soil in your hand. Workable soil should fall apart easily and not stay clumped together. If it sticks together the ground is too wet to work.

Soil temperature also plays an important role. Some plants will tolerate cool soil, while others require warm soil.

Measure soil temperature by inserting a soil thermometer about 4″ into the ground. Take a measurement in the early morning and late afternoon to get a high and low for the day, then average the temperature readings. Measure soil temperature on sunny and on shaded areas of the garden.

Also, the UMass Extension Landscape Message provides soil temperature information in areas of Massachusetts under “Environmental Data”.

To help soil to warm faster, try one of these tips:

  • Pull back organic mulch (if it is in place in the garden), to allow the dark colored soil to warm faster. Once soil is warmed and plants planted, mulch can be raked back into place.
  • Lay a sheet of clear plastic over the garden area to warm the soil and trap the heat. Remove clear plastic before planting. Note that weeds will grow quickly under clear plastic as the soil warms. Black plastic can also be used to warm the soil and it will suppress weed growth. Black plastic is a little less effective than clear plastic because it absorbs and deflects some of the heat.

Plants and Planting

As soon as garden soil is workable and soil temperature reaches 45°F, bare root perennials and very cold tolerant annuals such as pansies and violas can be transplanted. Soil temperatures between 45° F and 65° F are best for pansies. Pansy roots will not function when soil temperatures are below 45°F.

When soil warms to about 65°F (about two to three weeks before frost-free date), cool tolerant plants can be planted, such as nemesia, diascia, snapdragons, alyssum, osteospermum, mimulus, lobelia and petunias. Most potted perennials that have been acclimated can also be planted at this time.

Tropical and subtropical warm crops such as alternanthera, angelonia, New Guinea impatiens, lantana, vinca, celosia, cleome, coleus, cosmos, gomphrena, ipomoea, melampodium, portulaca, sunflowers and zinnias should be planted after the threat of frost has passed in warm soils (minimum 68-70°F). These plants are naturally sensitive to cool temperatures and are not a good choice for early spring planting.

Patio Pots and Containers for Earlier Planting

To get a jump on the growing season and to avoid cold, wet garden soil, try growing plants in hanging baskets, patio pots or other above ground containers. Flowering annuals can often be planted in containers above ground earlier in the season than those planted in the ground. Soilless mixes are used in containers which tend to be warmer and drier than garden soil, especially if containers were recently filled with new growing media that was not kept outdoors over winter. However, air temperature should still be taken into consideration and tender plants should not be planted before the danger of frost has passed.

Monitor Weather and Frost Protection

Monitor the weather forecast for all flowers planted in early spring, and if a frost is predicted, cover tender plants with a sheet or cold protection crop cover (commercially available) for frost protection. Without some sort of protection, you are always taking a chance when planting outdoors in early spring and occasionally plants will get damaged. By choosing cool tolerant plants, acclimating plants, planting in workable soil, closely watching weather forecasts and providing extra protection when needed, you will minimize the risk of losing plants.

References and Resources:

Meyer K. Is It Time Yet? Proven Winners.

Plant Your Annuals by Soil Temperature. 2013. Prairie Star Flowers Blog. Kansas State University Research and Extension.

Wade G.L. and P.A. Thomas. Success with Pansies in the Winter Landscape: A Guide for Landscape Professionals.University of Georgia Extension.

Ophardt M.C. 2014. Soil Temperature: Is the Soil Warm Enough for Planting Seeds? Washington State University Extension.

Annuals and Perennials for Early Spring Planting

When we have a long, “normal” Canadian winter, it is exciting to work with the first outdoor plants of the season. This usually happens in April and has in the past comprised of mostly pansies and early perennials. These are what the horticultural trade calls cold weather plants and they can live and grow in cool, inconsistent temperatures, often below freezing.

Recently we’ve become more aware of choices available in this category, which allows us to now have more creativity in the containers and garden designs we create in Spring.

Cold weather annuals are annual (living only one growing season) plant varieties that perform well, and some even thrive, in cold temps. These cold temps can occur at either the beginning or end of the season. An example of such an annual is the pansy. It is strong, sturdy and full of bloom in the Spring, floppy and non-blooming in the heat of the summer and then, if trimmed of excess growth, strong and lush in the Autumn again when the cool weather blows in again. Other annuals that do well in cool weather include argyranthemum, alyssum, gazanias, osteopermum, verbena, dianthus, petunias, ivy, bacopa, diascia, and dusty miller. All cold tolerant annuals can best handle temperatures below zero (to minus two or three) at night when they are well watered in the day. If it is extremely cold, watering off the frost prior to sunrise will eliminate damage to the plant.

Early Perennials (living more than one growing season, bloom and grow from year to year) can be planted in the ground in April, although in the cool ground they may not thrive until the soil is warm later in May or June. This will also depend on where you live and the sun exposure of the flowerbed. Some early perennials include: heuchera (coral bells), primroses, columbine, saxifrage, bleeding hearts, iberis, campanula, brunnera, hellebores, ground phlox, dianthus, forsythia and dwarf iris. Spring flowering bulbs such as tulips, daffodils and the like also fall into this category.

Cold weather annuals and early perennials can be used in combination in your first container combinations of the season. Lovely combinations can be made with curly willow branches as the height in the centre of a container, hellebores, osteospermum, colourful coral bells and fuzzy dusty miller as the filler plants with alyssum, ivy and pansies spilling over the edges of the pot. Or consider a simple, petite combo of pansies and ivy with pussy willow branches piercing the middle of the arrangement.

A benefit of using cold weather annuals and early perennials as container plants is that they can be repurposed. The perennials can be planted in the ground when your Spring arrangements are ready to move on to a Summer look; be sure to remove them gently from the container and water in with a root starter fertilizer to ease the transition. The annuals can be reused in other arrangements or flower beds or cut back (in the case of pansies, alyssum and diascia that may become overgrown once the heat sets in), planted in partial sun to ride out the summer and brought back into the forefront when the weather cools again in the Autumn.

Don’t get caught up in the excitement of Spring and plant or containerize varieties that are not cold tolerant! Some stores (not usually your quality local garden centres) will present any or all plants they can as soon as the weather becomes warmer. In April it is too early, in our area, to have geraniums, begonias, impatiens, potato vines and the like outside in our inconsistent temperatures. If you get the bug, refer to this guide, or to knowledgeable garden centre staff, for suggestions on cold tolerant plant options.

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