The best month to plant flowers in spring is really down to the USDA hardiness zone you live in and the likely last frost date. This is likely to be from around March, but if you live in a northern zone, be sure to plant frost-tolerant perennials until you are happy that the risk to more tender flowers has passed.
Most flowers should be planted after your region's last frost date. Planting flowers in spring is the most popular time, but perennials do fine if planted in early fall in the North and late fall in the South.
The hardiest of flowers can be planted as soon as the soil in your garden can be worked, even if it's several weeks before the last frost of the season. For half-hardy flowers, hold off until a couple weeks before the final frost, and for tender flowers, plant when there's no chance of frost for the rest of the season.
Gardening in the fall provides a longer period with more 'good' days, as compared to the often tumultuous spring season. Plus, if you plant in fall you'll end up ahead of the game and won't have to rush to get everything done after winter. In fact, a good strategy is to plant perennials when you plant your fall bulbs.
Spring blooming bulbs can be planted any time as long as the ground isn't frozen. Shrubs and trees can be planted, however, earlier in fall is better as it allows for best root establishment before winter. Cold tolerant perennials can be planted, but they will be more winter hardy if planted earlier in fall.
April is a great time to plant many types of flowers. Some of the best choices include pansies, petunias, snapdragons, and lilies. Pansies are ideal for cooler climates as they can tolerate light frost and bloom in bright colors like yellow, purple, or white.
Flowers that come back up from their roots every year in the springtime are called “perennial” flowers. Some of the best perennial flowers to grow in a garden are peonies, daylilies, coneflowers, and hollyhocks.
Plants like chrysanthemums, nasturtiums and asters are wonderful choices for seasonal planting arrangements. While perennials that will survive the winter are great choices, autumn is also a great time to explore new ideas will short-season annuals too.
Not all plants need direct sunlight. In fact, plenty of annuals, perennials, and tropicals can thrive in the shade. Whether you want to brighten up those dim corners in your yard or liven up a spot in the shadow of a large tree, these shade-loving flowering plants happily grow where their full-sun counterparts won't.
Sunlight, water, and soil are the key components of healthy plants. The amount of light your yard gets will change throughout the day as shadows from buildings and tall plants move with the sun. Most plants will thrive in at least six hours of direct sunlight, which is typically referred to as full sun.
You should always leave a foot of open space around the foundation to prevent moisture build up that can lead to mold and damaging dampness (and to avoid giving insects like carpenter ants and termites direct access to your home). Distance is good for the health of the house—and the plants.
The general rule of thumb is that most plants freeze when temperatures remain at 28°F for five hours. Of course, there are exceptions to this rule. Seedlings, with their tender new leaves, often give up the ghost when temperatures dip to 32-33°F. Tropical plants have differing low-temperature thresholds.
The ideal soil temperature for flower seed germination varies greatly depending on the species and variety. Sunflowers, for example, like a soil temperature from 70-75°F (21-25°C) while sweet peas prefer 55-65°F (12-18°C). Soil temperatures between 65°F-70°F (18-21°C) tend to suit many types of flower seeds.
March may be a good time to plant perennials, depending on when your last frost date is. You can safely plant frost-tolerant perennials 2-3 weeks before your last spring frost. Growing spring-blooming perennials is a great way to add a splash of color and beauty to your garden.
Mid- to late-August is often an excellent time to plant fall flowers, as long as the weather isn't still so hot that the plants will suffer heat stress. But don't wait too late to plant, or you'll have a very short window to enjoy your flowers. Check the growing requirements for each plant.
Late summer or early fall is an excellent time to plant mums, one of the symbolic flowers of the season. Practically any time in September that strikes your fancy is a good bet, so long as it's at least six weeks before the year's first frost.
Although each plant's needs may vary and some will be more winter-hardy than others, in general about a month before the last fall frost is sufficient in giving the plant enough time to establish itself and take root.
Brightly-colored flowers that are tubular tend to produce the most nectar, and are particularly attractive to hummingbirds. These include perennials such as bee balms, columbines, daylilies, and lupines; biennials such as foxgloves and hollyhocks; and many annuals, including cleomes, impatiens, and petunias.
The short answer is that annuals don't come back. Plants that flower and die in one season are annuals—although many will drop seeds that you can collect (or leave) to grow new plants in the spring.
Perennial flowers to plant in April
Plant hardy perennials, such as daylilies and delphiniums. Later in the month, when the weather settles, set out transplants of: Forget-me-nots (Myosotis spp.) Foxglove (Digitalis spp.)
Some of the best flowers to plant in May can be grown directly from seed, including poppies, lantana, and sunflowers. Other choices do best when purchased as established plants, such as marigolds or hibiscus plants. However, some flowers planted during this month come back year after year, such as lavender and catmint.