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.
March is a really good time to plant spring flowers, particularly if the last frosts have passed. If not, be sure to only put in frost-tolerant plants for now. Otherwise, wait until spring warmth is more consistent before putting in spring flowers.
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.
In general, wait until the temperatures range from 60 to 70 degrees Fahrenheit to plant tender vegetables like corn, tomatoes, peppers, eggplants, okra, summer squash and beans. Use a soil thermometer to make sure the soil is warm enough to plant.
Generally speaking, spring-flowering bulbs should be planted in the fall (a few weeks before first frost), while summer-flowering bulbs should be planted in the spring (a few weeks after last frost).
While you can plant a late planting to the first frost date, it's always best to allow as much growing time as possible. If you missed the spring planting, then calculate which vegetables you can grow now and still have a harvest before the first frost.
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.
Good choices are summertime kitchen garden staples like squash, beans, cucumbers and melons. Beans (Zones 3-10): You can plant both bush and pole beans now that the soil and air are warmed up as beans should not be started indoors. Try a continual 7-10 day sowing of different varieties.
The Basics of Planting Annual Flowers
Tender annuals — Tender annuals thrive in warm soil and warm air temperatures. They should only be planted once temperatures reach and stay above 55°F. They can be severely damaged or die if they are exposed to frost or temperatures below 32°F.
Generally March and April, when the soil begins to warm, are the best months to begin sowing many hardy annual vegetable seeds outdoors including broccoli, cabbage, chard, carrots, peas and parsnips.
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.
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.
Plants and Planting
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.
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.
The easiest time of year for flowers by month is through mid-spring and early summer. This is a time of abundant blooms in all climate zones. For many areas the toughest time to find color in your yard is the colder months. Some of the coldest areas may need to look to indoor plants for their wintertime color.
Light freeze - 29° to 32° Fahrenheit will kill tender plants. Moderate freeze - 25° to 28° Fahrenheit is widely destructive to most vegetation.
Some cool-season annuals can tolerate soil temperatures as low as 45 degrees Fahrenheit; however, most cool-season annuals will grow best in soil temperatures at 65 degrees Fahrenheit or warmer.
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.
Explanation: Water, air, and sunlight are the most important things that a plant needs for growth. Plants take in carbon dioxide from the air and convert it into glucose through the process of photosynthesis, which is powered by sunlight.
Winter time is very hard on flowers. They just do not like any temperature below freezing. Don't get me wrong flowers like it cold. Flowers are happiest in temperatures of 40-50 degrees.
I did some research and found out that houseplants need to be taken indoors before overnight temperatures dip below 45 degrees. Most tropical plants suffer harm from temperatures below 40 degrees.
With that in mind, experts generally recommend flowers and other houseplants be brought inside or otherwise protected before the thermometer dips below 45 degrees Fahrenheit. For warmer-weather and tropical plants, that threshold is a bit higher, at around the 50-degree mark.