Planting. Most perennials should be planted in the fall or early spring. Fall planting gives the plant more time to become established before the start of active growth in the spring. Fall-planted perennials are usually well-established before hot weather.
They are best to plant in the spring, after the last frost, when temperatures are between 45°F – 60°F. Purchase bare root plants when you can plant them right away, so they don't dry out. When planting a bare-root perennial, dig a hole twice as wide and as deep as the root ball.
You can transplant perennials anytime until the ground freezes in the fall, or wait to transplant them in the spring. Fall is an excellent time to transplant herbaceous perennials because your plants will then have three seasons to establish a good root system before hot summer weather sets in next year.
Perennials. The newly emerged growth of most perennials can tolerate temperatures in the low 30s and upper 20s °F. This includes many early emerging perennials such as bleeding heart, daylily, catmint, and columbine. In most cases, early leaf growth on these plants will be just fine with cold temperatures.
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.
A hard freeze in May is not uncommon for some areas and can kill tender perennials. Hardy plants such as daylilies, hosta, peonies, lily-of-the-valley will survive a late spring frost, but they will be out of commission until warmer weather returns.
Perennials are slow growers at first: They take the first one to three years to establish deep roots and dense foliage. However, once established, they thrive with little maintenance to give your yard beautiful new growth year after year.
1) Plant before frost. Check your local area's frost estimations and plant perennials at least 6 weeks before the first freeze. 2) Don't fertilize -- fall-planted perennials will be going into winter dormancy in their next stage of life and new growth (encouraged by feeding) will be killed when the first frost comes.
Frost Tolerant Perennials
Those that are frost tolerant can be planted 2-3 weeks before before the last spring frost to give you some immediate color and interest in your gardens or containers. Be aware though, that they may need to be acclimated to the cold weather.
Plants and perennials that require additional protection to survive your winter will need a deep layer of mulch added by mid November or later, when the ground is beginning to freeze. Do NOT add deep mulch too early or your plants will not be slowly exposed to colder temperatures, allowing them to acclimate for winter.
It will also freeze sooner and thaw more easily than the ground, and it may freeze and thaw several times during the winter, putting stress on the plant. So a potted perennial must be bone-hardy in your area and colder to survive in a container with no special treatment.
Spring-blooming perennials, especially in the bare root form, are best planted early in the fall. Planting in the fall while the soil is still warm will give the roots enough time establish properly. This allows the plants to emerge from well established roots, with a stronger start, the following spring. 4.
Some perennial flowers will thrive in areas with low sunlight and come back every year. Astilbes are some of the easiest perennials to grow and will open their plume-like flowers in partial shade. They'll even grow in full shade, although you won't get as many flowers. Hostas are also a good choice for shady spots.
Water and Feed Your Perennials
Young perennial plants may be hardy, but they still need plenty of water and nutrients to get established in the soil. You can easily water and feed at the same time with Miracle-Gro® Liquafeed®.
Some Sun. Some Shade. So many perennial varieties are vesatile players, thriving in areas with part sun. If the sun in your garden is intense afternoon sun, be sure to provide adequate water or site more sensitive plants in shadier locations.
You can sow seeds for winter vegetable crops, like salad greens, radishes, carrots, onions, Swiss chard, English peas and kale. Look for transplants of other cool-season vegetables, including Brussels sprouts, broccoli and cauliflower. Herb transplants also appear in garden centers during winter.
Some perennials, like hostas, peonies and daylilies, need to be pruned in fall to avoid winter damage. Plants like these should be pruned after the first few frosts in late fall or early winter. Other perennials like mums and coneflowers are better off being pruned in spring just before new growth comes in.
It's common to think that everything should be chopped down to the ground in the fall, but some perennials actually need their foliage to protect new shoots through the winter. Other varieties offer up important habitat for local wildlife and some perennials provide height and interest through the winter months.
While not all perennials need time to look and do their best, this is a common enough phenomenon that there is an actual adage for it "The first year they sleep, the second year they creep and the third year they leap!" But what does that really mean?
Most perennials grow best in soil that is well drained with good fertility and a pH of 6.0 to 7.0. Adding organic matter to soil improves the fertility, texture, and water-holding capacity.
Spring Perennial Plantings:
Week 1: Every day to every other day. Weeks 2-3: Water 2-3 times per week, depending on environmental conditions. Weeks 4+: Water 2-3 times per week, more in hot/dry conditions.
Bulbs and perennials emerging from the ground do not need to be protected from sub-freezing temperatures. They are growing according to nature's schedule. You don't need to protect plants until after we've had an extended warm period.
Thoroughly Water plants if it's not going to rain before the freezing temperatures arrive. It may sound illogical. However, a moist ground stays warmer than dry soil. Watering the night before the freeze comes will insulate the root structure of the grass and plants and decreases the potential for cold injury.