Compare sizes. A 1-gallon pot can sometimes be priced very attractively compared to a 4-inch pot -- or maybe not. Also, if the 1-gallon plant is mature enough, you might be able to divide it upon planting into two or three plants.
Check plant hardiness. Labels give a general idea of what climate a plant will tolerate. Check it closely or your perennial just may be an annual; that is, it will die out over the winter.
Find your USDA Hardiness Zone.
Buy enough to make an impact. Few gardens look good with one perennial tucked in here, another tucked in there, yet another over there. As a rule, buy at least five or six of one perennial so that you can create a cluster in your beds and borders.
Don't forget fall. Fall is a great time to plant yoru favorite perennials. See what your garden center has and take advantage of those crisp fall days to do a little digging.
Test Garden Tip. In fact, fall is the ideal time to come up with stunning combinations of bulbs and early blooming perennials.
- Bare-root vs. container vs. balled-and-burlapped. Bare-root is a good way to plant when the weather is very cool, usually in late winter or early spring, a couple of months before your region's last frost date. Bare-root plants don't have leaves yet so they're not much stressed by frost and other climate extremes. Container-grown plants as well as balled-and-burlapped plants are planted anytime from spring to fall, though they're usually a little more expensive.
- Make sure it looks healthy. If it looks healthy, it almost certainly is. But don't buy sickly or diseased plants just because they've been marked down.
- Check the roots. If the roots are bulging out of the container, the plant is very pot-bound and may have a tough time getting established. On the other hand, if the plant seems very small in its pot but otherwise is healthy, ask the garden center staff if you can knock it out of its pot to check before purchasing. It may just recently have been planted and not well established. It will take more time to get to mature size. You'd do well to look further.
- Consider size. A plant that is labeled as reaching 40 feet tall and 15 feet across is a big plant. Take size into consideration and envision it in its home. If you're unsure, take a deep breath, go home, and measure. A tree too big for its spot is an irritation you'll have to live with for years.
- Jump start roots. If you just spent $30 on a tree or shrub, spend a little more on one of those fertilizers designed to stimulate root growth. They're a good investment.