Avoid common mistakes in the perennial border

As a new gardening season begins, avoid these common missteps to keep your perennials healthy and your borders beautiful.

Gardening mistake No. 1: Buying perennials in full bloom

While it is tempting to purchase plants bursting with blooms, they may not be the best buy. Perennials covered in color offer tempting instant gratification, but bud-laden plants save all their color for your garden.

It may not be as important when purchasing perennials that bloom all season, but some perennials on garden center benches in spring have been forced to bloom earlier than they would if they were planted in the garden. Others are one-season-and-done bloomers so fully-flowering perennials are at the end of their color show. Let them bloom in your garden, not at the garden center.

Garden mistake No 2: Planting perennials in the wrong spot

It doesn't matter how perfect the color and texture of a hosta is in a garden design if the design is meant for a sun baked border, where the hosta will burn to a crisp. And considering the light requirements alone is not enough. Just as lavender and thyme quickly rot in wet soil, blue flag iris and marsh marigolds fizzle in dry conditions.

Before purchasing plants, do a little research. Observe how the sun moves across the landscape. Is it sunny all day or do the rays fall for just a few hours? If it is just a few hours, is it sunny in the morning or the afternoon? Evaluate the soil. Does rainwater quickly drain from the area or is the soil moist for days? Is the soil heavy with clay or has it been amended with lots of compost?

Use reliable sources to learn about plants. Borrow books about perennials from the library, surf trusted websites, read plant tags and quiz staff at local garden centers.

Gardening mistake No. 3: Positioning perennials too close together

It takes discipline to plant perennials at their recommended spacing. However, giving plants room to mature reduces the chances of fungal diseases when they are full grown. Perennials planted too close together also have to be divided sooner.

Gardening mistake No. 4: Loving perennials too much

Gardeners are nurturing by nature and want to help their perennials grow. Overwatering, overfertilizing and over-mulching are all common gardening mistakes. Water plants thoroughly when planting and then let the soil begin to dry before watering again. Overwatering probably kills more plants than any other gardening mistake.

Many also believe if a little fertilizer is good, more must be better when, in fact, the opposite is true. Too much fertilizer can burn leaves and roots or force lush growth susceptible to attack by insects or disease. Many perennials don't need fertilizer at all if the soil is amended and top dressed with compost on a regular basis.

Gardening Mistake No. 5: Letting weeds go to seed

The seed heads of weeds contain hundreds (or even thousands) of seeds that spread across the landscape. If conditions aren't appropriate for them to sprout and grow immediately, they are able to remain dormant for years waiting for their opportunity to germinate. Pledge to pull weeds before they form seed heads and save yourself years of weed pulling.

• Diana Stoll is a horticulturist, garden writer and speaker. She blogs at gardenwithdiana.com.