Renewal is the essence of gardening—whether pinching back leggy petunias or spreading compost—and is essential for a healthy garden. But within the community of a garden bed, plants are apt to wander and mingle, sometimes even overtaking their neighbours while gobbling up nutrients from the soil. And despite efforts to keep plant relations civil, there comes a point when some serious attention is in order.
You can renovate a garden bed throughout the growing season, but autumn is a particularly good time, when desired changes are fresh in your mind. Regardless of whether you tackle the whole bed at once or in sections, plants will benefit greatly from improved soil structure and the renewal of nutrients, and reward you with a bounty of bloom in coming seasons.
Cleaning house (assessing and storing plants; weeding)
The goal of renovating a garden bed is to create the best possible soil conditions for the healthiest high-performance plants. Begin by objectively assessing the bed's perennials, assigning each a performance rating: “performs well,” “shows strong growth and potential” or “has frequent problems.” Unhappy plants may be unable to adjust to the light and moisture conditions of the location, and might be more productive elsewhere. (Roses and peonies, for example, have little to offer in a shade bed but will bloom prolifically in brighter light.) Poor performers should be removed, along with other plants that have ongoing insect and disease problems, such as hollyhocks with chronic rust disease or phlox cultivars with mildew. Determining which plants should be eliminated may seem like parting with old friends, but no gardener enjoys watching a plant struggle; it's better to replace it with a new selection more suited to the site.
Once plants have been rated, both strong and poor performers should be carefully lifted with a spade and put into containers or a box lined with plastic. Cut back foliage if you're renovating the bed in autumn, but allow undamaged leaves to remain if working during spring or summer. Keep enough soil around each plant to avoid breaking up the root ball. Individual plants can also be placed in plastic bags with holes poked in the bottoms for drainage. Also remove clumps of bulbs buried in the soil and put them in plastic bags; leave the bags open for airflow.
Store those plants you're keeping in a cool, shaded spot. Water them in their plastic bags or containers right away, and every day that they're out of the soil. Rejects or invasives can be given away or contributed to a garden sale.
If the bed also contains shrubs, consider their size and performance. Those that are too large (such as some lilacs, viburnums, forsythias and weigelas) may need to come out and be replaced with dwarf varieties. Remove any shrubs you're not keeping, but don't disturb those that are staying. Instead, prune any dead wood from the shrubs and thin out any interior branches that are crowded or crossed.
Finally, remove all weeds. Dig out the full root systems of those that are perennial, such as dandelions, plantains and thistles. Any roots remaining in the soil will soon sprout leaves and continue to grow even better in the renovated bed.