Marianne Binetti

Time to look for slug eggs, liberate potted plants

The second week of October is a good time to search for and destroy newly laid slug eggs, especially while planting bulbs or harvesting from the vegetable garden.

The eggs will look like tiny pearls in clusters of 50 to 100. Check under stones or mulch and along the edge of lawns for those hiding eggs.

Q. I loved your article about year-round container gardens in September, but want to know how long my perennials can survive in a large container that is 24-inches wide and about as deep. I have grown hosta, euphorbias and evergreens in this pot for years, but the plants always seem to decline in health after a few years. T.H., Olympia

A. Potted perennials and shrubs can get too chilly, too dry and too hungry after several years trapped in a container. October is a good month to remove overgrown potted perennials and shrubs. Score or cut into the crowded root ball and replant them into your garden beds.

Do not wait until spring because freezing winter weather is very hard on a root-bound plant trapped in a pot. If the potted plant is an evergreen shrub, you can try root pruning or shortening all the roots by one third. Then add fresh potting soil and replant the old plant back into the container.

Every potted perennial will appreciate a blanket of compost mulch this time of year to insulate the roots from the coming cold. If you do decide to empty your pots now, there is still time to replant with fall flowers such as mums, winter pansies, and ornamental cabbages and kale. Add a few mini pumpkins as a mulch and poke a cut branch of maple leaves or autumn berries into your new fall planting and celebrate the change in seasons.

Q. Which plants need to be fertilized in the fall? I did feed my lawn a fall and winter lawn food a few weeks ago, and it looks better than it has in years. K.L. Renton

A. Fall is a good time to fertilize the lawn, but please do not fertilize any of your other plants in October. The shorter days and colder nights are Mother Nature’s way of coaxing plant life into a long winter nap so they will not suffer from the freezing weather ahead. Fertilizing keeps plants awake and producing tender new growth.

Spreading compost or mulch on top of plants is preferred over sprinkling a fall fertilizer. Compost is not a fertilizer but rather a soil conditioner that will provide some slow release nitrogen when the weather warms up in spring.

Q. When it comes to fall cleanup, which perennials do I cut back and which do I leave alone? I have some ornamental grasses that still look great. When do these need to be cut back? B., email

A. Here’s a rule of green thumb — when it’s brown cut it down. If it’s green, leave it be. This means you can leave the ornamental grasses, sedum autumn joy and Rudbeckia seed heads for the birds to enjoy all winter, but in early spring when you see the forsythia in bloom, cut back the brown clumps of ornamental grass to make way for the new spring growth.

Do not prune evergreen grasses such as black mondo grass, sedges or carex. Always collect the soft damp leaves of hosta and cut back delphiniums now to discourage overwintering slugs. October is a good month to dig up and remove perennial plants or shrubs that did not perform well or were just too demanding. Fill the empty spot with fallen leaves and debris to rot over the winter so the soil will soften up and be ready for a new plant in the spring.

Marianne Binetti has a degree in horticulture from Washington State University and is the author of several books. Reach her at binettigarden.com.

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