Home Gardening Center Tip Sheet: Late-Season Container Gardening

By Sonia Uyterhoeven

You can have a colorful garden throughout the year, even if you do not have your own backyard. In September and October simply plant your summer containers full of cool-season plants. Here are some tips for creating a late season container garden.

Container basics

- Try to plant in early fall while the soil is still warm to establish a good root system.
- Place container in a bright, protected location away from strong winds.
- Use containers that are 14 inches in diameter or larger and are made out of non-porous material so they do not crack during a cold spell. Larger containers have greater volume and therefore better insulation against cold weather. Polyresin pots (polyethylene containers) are designed to look like terra cotta and are well-suited for winter plantings. Make sure that the pot has good drainage holes.
- Use a potting soil that has good drainage. Adding compost to the mix helps to creates additional heat and adds nutrients (4:1 potting mix to compost ratio or less).
- Use a slow release fertilizer that will last until spring.
- Select plants with a hardiness rating colder than your temperature zone.
- Try underplanting with spring-flowering bulbs. Plant bulbs in containers at regular depth (three-times deeper than the height of the bulb), but space them closer together than you would in the open ground.
- Create long-season interest by selecting a mixture of low growing conifers, broadleaf evergreens, grasses, and interesting foliage plants.

Winter care for your containers

- Water when soil is dry and especially at the onset of severe cold weather. Moist soil freezes more slowly and creates heat which protects the roots of your plants. Water in the morning to allow the plants time to absorb the water during the warmth of the day. Do not water if the temperature is below freezing.
- Group containers together--this will create added protection from the elements.
- If temperatures are going to stay extremely low for a long time, either wrap your container with bubble wrap or fill a garbage bag with newspaper (twist newspaper as you would when building a campfire or insulating a package) and wrap around containers.
- Winter protection should only be done after the plants have acclimated to the cold but before danger of subfreezing temperatures. Late November is usually a good time for this in our area.
- A few favorites for fall containers are chrysanthemums (Chrysanthemum), annual salvias (Salvia), hellebores (Helleborus), coral bells (Heuchera), bergenia (Bergenia), ornamental grasses, and ornamental cabbage and kale.
- A few favorites for winter containers are heath (Erica), heather (Calluna), osmanthus (Osmanthus), skimmia (Skimmia), and conifers.

Why do leaves change color?

Chlorophyll, which gives leaves their green color, breaks down in the fall when temperatures drop and days get shorter. Yellow and orange pigments (carotenoids) that have always been present in the leaves now become visible while red pigments (anthocyanins) develop only in the fall. Rainfall, wind, temperatures and the amount of sugar in the leaves all influence the intensity of the foliage. Cool, bright, sunny days and chilly nights (with no frost) create the brightest colors.

Download this Tip Sheet.

Generous support for the Home Gardening Center has been provided by Kenneth and Ellen Roman.