Preparing the Garden for Winter

As fall approaches, it is time to take on the task of garden clean-up. Fall is also a great time to consider planting trees and shrubs, and many perennials thrive by being planted in the fall. The key factor in plant establishment is root growth, and the faster the roots grow into the back-fill area of a newly planted plant, the more successfully the plant will become established. Roots never go completely dormant like the above-ground part of a plant, and soil temperature and moisture are some of the primary factors influencing healthy root growth. In the fall, the soil temperatures stay warm and there is usually ample soil moisture with fall rains. Thus the plant has a great head start on root growth before hitting the stressful summer drought and heat the following year, versus planting in the spring in which the roots have only a short period of time to establish before the summer heat and drought. It is also important that a newly establishing plant have time to put adequate energy into root growth. If planted in the spring, the plant is putting energy into foliage and flowers, and less energy is going into root development. However, if planted in the fall, the foliage is already developed, and the plant can concentrate its energy into root development without competing for leaf and flower development as well.

Another important fall task is preparing to move non-winter hardy plants indoors. For many of us, indoor space is very limited and the decision must be make on which plants to over-winter and which to discard. And many of us have started to use tropical plants in our patio containers, and these plants need bright light to thrive through the winter indoors. In some cases, especially if space and light is limited indoors, it may be best to discard your annuals and purchase new plants the next year.

Cannas are fairly easy to over-winter. After the first frost, dig them and cut back the tops. Do not divide the rhizomes at this point as the fresh cutting may rot through the winter. Then store the rhizomes in peat, vermiculite or sand in a cool, dry location with temperatures around 40 degrees F. In spring, cut the rhizomes into pieces with several growing points each and start them as you would new rhizomes.

Tuberous begonias and caladium are also easy to store over the winter. If the tuberous begonias were grown in containers, these plants can be brought in for winter enjoyment and treated as a houseplant. If the planted into the ground, dig up the tubers carefully after the first light frost and remove the top growth. Leave the soil and roots around the bulb intact and place the bulbs in a cool, dry area for 2-3 weeks. Then, remove the soil and remaining roots that should be shriveled by this time and pack the bulbs in peat, sand or vermiculite to prevent excess moisture loss. As with cannas, store in a cool 50-55 degrees and be sure the bulb aren’t subjected to freezing temperatures.

Whatever plants you bring indoors, it is important that you take precautions so you don’t move insects into your house and contaminate other houseplants. Carefully inspect the plants for insects that will proliferate in the warm, dry conditions indoors. If insects are found, it is a good idea to spray the leaves thoroughly with an insecticidal soap or spray with a pesticide approved for use indoors. As you move the plants indoors, isolate them from any other indoor houseplants for approximately two weeks to ensure you don’t contaminate other houseplants.

Other important tasks to remember are to gather up fallen fruit, leaves, or other debris that has fallen and discard. Discarding fallen fruit and twigs aids in reducing disease and insect spread that may be harboring in that material. Fall is a great time to re-seed turf, especially bare patches. And don’t forget to disconnect the garden hose to prevent freezing.

Mary Kroening
Horticulture
573-882-9633