At this time of year the garden is entering a quiet time of rest and dormancy. The colder temperatures of winter give a needed rest to those plant species from temperate regions. This is an important period for many plants as it provides a rest which will issue in a grand flush of growth in the coming growing season. If plants do not get this cold period rest, they will grow, but not as vigorously as they would had they been given the proper cold rest period. Flowering and fruit species display this most evidently. Their spring bloom is profuse if their cold requirements were met, and the show of blooms is meager if it has not.
For tender and semi hardy species, this is cold is not welcome and they will need frost protection to survive. Do not prune off frost burned parts of plants now, those damaged areas will provide insulation against future cold spells and if pruned off now, they can actually initiate a growth flush, which is not what you want at this time.
Provided you have planted cold hardy species in your landscape, they will need minimal attention now. Adding a mulch can give roots more frost protection but be sure to check it when growth starts in late winter or early spring. Clear it away so new growth can grow without restriction of the added mulch at the base of the plant. Many perennials benefit from a cold dormancy period. Herbaceous peonies are a prime example. The dormant buds need that cold period in order to bloom. Other perennials like this cold and they will show it in spring with a grand flush of top growth. You can actually divide many perennials now and they will do much root growth to support the spring flush of top growth.
With exotics like bamboo, now is a prime time to divide them as they are in a state of dormancy or semidormancy. Be sure to keep the plants from dessicating and keep them in a wind and sun protected area until small feeder roots can grow in about a month or two.
With early flowerers like flowering quince, forsythia, chimonanthus, and winter honeysuckle bush and flowering plums, this cold rest period now will yield a very fine show of blooms later on. In warm winters,, their display of blooms is meager compared to what it will be this coming season since we are having a typical winter’s cold.
It is very important to make sure all plants are kept well watered during the winter. This is especially important for camellias, rhododendrons, azaleas, and pieris. If you let them go dry now, the flower buds will abort. Deciduous species are less exacting but keep an eye on them as well to make sure they have enough water to keep the stems plump.
Winter pruning can be done now on some types of plants. Removal of dead growth and poorly placed branches can be done at any time, but is easier to see now when leaves have fallen. I tend to like to prune toward the end of winter so cuts will be exposed less to the cold and growth will begin soon after when spring arrives.
An important thing to remember is that for plants that bloom on old wood formed last year, winter is not a good time to prune them as you will be removing the flower display of spring. Prune those plants during or just after they bloom so new growth will come after the bloom period and have time to ripen over summer and fall and give branches of bloom next spring. (Deutzia, forsythia, chaenomeles, philadelphus, weigela are examples of these.)
Winter is an excellent time for garden clean up. Clearing away any debris is always a good idea as santitation will eliminate hiding places for bugs and diseases to a very great extent and lessen the need for possible spraying later on.
A dormant oil spray will eliminate many insect pests before growth starts. I like to time spraying after rainy periods and towards the end of winter. With peach leaf curl, you can miss many early season sprayings but not the last one as that is the most important before growth initiates. If you do not spray for leaf curl, you will likely have it on new growth and into summer, and the tree will be compromised. They do not usually die from this, but are set back since infected leaves fall and spores are again released to afflict growth next year
conifers benefit from a cleaning out of dead thatch type growth in the interior of the plant. now is a good time to attend to that job and rains/wind will help with this as well.
You can prune many of these now, keeping in mind the basic overall form of the plant and the interior branch structure. They bleed sap less at this time and you can use the cut branches for indoor arrangements.