For the First Half of the Month:
On warm days, go outside and check your perennials and bulbs to see if they have been heaved out of the ground by freezing and thawing of the soil. If so, press down firmly and cover with at least two inches of organic mulch.
Thoroughly check your houseplants for pests. If you find any, treat these immediately before populations get too high.
Another common problem of houseplants this time of year is the low humidity that is in most homes during the winter. One way to increase the humidity is to place plants over, but not in, trays which have water in them.
In addition, low-light levels in your home may be causing some problems and may need to be adjusted. Move plants that normally do best on the north side of the house to an east window. For those plants that are ordinarily in the east windows, move them to a south location.
Review your vegetable garden plans for the upcoming season.
If you bought a live ball-rooted Christmas tree, remember to water it. It can be planted outside as long as the soil can be worked.
For the Second Half of the Month of January:
Sit down on cold, snowy, or rainy days with newly received garden seed catalogs. Compare new varieties. An important consideration is improved pest and/or disease resistant seeds over older varieties.
Pull out and check your notes from last year’s garden. Reorder the varieties that you had success with and any new ones you may want to try.
Start a pot of shamrocks to have ready by St. Patrick’s Day in March.
Start pansy plants from seeds indoors. They should be ready to transplant outdoors in mid-March to bloom with spring tulips and daffodils.
Begin bringing in the pots of bulbs prepared for forcing last fall. Place in a warm
60-65oF shaded location. Move to a sunny spot when you see green leaves begin to show.
Begin dormant pruning of fruit trees and grape vines now; try to finish before March.
Apply horticultural oil sprays to kill over-wintering mites, aphids, and scale. Use this oil on deciduous plants and hardy evergreens, but not on needle-leaved species. Read and follow label directions.
Spray oils when temperatures are above 40oF, but not within 24 hours of a freeze (watch the local weather stations for this information).