Q. I would like to begin planting some vegetables in my garden, fertilize my lawn and also apply crabgrass and broadleaved weed control. Obviously, the weather this year is a far cry from the warm weather we experienced in 2012. When can I get out and about in the garden?
A. Nature doesnt necessarily cooperate with what the experts say in books and on the Internet. We need temperatures reliably in the mid- to upper 40s and above-freezing temperatures at night to begin our work in the garden and landscape. The process of photosynthesis shuts down when temperatures are below 45 degrees. It does no good to attempt to grow plants or stimulate growth with fertilizer when temperatures are too low.
There are a few exceptions to the rules. If I had a raised-bed garden, I would seed spinach now. Spinach will germinate and flourish in cold weather. In early April, if the weather warms up, I would be planting potatoes, lettuce, carrots and leeks in the garden, followed closely with transplants of broccoli, cauliflower and cabbage toward mid-April.
Gardeners can plant much earlier in raised-bed gardens compared with conventional beds that need tilling in the spring. Its been good news so far that we have received above-normal precipitation this year. This blessing can be a curse to gardeners who want to plant early spring vegetables in conventional truck gardens. One must wait until the soil is dry enough to till. Soil is dry enough to work and till when one cannot squeeze any water from a handful of soil taken from the garden.
Fertilizer and crabgrass controls need to be applied when the soil is not cold and wet. Wait until temperatures are reliably above the 45-degree mark to apply your first lawn fertilizer. The danger of runoff is increased when the ground is frozen, or if we receive copious rainfall when its too cold for the grass to actually use the fertilizer. Nowadays, it is almost a given that one should apply a slow-release fertilizer with little or no phosphorus in early spring. One can use a traditional slow-release balanced fertilizer if a soil test shows low phosphorous. Otherwise prevent nutrient runoff into waterways by using fertilizer responsibly.
Crabgrass will germinate when soil temperatures reach 55 degrees. Well, not everyone has a soil thermometer, so a map that uses growing degree-days and observations statewide to predict crabgrass germination would be helpful. This map that tracks crabgrass germination statewide can be found at http://bit.ly/XcqfVv.
Right now there is plenty of time for homeowners to put down preventive crabgrass controls.
One must wait for broadleaved weeds to emerge before putting down controls. It is usually best to apply when the weeds have begun to appear and the surface is moist.