Gardening Tips: April 21, 2010

Sequence of Bloom
I just returned from my annual driving trip to Florida and I am happy to see that all the snow has finally melted around my property. When I left in late March there was still more than a foot of the white stuff in my woods. Ironically, temperatures in Albany were actually warmer than Florida for almost a week. The thermometer hit 91 degrees in Kingston one day and the high in Clearwater, Florida was only 78! When I arrived in the Carolinas the last week of March very little was in bloom but on the return trip, two weeks later, the landscape was exploding with azaleas, dogwood, redbud, wisteria and even roses!

The sudden onset of warmth locally has deluded many anxious gardeners into thinking it will remain warm until this fall. Don’t be in too much of a hurry to get things growing outside. The last average frost date for much of the Hudson River Valley region is between April 15 and April 20. For areas 10 miles or so inland, the average date is between April 20 and May 5 and for those of us who live at higher elevations in the Catskill Mountains, we can still expect frost as late as Memorial Day! Last year I had frost in early June on my north-facing yard.

For years now I have been encouraging gardeners to buy and use a soil probe type of thermometer to judge the proper time to plant. Very few garden plants grow well when the soil temperature is still below 50 degrees regardless of the air temperature. In fact warm air temperatures will put more of a stress on the root systems of plants as the plant tries to take up water for photosynthesis. This can result in problems later this season. Tomato plants with flowers already open now commonly produce fruit with blossom end rot later on. Blossom end rot is a condition in which the tomatoes develop a black spot on the bottom of the fruit just as they start to ripen. Other transplants will develop symptoms that appear to be nutrient deficiencies such as yellow or purple leaves, stunted growth, tan colored spots on the leaves and wilting. All of these problems are due to cold soil and usually will cure themselves in a few weeks, if the plants survive! As my friend Ken, from Story’s Nursery says, “Plant early and plant often.”

Many vegetable garden transplants are seriously overgrown in their cell packs by the time they are set out and this will reduce yields later on. It takes about six to eight weeks to grow an optimum sized tomato plant from seed and less than four weeks to grow a cucumber or summer squash transplant. Although plants in the cabbage family such as broccoli and cauliflower can tolerate colder temperatures and even some frost, they will often “bolt” (go to flower prematurely) when subjected to temperatures in the 40s.

If you just cannot wait to start growing vegetables outdoors, consider planting in containers or window boxes. Lettuce, spinach, other salad greens as well as radishes and beets can be grown in containers now with good results and raised beds often will be ready to plant as much as two weeks before the rest of the garden is ready.