Cloches protect vegetables planted in early spring. Photo credit: Nancy Knauss
I've had my seed catalogues for over a month, some since Christmas. I'd love to start sowing seeds, but I need to be patient a little longer. Right now, though, I can layout my garden on paper.
Planning is an important aspect of gardening. It's tempting to skip this step, but over time, I've found it is necessary for a successful garden. Plant families should be rotated. Since plants have different nutrient needs, planting the same families of vegetables in the same space year after year will deplete nutrients in that area. For example, potatoes, tomatoes, and other members of the Solanaceae, or nightshade family, are heavy feeders. They have a long growing season and may exhaust the soil’s nutrient supply before setting fruit.
If you don't rotate families of vegetables, insects that specialize on one type of vegetable will easily find their favorite meal again. After feeding on your potatoes during the summer, potato beetles overwinter in the soil nearby and will emerge in the same area the following year.
Diseases are also specific to particular plant families. It is important to clean up the vegetable garden at the end of the season, as spores on infected plant material can quickly infect newly planted crops. Potatoes and tomatoes are both susceptible to early and late blights. If infected plant material is left behind over the winter, the spores can quickly find their host if the area is replanted with potatoes and tomatoes.
A practical reason to plan your garden is to have a realistic idea of what your garden will look like. On paper you can move plants and beds. You can anticipate spacing and how much room the vegetables need. Make sure to include family favorites, as well as any new varieties you want to try. If you decide to trellis cucumbers or beans, you may find enough open space to try a new heat tolerant variety of lettuce.
Once you have finished your plan and ordered your seeds, which seeds should be started indoors, and when? Swiss chard, members of the cabbage family—cabbage, broccoli, kale, etc.—and several herbs can be started indoors in early March. Tomatoes, peppers and warm weather plants that are set out after Mother's Day should be started indoors in early April.
It is tradition to plant peas and potatoes on St Patrick's Day, March 17, but potatoes get the best start if they are planted when the soil reaches 40 to 45°F. Other early vegetables that are sown directly in the garden will germinate best at the following temperatures: lettuce (40 to 80°F), peas (45 to 75°F), turnips (55 to 75°F), radishes (45 to 80°F), carrots (55 to 75°F), beets (50 to 75°F), kale (55 to 75°F) and spinach (45 to 75°F). Perennial vegetables, asparagus, rhubarb and horseradish can also be planted outdoors in March.
When do you plant your vegetable seedlings outdoors? If you are not planning to protect seedlings with cloches or other measures, you need to pay attention to last freeze dates and last frost dates. Last freeze dates are quite variable in time and location, whereas last frost dates are generally accepted as reliable. Several reliable internet sites have this information. (Check the last frost date by zip code or view the USDA Plant Hardiness Zone Map.)