University of Vermont
Department of Plant and Soil Science
SOWING FLOWER SEEDS AND OTHER MARCH
Leonard Perry, UVM Extension Horticulturist
and Charlie Nardozzi, Horticulturist
Sowing seeds of some flowers and vegetables, pruning, and checking
perennials for soil heaving are some of the gardening activities for this
Sow slow-growing flowers such as pansies, begonias, and vinca early in the
month. Sow verbena, petunias, geranium, and impatiens later in the
month. But wait until April to sow seeds for tomatoes, peppers,
eggplants, and most flower varieties that cannot be transplanted until the
danger of frost is past. Cabbage, broccoli, and other cole crops that
can be set out in early spring all can be started this month. Check on
the seed packet to see if seeds can be started indoors, or should be sown
directly in the ground when the weather warms up.
Ideal growing conditions for starting plants from seeds include temperatures
of 70 degrees (F) for germination, then 60 to 70 degrees for good seedling
growth. A seedling heat mat under the flats helps to maintain a proper
To keep seedlings from getting spindly, use high light intensity, as in a
south-facing sunny window. Even there, rotate seed flats every couple
of days so they don’t grow sideways toward the light (i.e.
“phototropism”). For even light, many use a seed germination light
stand you can buy from garden stores or online. Or you can use shop
lights, with balanced spectrum tubes (cool white work fine too), hung six to
eight inches above the seedlings. Newer slimmer tubes (such as T8) are
more efficient. Hang them on chains so you can move them up as seedlings
grow. Use a timer (as found in hardware stores) to keep lights on 14
to 16 hours a day.
March is the perfect time to prune fruit trees, most ornamental trees, and
summer-flowering shrubs. Wait to prune spring-flowering shrubs until
right after bloom, or you’ll cut off their flower buds for this year.
Wait to prune maples and birches until after they leaf out, otherwise their
rising sap will run or "bleed" from open wounds.
Sharpen pruners if they are dull, using a sharpening file from hardware
stores or online. Remember the 2 C’s and 3 D’s—remove any crossed and
crowded branches. Thinning opens up a tree canopy for more air and
sunlight, which gives better growth and less disease. Also remove any dead,
diseased, or damaged branches. Cut broken branches back to a main
branch or the trunk rather than leaving stubs. Wound sealer isn't necessary,
as it may seal in moisture and bacteria which lead to rots.
Take a walk around your yard to check for perennials that may have heaved
out of the ground, exposing their roots to drying winds. Gently tamp them
back into the soil or, if the soil is too frozen, surround them with mulch
as protection, tamping down later.
If you potted some bulbs last fall, and they’ve been in a cool space over
winter, bring them into warmth now to “force” into bloom. Or simply
buy some potted or cut tulips and daffodils to bring spring indoors
early. There are many other flowering potted plants to choose from
during the Easter season including, in addition to the Easter lily,
primroses, azaleas, cineraria, and more. Shamrock plants are available for
St. Patrick’s Day. These members of the Oxalis family are easy to
grow, and prefer a sunny location with even watering.
Other garden activities for this month include attending flower shows and
garden lectures, visiting a maple sugar house, and cleaning existing (or
adding new) bluebird houses.
(Charlie Nardozzi is a nationally
known horticulturist, author, gardening consultant, and garden coach;
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