Saturday, March 9, 2013

Countdown to the Equinox

Our special guests on "Garden Talk" this morning were Lisa Stanley of Stanley's Greenhouses, and UT student David Pease. We had a great discussion about our Plant of the Week, Magnolia stellata, the star magnolia and its cultivars and hybrids. David also shared insights about sweetshrub, or Carolina allspice, Calycanthus floridus and its hybrid and cultivated forms. Either of these shrubs would be a welcome addition to the landscape, and both reach about the same size, typically around twelve feet in diameter.

Tomorrow we switch to Daylight Savings Time, and it is only ten more days until the vernal equinox, March 20. Spring gardening tasks will become ever more numerous as the days lengthen and temperatures warm.

Now is just about the last opportunity to plant asparagus this year. Look for one-year old roots in your favorite independent garden center. Old timers will remember the cultivar 'Martha Washington' as the standard, but plant breeders have improved on this old standby. A more modern asparagus variety is 'Jersey Giant.' Seeds of this strain of asparagus produce 95% male offspring. Male asparagus plants are more productive than females because they do not invest energy in flower and seed production. The absence of seeds also means that volunteer seedlings, typically of inferior quality, will not crowd out your original planting.

Asparagus needs rich soil high in organic matter. A shovelful of well-composted manure (you can buy this in bags at many garden centers) should be placed beneath each crown you set in the bed. Dig down about five inches, add the compost, and place the crown on top, spreading the roots out as much as possible. Take care not to damage any developing shoots. Cover the plants with a layer of garden soil and water in well. Two weeks later, add another inch of soil. Continue adding more soil over the next few weeks until the planting site is slightly mounded. Keep the plants well watered and side dress with compost tea or a balanced organic fertilizer. Mulch to control weeds and remove any that do appear.

The key to success with asparagus lies in the treatment it receives during the first two years. Irrigation will be necessary to keep the plants growing well when rainfall fails, and each spring and fall the plants should be side dressed with a balanced organic fertilizer. Do not harvest any spears during the first growing season, and harvest sparingly during the second. Thereafter, the plants will be well-established and you can harvest at will.

Leave the foliage in place until late winter, then remove and burn or discard it to help control insects that may overwinter in the dead foliage.

A caller from Lee County, Virginia, this morning asked about growing vegetables in very rocky conditions. We suggested placing large containers here and there among the boulders and growing veggies in these, rather than trying to remove all the stones from a large plot. Container vegetable growing is a great way to utilize space that you might not otherwise consider for food crops. Always use a good potting mix, water regularly and choose plant varieties that remain small enough or adapt well to containers. Some of the best choices for container growing are lettuces and other greens, radishes, tomatoes, peppers, and bush beans. With the addition of a trellis, you can also grow peas and cucumbers in container gardens.

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