Archive for April 2, 2008

Cool annuals


                                   By Master Gardener Carolann Sears

            For gardeners anxious to get out into their gardens, early spring is the time to plant cool weather annuals.  After a hardening-off period, and as soon as the soil can be worked, there are a large number of annuals that can be bought and planted as early as April.

            A bed of smiling pansy faces next to an entry way door can lift your spirits on a cool spring day.  Purple and yellow violas planted in beds with tulips or daffodils contrast beautifully and bring color into your garden through May.

            Stocks and Dianthus are especially fragrant mixed with containers of Osteospermum (African Daisy) and will brighten up your deck or patio.  Some varieties, like the symphony and soprano series of Osterspermum, have been developed to be more heat-tolerant and will continue to bloom throughout the summer here in Iowa.

            Check with your nursery or green house to see if they have “hardened-off” the plants they have in stock.  Even plants that love cool weather need to be planted with care and some forethought.  They have been raised in a warm green house, without winds, and have been subjected only to filtered sunlight.  Your goal is to increase exposure to wind, sun and drought-gradually.

            Don’t put your new plants into the ground immediately.  Give them an adjustment period of about a week in a sheltered area, out of the wind and direct sunlight, perhaps next to the house.  Watch the weather, and if it’s expected to drop below freezing, keep them in an unheated garage overnight.  Although a light snow won’t hurt them if they are in the ground, cover them as you would in the fall, to keep them from freezing.

            Prepare your planting bed, amending the soil with organic material if it is too sandy or has heavy clay.  Soil that is ready to be worked will hold together loosely when squeezed lightly.  Dig a hole wider than the pot your plants come in, loosening up the soil, and replant your annuals at the same level they were in the container when purchased.  For container gardens, use lightweight, well-drained potting soil or a soilless mix.  Annuals prefer to be watered deeply, but infrequently, needing about an inch of moisture per week.  Water in the mornings, so foliage will dry before nightfall.  Fertilize lightly once or twice during the spring growing season, keeping in mind too much fertilizer may encourage foliage, but inhibit flowering.

            Most cool weather annuals will bolt (flower and decline) during Iowa’s hot humid summers, so plant them with perennials or other annuals that will bloom throughout the summer.  The cool weather annuals may surprise you and bloom again in fall.         

            For more information on annuals, I would recommend a publication available through Iowa State Extension titled Annuals (PM 1942).  It is one of a series of beautiful color publications that not only classifies annuals for use as cut flowers, shade, and drought tolerance, etc., but features color photographs with clear descriptions.

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