University of Vermont Extension 
Department of Plant and Soil Science

Spring News Article

Charlie Nardozzi, Horticulturist and
Leonard Perry, UVM Extension Horticulturist
Keeping cyclamen in flower indoors, spraying horticultural oil outdoors, and building a cold frame are some of the gardening activities for this month.
Cyclamen are beautiful houseplants that can flower for weeks indoors this time of year, but they are subject to some problems. Spider mites love them and may force you to spray plants with insecticidal soap. Cyclamen can be cut back to the soil line and they will resprout new shoots in no time. Also, overwatering causes root rot, which can spell death.  Ideally they prefer, and stay in bloom the longest with, cool conditions (55 to 65 degrees F) and even watering.
Spray horticultural oil on fruit trees such as apples, plums, and cherries, to smother any overwintering insects.  These are often called “dormant oils” as they’re applied while trees are still dormant, just before buds emerge. Choose a calm day when temperatures are above 40 degrees (F), and when no rain is forecast.  Be sure to cover all sides of branches, including inner and upper ones. Carefully follow the label instructions for proper usage and appropriate plants.
You can make a simple cold frame by placing hay bales along the perimeter of a rectangle, and placing old windows or a glass storm door over the top. Purchased cold frames are convenient, and some have thermostatically-controlled tops that open automatically when the temperature inside hits a designated point. Since the midday sun can heat this space up quickly, such a vent is especially handy if you're away for long stretches during the day.  Check seed catalogs and online garden suppliers for many types and price ranges of cold frames.
Cole crops such as broccoli, cauliflower, and cabbage, can be started over the next couple of weeks indoors under lights. These cool-loving crops will grow six weeks indoors before being transplanted outdoors (generally early to mid-May in the North Country) two weeks before your last “average” frost date.  Keep seedlings moist and well fed to get the sturdiest transplants.  Lanky, tall seedlings will be a sign they’re getting too much fertilizer, too little light, or both.  If you don’t have a cold frame, you may want to set mature seedlings outside when not freezing so they’ll “harden off” and get stockier.
When planning your vegetable garden layout, avoid planting members of the same plant family in the same spot they were in last year, or even the year before. Members of the same family are susceptible to the same diseases and insect infestations. For example, avoid planting members of the tomato family (tomatoes, potatoes, peppers, and eggplant) in the same place year after year.  You may rotate these crops with other families such as the legumes (beans, peas), cabbage (cabbage, kale, radishes, turnips), or the cucurbits (cucumber, melons, squash).
Check strawberry plants twice a week for signs of new growth. As soon as you see sprouts, remove the straw mulch and spread it in the rows to help control weeds. A topdressing of an inch or two of compost will give plants a boost.
If you’re growing raspberries, spring is the time to prune shoots before new growth begins, if you didn’t last year.  If growing the “everbearing” or two-crop types such as ‘Heritage’ or ‘Fall Gold’ for just a fall crop, you can prune all shoots to the ground.  Summer-bearing types produce fruit on canes from last year, so don’t prune these out or you won’t have any fruit.  Prune out canes that fruited last year, usually those more woody, light in color, and brittle.  For any type, prune out canes that are weak and spindly, leaving healthy ones 6-inches or so apart.
(Charlie Nardozzi is a nationally known horticulturist, author, gardening consultant, and garden coach; 

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