NDSU Extension - Burke County


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Will It Grow Here?

County Agent News
Dan Folske
February 12, 2018

Will it grow here?

            I started getting seed catalogs before Christmas and they are coming steadily now. They are full of vegetable seeds, fruit trees, bushes and other wonderful garden and landscaping plants. The photos are beautiful and the descriptions sound like they will grow anywhere! The companies which have been around for a while like Gurney’s, Burpee’s, Johnny’s Selected Seeds, and others are generally pretty good about providing zone recommendations but others may not be.

            What are “zone recommendations”?  The US Department of Agriculture has divided North America into 13 different hardiness zones for plant survival.  The 2012 USDA Plant Hardiness Zone Map is the standard by which gardeners and growers can determine which plants are most likely to thrive at a location. The map is based on the average annual minimum winter temperature, divided into 10-degree F zones. While these zone recommendations are most applicable to perennial plants like grasses, trees, and shrubs, they are sometimes used as indicators for annuals too because they often reflect summer growing conditions to some extent.  However, there are other guidelines like Growing Degree Days (GDD’s), days to maturity, and minimum frost free days which are better suited to annuals.

There are also a few vegetables which you may see listed as short day, long day, day neutral, or intermediate. Onions form bulbs in response to daylength. When the Veggiesnumber of daylight hours reaches a certain level, onion plants start bulbing, or forming bulbs. Long-day onions need about 14 to 15 hours of daylight to bulb. Short-day onions need 10 hours of daylight. These descriptions apply primarily to onions can apply to some other plants as well. Short day onions grow best in the southern United States where they receive 10 to 12 hours of daylight during the summer months. They are planted in the fall or in early spring and grow vegetatively until the day length triggers bulb growth. If you plant a short day onion variety here it will grow and develop but you will never get really large onions because the plant does not get enough top and root development before it begins bulb production. A long day variety will have a longer period of plant development before it begins to bulb. Early planting is a key for any type of onion. The better the plant development before bulbing, the larger the bulb. We do have an advantage here. We can grow any type of onion, a short day onion just won’t produce as well as it would farther south. If a grower in Texas planted a long day onion. It would never get the day length it needed to trigger bulb development.

Next week I will explain more about GDD’s and days to maturity.

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