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How to troubleshoot problems growing carrots and cabbages
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April 27, 2012
CORVALLIS, Ore. – Often gardeners look back at last season's crops and feel that they grew less-than-perfect vegetables.
Two common challenges are “hairy” or misshapen carrots and poorly formed cabbage heads. Jim Myers, an Oregon State University vegetable breeder, said there are a few things gardeners can do to overcome the challenges next season.
"Hairy or misshapen carrots or carrots with multiple roots twisted around each other may come from spacing, soil type, pests and disease,” Myers said. “It helps to thin them to an inch apart after the leaves reach up about three inches.”
Heavy clay soil may force carrot roots to grow crooked. Amend clay soil in next year’s carrot patch with leaves that are well broken down and compost that is well-rotted. Carrots do well in light (sandy) soil that is not full of amendments.
Root-knot nematodes may cause deformed carrots and can be verified with a soil test. You might have to solarize (treat soil with the sun’s heat using plastic sheeting in the summer) or rotate your carrots to another area next time.
Another potential cause, Myers said, is recent fertilization – or over-fertilization.
"Excess nitrogen can cause carrots to form multiple roots or get hairy,” he said. “If you add manure-laden compost to your soil, do so in the fall, then let it overwinter before planting carrots in the spring. Carrot roots also will get hairy in waterlogged ground.”
Growing good cabbage with well-formed heads is often a challenge. Some cabbages don't set heads and sometimes those that do crack open. You might be watering too much.
Excess irrigation after a period of drought (little or no watering) can cause the heads to swell until they crack. Cabbages also crack when they are mature. Try watering them less and harvesting them earlier. Poor heading in cabbage can be caused by several factors, including:
- Overcrowding. Thin your plants early in the season to at least 18 inches apart.
- Under-watering. Is your soil too dry? Are you watering deeply enough? Long infrequent watering is better than shorter surface watering for cabbage.
- Hot weather. If the cabbage is setting a head during a hot spell, the head can be stunted or misshapen. Adequate watering may overcome some of the effects of heat.
- Club root fungal infection. Do your plants wilt during midday after having just been watered? Pull up one of your stunted plants and examine the roots. If they look “clubby” with large swellings, avoid planting any of the brassica family in that spot again. The pathogen may persist in the soil for 10 or more years.
- Root rot fungal infection. In clay soils, or soils with too much water, root rot infection thrives, killing much of a plant’s root system. Rotate this area of the garden to another type of plant.
Source: Jim Myers