We are fortunate in Kansas to have distinct seasons for our gardens! Spring is one season for planting cole crops.
“Cole crops” is a general term used to describe several vegetables in the mustard family, including broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, and kohlrabi. All cole crops are cultivated varieties of the species Brassica oleracea.
If you planted cole crops such as cabbage, broccoli and cauliflower earlier this spring and made it through our earlier cold snaps, they will need a little fertilizer boost. These plants need to mature before summer heat arrives, so they must grow quickly while the weather is cool. A sidedressing of fertilizer about three weeks after transplanting helps plants continue to grow rapidly.
Use fertilizers high in nitrogen for sidedressing such as nitrate of soda or blood meal at the rate of 2 pounds per 100 feet of row. You may also use lawn fertilizers that have close to 30% nitrogen such as a 30-3-4 or 29-5-4 but the rate should be cut in half to 1 pound per 100 feet of row. Do not use lawn fertilizers that have weed killers or preventers. Fertilizer must be watered in if timely rains don't do that job for you.
We have a sheet available that gives recommendations on how to sidedress specific vegetable crops. It can be found at https://tinyurl.com/j2ggaa6.
— Scott Eckert is a Kansas State Research and Extension agent for Harvey County. Horticulture is his specialty.