February 12, 2015

How to Grow Radishes 

Radishes are the first crop to find a home in my garden every spring, a fact that always surprises me because for many years, I was an unwavering “radish hater.” Until I turned 30, the only radishes I had ever tried were the shredded ones you sometimes find at salad bars. I still don’t like those radishes very much, but I can say without a second thought that homegrown radishes have become a favorite in my house. Their taste is a far cry from those shredded pieces of pith at the salad bar, and if you, too, consider yourself an unwavering “radish hater,” promise me you’ll try again. As with most vegetables, the only way to get a true taste is to grow your own.

Cool-Season Gardening

Radishes are a cool-season crop, meaning they prefer to grow in the cooler temperatures of spring and fall. They grow best in temperatures between 50 and 70 degrees F. Radishes will bolt (or flower) when the days begin to lengthen in late spring and the temperatures get warmer. If the plants begin to flower before the root has formed, no root will develop, or if the plant is gearing up to flower, it puts its energy into making the flower instead of fattening up the root. What this means is the earlier you plant your radishes, the better. I begin to sow radish seeds in my USDA zone 6 garden in mid- to late March.

Radishes tolerate frosts quite well, so you can sow your seeds about four to six weeks before your last expected frost. Harvests begin anywhere from 20 to 40 days after planting, depending on the variety. The tastiest harvests occur when the roots are quarter-sized. Waiting too long to harvest will result in woody, pithy roots. To stagger my harvest, I sow a handful of seeds every week or two through the spring up until early June. I also plant a fall crop in late summer.

Find Soil Balance

Another thing to keep in mind for good radish production is that root vegetables of all sorts need phosphorus to develop good roots. If your soil is deficient in phosphorus, work some bone meal or rock phosphate into the area in the fall. It will be readily available come spring.

Soil pH can also be a factor when growing radish. Because phosphorus becomes tied-up and unavailable for plant use at lower pH levels, it’s important to maintain an average soil pH of around 6.5 in the vegetable garden in order to enable the plants access to plenty of phosphorous. At this pH, the greatest variety of nutrients is available for plant use.

Having too much nitrogen in the soil is another no-no for radishes and other root crops. Nitrogen makes lots of green growth, which is not what you want, so skip the nitrogen fertilizers in the vegetable garden and turn to compost, aged manures and leaf compost instead to feed your garden a more balanced diet.

Pest Control

The only trouble I sometimes face in growing radishes are the little holes I find in the foliage. They are a clear sign of flea beetles, a common radish pest. To deter them, I cover my newly planted radish seeds with floating row covers. These lightweight, white fabric covers rest on the plant tops and create a physical barrier to all kinds of pests. If the row covers don’t work and the flea beetle pressure is extreme, I sometimes turn to neem oil or spinosad-based organic pesticides, but they are seldom needed, as radishes can outgrow almost anything.

Make these radish recipes from HobbyFarms.com:

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