Radishes are a wonderful spring crop! They germinate within a week and mature 3-4 weeks later. They are not too fussy about soil, but if yours is quite heavy, you may want to add a few inches of organic matter to the top 3 inches. They will germinate in soil that is between 45 and 85 degrees. Make a little trench 1/2 to 1 1/2 inches deep. If your soil is heavy, plant them on theshallow side. If your soil is sandy and the weather is quite warm, plant them on the deeper side. Space them 2-4″ apart. If your soil is fertile, they can be grown closer together.
Thinning is essential or they will not produce good roots. I always tend to plant them thicker than I should and have a hard time thinning them. I don’t like to throw away good plants. But you can eat the thinnings in salad. Experience has taught me that radishes grown too close together, do not produce good roots. They MUSt be 2-4″ apart at the least. I like to plant several rows about 6″ apart. Radishes will not produce a nice swollen root if they do not have enough space. For this reason, you must also keep the weeds out of your radish rows. After they are a few inches tall, I like to mulch them with chopped leaves or grass clippings. This is more important in the summer as it will keep the soil cooler and hold moisture and helps keep the weeds from growing.
Radishes can get strong and pithy when they do not get enough water, especially in the heat of summer. So they are best grown in spring and fall. It is very easy to plant several rows two weeks apart to extend your harvest. To harvest them, push a little dirt away from the base of the radish so you have an idea of its size. If it looks large enough, simply pull the plant by hand and wash the roots and trim. Radishes will keep several weeks in a plastic bag in the refrigerator.
It is easy to save seed from radishes. Simply let some of them grow in the garden. IN due time, they will flower and produce seed pods. Leave them on the plant until they are mostly dry. I pick off the spray of seed pods and put them in a paper bag in a dry place. After they are completely dry, crush the seed pods and strain out the seeds. It is ok if you have a little chaff in with the seed. Store them in a cool dry place so you can plant next year. Of cours, you must start with heirloom, open-pollinated seed so you can be sure your seed will produce true to type. Also, be sure that the plants you let go to seed have large roots. You do not want to propagate radish plants that did not have well-developed roots on them.