Growing Radishes from Seed
Quick to germinate, radish seeds stay viable for several years and are used for succession planting with other crops to mark rows.
Botanical Names: Raphanus sativus
Growing radishes from seed is like magic: throw the seeds onto the ground and cover with barely half an inch of soil, then water and watch them grow. Radishes are always grown from seed directly into the soil where they will grow to maturity and do not need to be started indoors and then transplanted.
Taking only four or five days to germinate and show their first green growth, radishes seeds are often mixed with the seeds of that germinate much more slowly – carrots and beets, for instance – in order to mark the rows. Since the radish seeds will germinate in just a few days it’s easy to see where the slower germinating seeds will eventually come up. That way you won’t accidentally dig them up when weeding.
Once the radishes have gained full size they are harvested, leaving plenty of room then for the beets or carrots to spread out as they grow.
Radish seed facts: seed packets usually contain 250 to 500 seeds apiece. A ½ ounce of seed is enough to produce a 100 foot long row of mature radishes. Radish seed can stay viable for up to four years if kept in cool, dark conditions. And usually 75 percent of seeds in a packet will germinate.
To be successful in planting and growing radish seeds, pay special attention to several factors. For the most part radish seed growth is best when they are planted in cool soil; early spring or fall are the preferred seasons for many varieties. Next, be sure to get the soil in good shape before planting – loose, full of seasoned organic material, but not overly fertile.
Moisture and soil depth must be right, too. Planting radishes from seed works best if the soil is moist but does not have standing water; healthy plants will resist pests and diseases more readily. As for depth, radish seed is sown very close to the surface, about ½ inch deep. Some experts recommend sprinkling the dirt on top of the seeds rather than trying to bury the seeds; that way they may be too deep.
Radish plants must be thinned fairly often once the tops have reached a height of an inch or two.That practice allows enough room for the roots to grow round and firm.
Some gardeners like to gather their own seed for use the next year. If that is the case, be sure to grow only one radish variety in the garden, so that different radishes don’t cross-pollinate and lose their distinctive characteristics.
To collect seed, let the radishes grow flowers. Those will mature into seed pods. Stake up the stems so they don’t fall over and burst. As seed heads mature, cover them with lightweight cloth bags so that birds don’t eat all the seeds. When the seed pods dry, bring indoors and store in a dry place until the next growing season.