By Melanie Mathieson
The Gardening Guru
The radish is a cool-season, fast-maturing, easy-to-grow vegetable and one of the first crops from the vegetable garden each year.
Radishes grow well in almost any soil that is prepared well, fertilized before planting, and has adequate moisture maintained throughout the growing season.
Slow development, usually caused by hot, dry weather, makes radishes hot in taste and woody in texture.
Radishes mature rapidly under favourable conditions and should be checked often for approaching maturity. Harvest should begin as soon as the roots reach edible size and crops should be depleted quickly before the summer heat, which can cause pithiness (woody texture) or seed stalks (known as bolting) to develop.
Spring radishes should be planted as early as the soil can be worked until mid-spring. Make successive plantings of short rows every 10-14 days.
If you are tight on space for successive plantings, plant in spaces between slow-maturing vegetables (such as broccoli, cabbage, or corn) or in areas that will be used later for warm-season crops (i.e., peppers, tomatoes, and squash).
Later-maturing varieties of radishes (Icicle or French Breakfast) usually withstand heat better than the early-maturing ones, and are recommended for late-spring planting for summer harvest.
Winter radishes require a much longer time to mature than spring ones, and are planted at the same time as late turnips (usually mid-summer to late summer) and then left in the garden over the winter.
Sow radish seeds one-quarter to one-half inch deep. Thin spring varieties to one-half to one inch between plants (winter radishes must be thinned to two-four inches, or even farther apart, to allow for proper development of their larger roots).
On wide row beds, radishes may be broadcast lightly and thinned to stand two-three inches apart in all directions.
Pull radishes when they are of usable size (usually starting when the roots are less than one inch in diameter) and relatively young. Radishes remain in edible condition for only a short time before they become pithy (spongy) and hot.
Proper thinning focuses the harvest and avoids disappointing stragglers that have taken too long to develop. Pulling ready-to-eat plants randomly across the bed, meanwhile, will help to allow adequate space for remaining seedlings to develop.
Winter varieties mature more slowly and should be harvested when considerably larger in size. Once they reach maturity, they maintain their high quality for a fairly long time in the garden, especially in cool fall weather.
Size continues to increase under favourable fall conditions. The Daikon or Chinese radish, for instance, can achieve a particularly large size and still maintain excellent quality.
Winter radishes can be pulled before the ground freezes and stored in moist cold storage for up to several months.
You may find that you have root maggots that tunnel into your radishes if you leave them in the garden too long. These tend to be more apparent in wetter conditions.
You can apply a soil insecticide in the spring before you plant if you find that the maggots are a big problem.
What causes my radishes to crack and split? They are too old. Pull them when they are younger and smaller.
A flush of moisture after a period of relative dryness also may cause mature roots to burst and split. Try to avoid uneven moisture conditions in your garden.
Why do my radishes grow all tops with no root development? There may be several reasons:
•seed planted too thickly and plants not thinned (although some roots along the outside of the row usually develop fairly well even under extreme crowding);
•weather too hot for the spring varieties that do best in cool temperatures (i.e., planted too late or unseasonable weather); and/or
•too much shade (must be really severe to completely discourage root enlargement).
What causes my radishes to be too “hot”? The “hotness” of radishes results from the length of time they have grown and in what growing conditions they have developed.
Hot radishes either grew too slowly or are too old. Weather conditions that are hot and dry tend to produce vegetables with a hotter taste, as well.
The sharp or pungent taste in most radishes comes from the skin. If the taste is too harsh for your buds, you might want to peel them.
Recommended varieties to try:
•Burpee White—25 days to harvest, round, smooth white skin;
•Champion—28 days, large, round, red;
•Cherry Belle—22 days, round, red (I’ve had the best success with this variety);
•Early Scarlet Globe—23 days, globe-shaped, small taproot, bright red; and
•Easter Egg—25 days, large, and oval, color mix includes reddish purple, lavender, pink, rose, scarlet, and white (I have suggested these before for growing for children)
•French Breakfast—23 days, oblong red with white tip); and
•Icicle—25 days, long, slim, tapered white
•Chinese White—60 days, large, long, square-shouldered, blunt-tipped, creamy white roots; and
•Round Black Spanish—55 days, rough, black skin, white flesh (recently noted to have cancer-fighting properties)