One of the fastest crops in the garden — small-rooted spring types go from seed to table in as few as 22 days.
Raphanus sativus · also called garden radish, table radish
Windows are counted from the average date of your last spring frost.
Radishes mature so quickly they can fill gaps between slower crops without competing for space. They also act as a trap crop, drawing flea beetles away from neighboring brassicas.
A little history. Native to temperate Asia and cultivated for at least 2,000 years, radish is a cool-season annual that stores energy in a swollen hypocotyl (the stem tissue just below the cotyledons, not a true root) and upper taproot.
Sow seeds ½ inch (13 mm) deep, and aim for 2 inches (5 cm) between plants once thinned. Keep the top half-inch moist until sprouts show; do not let the seedbed crust over or emergence drops sharply. Seedlings emerge in 3–7 days.
Water every 2–3 days in warm weather; daily in hot spells above 75 °F (24 °C). Water when the top inch of soil feels dry to the touch. Aim for about 1 inch per week including rain.
A single pre-sow amendment is usually sufficient; no mid-season feeding needed for quick spring types. What to use: work in balanced compost before sowing; avoid high-nitrogen fertilizers, which push leafy top growth at the expense of root development.
Pinch off any flower stalks the moment they appear to redirect energy back into the root, though a bolting radish is best pulled and composted.
It's ready when shoulder of the root is visible at soil level and measures ¾ to 1 inch across for small types; pull one test root and check for firm, crisp flesh with no sponginess. Grasp the base of the leaves close to the soil and pull straight up with a steady, even pressure. Loosen with a hand fork first in heavy clay. Harvest promptly — roots left in the ground beyond peak size become pithy and hot.
Twist off the tops, leaving ¼ inch of stem; store unwashed in a sealed bag in the refrigerator crisper drawer for up to 2 weeks. Daikon keeps up to 4 weeks the same way.
Sow a short row every 10–14 days from first sowing until temperatures climb above 75 °F (24 °C); resume the same schedule 6 weeks before first fall frost for a continuous supply.
Carrot
Radish sprouts in 3-7 days and marks the row while slow carrot seed is still underground, and it is pulled long before the carrots need the space. The shallow swollen radish sits above the carrot's deeper taproot, so the two rarely fight for water.
Lettuce
Lettuce feeds from a shallow mat of fine roots while radish swells just below it, so a row of radish tucked between lettuce plants uses space and water the lettuce is not reaching. Both are out of the bed within about six weeks.
Spinach
Broad, low spinach leaves shade the soil surface between radish rows, which can keep the seedbed cooler and more evenly moist through late spring — conditions that hold off bolting (the shift from root growth to flowering) a little longer.
Cucumber
Radish leaves often take the first feeding hits from flea beetles and cucumber beetles that would otherwise chew young cucumber seedlings. Treat it as a sacrificial planting: pull and bin the chewed radishes rather than leaving them to breed beetles.
Nasturtium
Aphids often settle on nasturtium stems in preference to radish foliage, which can keep colonies off the crop. It only works if you cut and remove the infested nasturtium shoots before the aphids spread.
Hyssop
Old companion charts have long kept radish away from hyssop, though no mechanism has ever been demonstrated. If you want the pairing separated, do it on practical grounds: hyssop is a woody perennial and radish wants loose, freshly forked ground each season.
Turnip
Turnip is in the same cabbage family as radish, so the two share clubroot, black rot, flea beetles and cabbage root maggot. Growing them side by side concentrates all of that pressure in one patch of soil and makes rotation harder to keep honest.
Watercress
Radish is a mustard-family relative, so it feeds the same flea beetles and hosts the same downy mildew and clubroot. Grown together the pest and disease load stacks, and radish needs free-draining soil that dries between waterings — the opposite of what cress wants.
Give the cabbage family 4 years away from this spot before any of its relatives return.
The tomato family, the pea and bean family or the carrot family thrive in this ground next season.
Radish is a light feeder that leaves the bed loose and open, with little debris to clear. Keep all cabbage-family crops — including turnip, kale and broccoli — out of this ground for 4 years. Follow with tomatoes and peppers, beans or peas, or carrots and parsnips.
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