What to do now
Mildest step first.
- Check the shoulders weekly from about 7 weeks after sowing.
- Lift one test root and cut it; it should be crisp and solid all the way through.
- Water evenly and mulch, so a soaking rain does not follow a dry spell.
- Harvest everything before a hard freeze, and cut tops 2 inches above the crown.
Not sure this is it? Check other korean radish problems
Signs it is ready
Korean radish pushes its green shoulder above the soil as it sizes up. When the shoulder is about 2 to 3 inches across, lift one root and cut it: a ready mu is crisp, white and solid all the way through. Korean types such as Alpine and Summit are listed at about 55 days from sowing; in a fall garden, where days shorten and cool, 55 to 70 days is more typical. Loosen the soil with a garden fork before you pull, so the root does not snap.
It can wait, within limits
Small spring radishes turn pithy within days of maturity, but fall radishes hold much longer. University of Illinois Extension notes that winter types keep high quality for a fairly long time in the garden, especially in cool fall weather, and can keep growing larger. That leaves room to time the harvest for kimchi-making. The limits are heat and hard cold. Utah State University Extension notes that hot weather causes bitterness, stronger heat and hollow roots. At the other end, long stretches below about 30°F can leave roots spongy, so plan to harvest before a hard freeze.
Why roots split
Split roots are mostly about water. Illinois and Utah State point to the same cause: heavy watering or a soaking rain after a dry period makes mature roots swell faster than the skin can stretch, and older roots split more readily than young ones. Water evenly through the season, mulch to hold moisture, and if a big rain is forecast once roots reach size, harvest first. A split root is still good to eat if you use it soon; trim off any cracks that have browned.
Why roots go pithy or hot
A pithy mu is dry and spongy inside, sometimes with a hollow center. The common causes are roots left in the ground too long in warm weather, drought stress while the root is filling, and long exposure to hard cold. A harsh, hot flavor comes from slow growth, heat stress and age, according to Utah State. Sowing on time, about 10 weeks before your first fall frost, steady water, and pulling roots once they reach size prevent most of it.
Storing for winter
Cut the tops about 2 inches above the crown as soon as you pull the roots, because the leaves keep drawing moisture out; the leaves can be blanched and dried as siraegi. Johnny's Selected Seeds says topped Korean and daikon radishes store 6 to 10 weeks at 32°F and 95 percent humidity. Illinois notes that winter radishes pulled before the ground freezes can keep for up to several months in moist, cold storage, such as roots packed in damp sand in a cold cellar or garage that stays above freezing.
Growing it again? When to plant korean radish for your ZIP code
Growing it again? When to plant radish for your ZIP code
- When should I plant napa cabbage and Korean radish for fall kimchi?Sow napa cabbage about 11 weeks before your first fall frost and Korean radish (mu) about 10 weeks before it. Both grow best into cooling fall weather, hold through light frosts, and should be harvested before the first hard freeze.
- Why are my radishes all leaves and no bulb?Radishes that grow all tops are usually too crowded, growing in heat, or getting too much nitrogen. Thin to 1–2 inches apart and sow the next round in cool weather.
- Why are my carrots forked or hairy?Forked carrots usually hit stones, clods, or hard soil. Lots of fine hairs, with yellow, bunchy tops, points to aster yellows. Knobby galls point to root-knot nematodes. Loosen the soil deeply before you sow again.