Watering and Feeding White Icicle Radish: Even Moisture Keeps White Radish Roots from Splitting or Going Hollow

Splitting is a water problem

A long white root that gets a sudden soaking after drying out swells inside faster than the skin can stretch, and it splits lengthwise. Round radishes do this too, but on a long root the crack runs the whole length. The rule is to never let the soil dry right out and to water little and often rather than in floods.

Japanese growers also warn that overwatering is just as bad: soil that stays saturated rots the root and, at sowing time, rots the seed. Aim for the middle: never bone dry, never soggy.

1. Water when the surface dries, enough to reach 6 in When the top of the soil looks pale, give enough to wet the root zone 6 in (15 cm) down, roughly one watering can per square yard in a bed. Judge by feel instead of watering a little every day.
2. Water in the morning In cool weather, water early so the surface has settled by evening. Evening watering chills the soil overnight and slows an already slow late-fall crop.
3. Adjust around rain If heavy rain is forecast, skip the watering before it. Rain hitting dry soil is the classic split scenario; a light pre-watering narrows the swing.

Watering a garden bed

For a fall sowing in a mild climate: water daily until sprouts show, every two to three days while the seed leaves and first true leaves develop, then about twice a week by feel as the plants fill out. A bed under the eaves may never see rain, so after a rainy day check with a finger that the soil in the bed is actually damp.

Do not count a rainy day as a watering for a bed under an overhang. Dig a finger 1 in (2 cm) down; if it is dry, water.

Watering containers

Pots dry faster than beds yet also hold water at the bottom. Water until it runs from the drainage holes and always empty the saucer. In a deep planter the surface can be dry while the bottom is still wet, so push a chopstick in, pull it out and look at the lower half before deciding.

1. Through-water, then empty the saucer Water until it drains, then tip the saucer out. A long radish root reaches near the bottom, and a tip sitting in standing water rots.
2. Do not judge by the surface An 8 in (20 cm) planter is often dry on top and wet below. Check moisture 4 in (10 cm) down with a chopstick before watering to avoid overdoing it.
3. Recheck on windy days Balconies dry out fast in dry wind. On such days, water in the morning and look again in the evening, topping up if the mix has gone dry.

One feeding, after the second thinning

A crop that is pulled after about a month needs little beyond what was mixed into the soil. The standard is one pinch of balanced fertilizer per plant, scattered around it and hilled in right after the second thinning. Too much nitrogen grows lush tops over a skinny root and invites aphids.

1. Same day as the final thinning When you thin to 2 to 2.5 in at four or five leaves, scatter balanced fertilizer at about 1 oz per square yard (30 g per square meter) between plants, not touching the stems.
2. Liquid feed: weekly, twice at most In containers, a liquid feed at label strength once a week, two times, is plenty. Stop feeding a week before harvest.
3. Read the leaves Dark green, thick leaves mean enough. Small yellowing leaves mean too little; huge leaves hiding the root mean too much. If overfed, ease off water so growth shifts to the root.

Hill soil over the shoulders

As a long radish fattens, its shoulders push up out of the ground. Shoulders in sunlight turn green, dry out and crack. Pull soil up to the crown twice, once after the second thinning and again when the shoulders first show. Do not bury the leaf bases; just cover the white.

1. Scrape soil in with your fingers Draw soil from the bed edges up to each crown until the shoulder disappears, stopping below where the leaves attach.
2. Firm wobbly plants Wind-rocked plants open a gap around the root that dries it out. While hilling, press the crown lightly to stop it swaying.

Late-fall care

As temperatures fall, growth slows and the soil dries more slowly. Stretch watering to about once a week and water late morning on frosty mornings. When frost is forecast, a floating row cover protects the leaves and buys another week or two of harvest.