How Do I Know When My Radishes Are Ready to Harvest?

Radish has one of the shortest harvest windows of any vegetable — typically a few days to a week between "just right" and "past it." Missing that window means pithy, hollow or excessively hot roots. Knowing how to check readiness, and developing the habit of checking every day once the harvest period approaches, is the most important skill in radish growing.

Days from sowing to harvest

Most standard round spring radish varieties mature in three to four weeks from sowing under good conditions. In cool spring weather (12–15°C), it may take four to five weeks; in warm conditions (18–22°C) it may be three weeks. The seed packet "days to maturity" figure is a useful starting point — begin checking from around three-quarters of that figure rather than waiting for the full stated time.

The soil-surface check

The most reliable field check is to scrape away a little soil from around the top of the root and look at the root diameter. For round types, a root that protrudes visibly above the soil surface and is at least 2–3 cm across (golf ball size or approaching it) is ready to sample. For longer varieties, the root shoulders pushing up at the soil surface indicate approaching maturity. The visual check through the soil takes two seconds and tells you whether to wait or harvest immediately.

Pull one and taste test

The definitive test is to pull one radish and cut it in half. The flesh should be firm, white and crisp with no hollows or sponginess. The flavour should be peppery but not overwhelmingly hot. If flesh is solid and bite is pleasant, harvest the whole row. If the root is still small or the flesh feels very firm and dense with no "give" when cut — more like a wooden bead than a crisp vegetable — give it another two to three days.

Harvest before bolting

Once radish begins to bolt — sending up a flower stalk — the root quality deteriorates rapidly and does not recover. If you see a central stem elongating from the rosette of leaves, harvest everything immediately regardless of size. Small roots harvested before bolting are far better than larger ones left past it.