Raphanus sativus.

A radish that fixes the most annoying flaw in its family. The classic radish problem is that it goes hollow and cottony as soon as you leave it a few days too long in the ground, and the perfect harvest window is sometimes counted in days. Purple Plum was selected precisely for that: it keeps its firm, crunchy flesh noticeably longer than most round varieties, which forgives a weekend away or a harvest spread over two weeks.

Round, regular roots with luminous purple skin, almost plum-violet, which owes its colour to anthocyanins — the same pigments as red cabbage and beet. The flesh is pure white, and the contrast is what makes the effect: sliced into rounds, the radish draws a purple ring around a clean white heart. The flavour is mild and lightly sweet, with a present but moderate heat, far less aggressive than a black radish or a daikon. Excellent raw in rounds on buttered bread with fleur de sel in the French style, in a crudité platter where it does the visual work, in quick pickles with rice vinegar, or sliced thin on a mandoline into a salad. The tops, often wrongly thrown away, make an excellent cream soup or a pesto.

Grower's tip: the radish is probably the fastest vegetable in the garden, which makes it the best one for a first garden or for children. Two mistakes spoil it, always the same ones. The first: too much nitrogen. Soil that's too rich gives magnificent foliage and tiny roots. The second: heat. Sown in July, the radish bolts and turns hot enough to be inedible. The strategy that works in Québec is to sow early, as soon as the soil can be worked, in successive rows every 10 days until mid-June, then start again in mid-August for a fall harvest — often the best of the year.

• Open-pollinated. Annual. Insect-pollinated; crosses with other nearby radishes — isolate for seed saving.
• Grows in ~30 days.
• Resists going hollow and cottony longer than most round radishes.
• Exposure: full sun, part shade accepted in summer.
• Loose, stone-free, moderately rich soil. Avoid excess nitrogen. Thin to 5 cm.
• Direct-sow as soon as the soil can be worked, in successive rows every 10 days. Start again in mid-August for fall.