Itinerário técnico
Um guia de cultivo passo a passo, da sementeira à colheita.
Sow direct two or three centimetres deep in rows. Each seed is a cluster containing several seeds, so groups of three or four plants always come up and thinning is compulsory: leave one every ten or fifteen centimetres. Not thinning gives small deformed roots. Soaking the seed for twelve hours improves and evens up germination.
It wants loose, deep, free draining soil at a pH between 6.5 and 7.5, and dislikes acidity. No fresh manure. Compacted soil gives small twisted roots. It tolerates some salinity, which suits it to gardens near the sea.
It grows well between 15 °C and 22 °C and takes moderate heat and light frost. Sowing too early, with a long cold spell below 10 °C, makes the plant bolt without forming a root, which is the classic spring mistake. It adapts to most of western Europe. On the Portuguese coast and in southern Spain use spring and autumn and avoid the peak of summer. Inland in Iberia water more through the dry months. In France and Germany the natural season is spring and summer, sowing once the soil has warmed steadily. In Italy the same rule applies as in the rest of the Mediterranean: spring and autumn in the centre and south, spring and summer in the north.
Do not use fresh manure or strong nitrogen feeding: that gives forked, hairy and tasteless roots. Use a bed that was composted for the previous crop and top up potassium only, with sieved wood ash, which improves sweetness and keeping quality.
Water regularly and consistently. Swinging between drought and heavy watering splits the roots and forms hard white rings inside. Evenly moist soil gives tender sweet roots.
Hoe often and always shallowly, because the roots are short, near the surface and break easily. The best method is to prepare the bed two or three weeks in advance, let the first flush of weeds germinate, remove it and only then sow: that gives you a decisive head start. A thin layer of sieved compost between the rows greatly reduces later work.
Slugs and snails are enemy number one for this crop and can clear a whole sowing in one damp night. Use barriers of ash, eggshell or sawdust around the bed, collect them at night with a torch and fall back on ferric phosphate if needed. Aphids settle in the heart of the plant and are hard to wash out later: apply potassium soap at the first sign and encourage ladybirds and hoverflies with flower strips. Leaf miner draws pale tunnels in the leaf, which are simply removed by hand. Thrips and flea beetle attack mainly in dry warm weather.
Cercospora makes round dark bordered leaf spots in warm humid weather. Rhizoctonia rots the root in waterlogged soil. Boron deficiency, common in chalky and sandy soils, gives a black heart inside the root: prevent it with compost and seaweed. Use a three year rotation away from chard and spinach.
Lift when the root is five to eight centimetres across: at that point it is tender and sweet. Beyond that size it goes fibrous and woody. Twist the leaves off rather than cutting close, because a cut at the crown makes the root bleed and lose colour when cooked. The young leaves eat like chard and are excellent. The reference colour is dark red, and that is what tells you it is ready.
