How to grow Rhubarb in New Zealand

Where to plant

Give rhubarb a permanent spot in full sun with fertile, well-drained soil. It dislikes wet feet, and it struggles in sandy soil unless plenty of compost has been dug in. Plants last for many years, so choose a corner of the vegetable garden where they will not be disturbed.

Rhubarb grows throughout New Zealand. It loves the cold winters of the south, and in the warm north the stalks tend to be thinner.

• Northland to Wellington and Nelson: plant crowns from autumn through winter into spring.
• Canterbury: plant in March or April while the soil is still warm, or from September to November as growth starts.
• Otago, Southland and Central Otago: plant crowns from September to November as the soil warms, and water well through dry Central Otago summers.

Choosing a variety

• Victoria is the most popular variety, with chunky, upright red and green stems on a compact plant.
• Glaskin's Perpetual is early, with slim, bright red stems, and is quick to establish from seed.
• Ruby Tart grows strongly, with ruby red stems and good flavour.
• Winter Harvest gives juicy, sweet, bright red stalks.
• Green-stemmed varieties stay green when ripe; that is normal and they are just as good to eat.

How to plant

1. Dig in plenty of compost and sheep pellets before planting.
2. Plant a crown or division so the tip of the crown, where the leaves emerge, sits just above the soil surface, about 1 m from its neighbours. Buried too deep, it can rot.
3. Water in well and keep the soil moist while it establishes.
4. To divide an old clump, slice through the crown with a sharp spade in autumn or winter, keeping a good bud and roots on each piece, and replant straight away.
5. From seed, sow in trays in spring, pot on, and plant out 1 m apart once seedlings are at least 10 cm tall. Seedlings take a few years to reach full size and can vary from the parent.

Watering and feeding

Keep plants well watered through dry periods for more and juicier stalks. Established plants recover if they dry out, but regular water gives the best crop.

Rhubarb is a hungry plant that likes nitrogen. Feed with a general fertiliser or blood and bone in spring and autumn, and add compost or well-rotted manure around the plants each year, keeping it off the crown.

Pruning and care through the year

• Do not pick any stalks in the first year after planting, and only a few in the second, so the plant can build up strong roots.
• Cut off any flower stalks as soon as they appear, as flowering weakens the plant.
• Keep the area around the plants weed free.
• When the leaves die back in autumn, clear them away so the crown is open to the cold, which helps it shoot well next season.
• Lift and divide clumps every five years or so, when they become crowded and the stalks get thinner.

Harvesting

Pick stalks once they are thick enough to use, before they get old, woody and bitter. Grasp a stalk close to the ground, then twist and pull so it comes away from the crown. Take care not to damage new shoots, and always leave several stalks on the plant so it can keep growing.

Cut off the leaves straight away and compost them; never eat them. Stalks keep for a week or so in the fridge, and freeze well cut into 5 to 10 cm lengths.

Growing in pots

Rhubarb grows happily in a large, deep pot filled with vegetable mix, which also makes it easy to move. Water regularly, as pots dry out faster than garden beds, and feed in spring and autumn.