How to Grow Artichokes in Australia

Globe artichoke (Cynara cardunculus Scolymus Group, family Asteraceae) is a perennial thistle grown for its fat, unopened flower buds. One plant spreads its silver-grey leaves across about 1.5 m and crops for several years in most of Australia outside the tropics. The mistake most growers make is cutting too late, once the bud has started to open and turned tough.

Three mistakes that matter

1. Planting where the soil stays wet. Crowns (the base where stems meet roots) sitting in winter-wet or humid soil are prone to crown rot, the main trouble in many districts. Plant on a mound or raised bed of free-draining soil (see Site, soil and setup).
2. Leaving buds until the scales open. An opening bud turns tough and stringy, with a fuzzy purple centre. Cut while the bud is tight, heavy for its size and still globe-shaped (see Harvesting Buds).
3. Crowding the plants. Mature plants spread 1 to 1.5 m, and crowded plants in damp, shaded corners invite mould and mildew. Give each plant its full space in open sun.

When to plant

Sow in spring once the soil holds about 15 to 18°C. Seed germinates best at 21 to 28°C, so start it in pots in a warm spot or on a seedling heat mat. One sowing is enough, because each plant stays for years.

In frost-free districts an autumn sowing also works.

Site, soil and setup

Artichokes need full sun, shelter from strong wind and a spot they can hold for several years. Plants stand about 1.5 m tall, so put them at the southern end of the patch.

The soil should be deep, rich and free-draining, with a pH of about 6.5 to 7.5. On heavy clay or in summer-rain districts, plant on mounds or a raised bed (see what to do when soil will not drain).

Rotation matters little: artichokes suffer few soil diseases, so divided plants can go back into the same bed once it is enriched.

Sowing Seeds

Raise seedlings in pots, then move them to the permanent bed. Due to quarantine restrictions and our shipping policy, we cannot send artichoke or cardoon seed to Tasmania.

Choosing a variety

Plants raised from seed vary, and a few seedlings come up spinier or with smaller buds than the parent. Raise one or two more than you need and keep the best.

Starting under cover

• Sow two seeds 10 mm deep in each small pot or deep cell of seed-raising mix.
• Keep the mix moist and warm (see When to plant); seedlings usually appear in 8 to 21 days.
• Snip out the weaker seedling at soil level, leaving one per pot.
• From the first true leaves, water with seaweed solution at half strength (15 mL per 9 L) every fortnight.
• Watch for damping off (seedlings collapsing at soil level) in cold, wet mix.

Planting out

Plant seedlings out at 6 to 12 weeks old, after the last frost.

• Harden off seedlings first (accustom them to outdoor sun and wind over about a week).
• Space 'Green Globe' and cardoon 1 to 1.5 m apart, and 'Colorado Red Star' 60 to 90 cm apart.
• Set each plant at the depth it grew in its pot and water it in well.
• Mulch around the plants, keeping the mulch clear of the crown.
• Shield young plants from heat stress and drying winds until they settle.

Pollination

Pollination works in reverse here: you eat the unopened flower head, so a well-picked plant never flowers. Its florets need insects to carry pollen, and bees crowd to any open head.

Artichoke and cardoon are one species and cross freely, and saved seed rarely comes true. Wild artichoke thistle, the same species run wild, is a declared weed in South Australia, Victoria and Tasmania. Its seed blows on feathery tufts.

• Check your state's weed rules before letting any plant flower and set seed.
• If you leave a head for the bees, cut it off as the purple fades, before the fluffy seed forms.
• Put spent heads and old flower arrangements in the general waste, never in bushland, where cut-flower waste has spread the weed.
• Grow new plants from offsets (side shoots with their own roots) of your best plant rather than from saved seed.

Care by growth stage

Big buds come from big plants, so the aim is strong leaf growth first, then potassium as the bud stems rise. Artichokes are heavy feeders and crop poorly in dry soil, although they survive it.

Never let plants wilt while buds are forming. In cool districts, heap mulch around the crowns in autumn to protect them through winter.

If you prefer a conventional feed, mix a controlled release all-purpose granular (NPK around 12-3-8 to 14-5-10) into the soil at planting. Water in an all-purpose soluble (NPK around 23-4-18 to 27-5-9) fortnightly during leafy growth. As bud stems appear, switch to a fruiting and flowering soluble (NPK around 15-4-26 to 15-5-20).

Cutting Back

Cut back after each flush of buds and again as plants die down, so fresh shoots from the crown take over.

• After cutting a bud, shorten its stem by about half to encourage new growth.
• Once stems yellow after harvest, cut them to about 30 cm, or to just above the ground if plants die back in summer.
• In winter, keep the four strongest shoots on each plant and remove the rest.
• Lift and divide clumps every two to three years, leaving at least three shoots on the parent. See dividing perennials.
• Replant offsets about 15 to 20 cm long, trimming off the older leaves and any woody roots first.

Companion planting

Companions fill the gaps while plants are young; keep away crops that get dug or that need the same sun.

Grows well with

• Lettuce, sown in the bare soil around young or newly divided plants as a quick crop before the leaves spread.
• Asparagus and rhubarb, fellow perennials that can share a permanent bed away from annual crops that get dug.

Keep apart

• Potatoes, whose small tubers are hard to clear from a permanent bed once they escape.
• Tomatoes, capsicum and other sun-hungry crops, which a 1.5 m artichoke shades if it stands on their northern side.

Harvesting Buds

Cut each bud when it is full size, heavy for its size and still tightly closed, before the scales loosen or change colour.

• Cut the large bud at the top of each stem first, then the smaller side buds as they size up.
• Expect 'Green Globe' top buds of about 8 to 15 cm across, and 'Colorado Red Star' main buds of 6 to 9 cm.
• Test a bud by squeezing it: a tight, fresh bud squeaks.
• Cut with secateurs or a sharp knife, leaving 2 to 5 cm of stem.
• Pinch off any buds a young 'Green Globe' forms in its first season, so it builds leaves instead.

Refrigerate buds soon after cutting and use them fresh. Even at an ideal 0°C and high humidity, artichokes keep less than three weeks.

Steam or boil whole buds until the outer scales pull away easily, then eat the fleshy scale bases and the heart. Scrape out and discard the hairy choke, and rub cut surfaces with lemon juice to stop them browning.

Cardoon

Cardoon is sown and planted like artichoke but grown for its leaf stalks. Wear gloves to handle it, because its leaves carry spines and can irritate some people's skin.

In late summer or autumn, tie the leaves of a full-grown plant together and wrap it in newspaper or black plastic to exclude light. After about 4 to 5 weeks of this blanching, the stalks turn pale and tender. Cut the plant just below the crown, trim the leaves, and cook the stalks, because cardoon is not eaten raw.

Common problems

No buds in the first year. Seed-grown 'Green Globe' usually spends a full year on leaves, so expect the first buds in its second spring.

Drooping outer leaves. Waterlogged roots in winter or dry soil in a hot summer both cause drooping, and plenty of compost in the soil guards against each.

Small buds. Warm subtropical and tropical climates give smaller heads, and hungry or dry plants do the same.

Plants dying down in summer. Where summers are long and dry, plants often die back after flowering and reshoot in autumn, so cut them back rather than dig them out.

Seed slow to come up. Cold mix is the usual cause, so keep pots warm until seedlings appear (see When to plant). Read more

Bronzed, blistered scales after frost. A light frost blisters and bronzes the outer scales, but the bud beneath is still good to eat.

Pests and diseases

Artichokes have few serious pests, and most trouble lands on young plants and new buds.

Artichoke aphid (Capitophorus elaeagni). This and other aphids cluster on new shoots and buds; hose them off, or spray horticultural oil or soapy water outside hot weather. Read more

Common garden snail (Cornu aspersum). Snails and slugs chew young plants and new shoots in wet weather, so hunt them by torchlight about two hours after sunset. Read more

European earwig (Forficula auricularia). Earwigs chew irregular holes and ragged edges in leaves at night; set rolled cardboard traps and empty them each morning. Read more

Prevention first

• Keep crowns out of wet soil and plants uncrowded, as set out in Three mistakes.
• Clear old stems and leaf litter when cutting back, as snails and earwigs shelter in them by day.
• Pull low weeds and move rock or timber piles away from the bed.
• Welcome ladybirds, which breed on artichoke plants and feed on aphids; see attracting beneficial insects.

Tips

1. For first-season buds on 'Colorado Red Star', plant out early enough that young plants get about 10 days of cool weather, around 7 to 10°C. This vernalisation (a cool spell that triggers flowering) sets buds sooner.
2. Pick the first buds of the season promptly, because early buds tend to be the best quality.
3. Jerusalem artichoke (Helianthus tuberosus) is an unrelated sunflower grown for its tubers, and needs different care.