How to Grow Rocket in Australia

Rocket is the shared name of two peppery salad plants in the cabbage family, Brassicaceae. They are salad rocket (Eruca sativa), a fast annual, and wild rocket (Diplotaxis tenuifolia), a short-lived perennial. Both give leaves within weeks in the cool months, and the usual mistake is sowing into heat, which sends them to flower.

Three mistakes that matter

1. Sowing into hot weather. Rocket is a cool-season crop, and heat sends it to flower fast, after which salad rocket turns hot and bitter. Sow in the months given in When to plant, and shade late spring sowings from the afternoon sun.
2. Sowing one big patch. A single large sowing crops all at once, then bolts (runs to flower and seed) before it is eaten. Sow a short row or a pot every two to three weeks instead, and pick the leaves while they are young.
3. Letting the soil dry out. Dry ground, together with heat, makes the leaves harshly peppery and pushes plants to flower. Keep the soil evenly moist from sowing to the last pick, and mulch between rows once seedlings are up.

When to plant

Rocket seed germinates in soil from about 10°C to 25°C, and plants crop longest in mild, cool weather. Sow salad rocket little and often, as in Three mistakes; wild rocket crops on from one sowing.

At the hot end of a window, sow where the row gets afternoon shade. At the cold end, cover autumn rows with frost cloth to keep them cropping, or sow in pots in a sheltered, sunny spot.

Site, soil and setup

Container growing

Salad rocket has shallow roots, so a wide, fairly shallow pot suits it. Use a pot at least 30 cm across, holding 10 to 15 L of premium potting mix, with good drainage holes. That fits about six plants. Good choices are 'Pronto' and Rocket (Organic), or the wild types 'Wild' and 'Olivetta', which stay compact at about 20 to 25 cm.

• Water: pots dry out fast, so check them daily and water daily in summer heat.
• Feed: fish and seaweed blend at 25 mL per 9 L, fortnightly, from the first true leaves.
• Position: as for beds, and move the pot out of the midday sun when the weather turns hot.

Sowing Seeds

Sow rocket straight where it is to grow, or raise it in punnets and transplant it.

Choosing a type

Due to quarantine restrictions and our shipping policy, we cannot send the wild rocket lines or the Heirloom Mix to Tasmania. We also cannot send 'Olivetta' to Western Australia. Some seed, including 'Salad', is treated with a fungicide: wear gloves, wash your hands after sowing, and never eat or sprout treated seed.

Sowing direct

• Rake the bed to a fine, level surface and water it before sowing.
• Salad rocket: sow 3 to 5 mm deep, thinly along a shallow row or scattered over a patch.
• Wild rocket: sow on the surface and barely cover it, about 3 mm at most, since deeper seed often fails to emerge.
• Keep the surface damp; salad rocket emerges in 5 to 10 days, wild rocket in 1 to 3 weeks.

Starting in punnets

Sow a pinch of seed per cell in seed-raising mix, 3 mm deep. Plant out when seedlings are 5 to 8 cm tall, after hardening off (getting them used to sun and wind over about a week).

Care by growth stage

Steady water and cool weather decide how long rocket keeps cropping. Weeks count from sowing.

If growth stalls in poor soil, a light dose of all-purpose controlled release granular (NPK around 14-5-10) can help. Scratch it into the soil at label rate. Water the soil rather than the leaves, in the early morning or late afternoon.

Thinning

How far apart to thin depends on how you pick. Rows cut young as baby leaf need no thinning; plants picked leaf by leaf need room to grow broad.

• Snip unwanted seedlings at soil level so the roots you keep stay undisturbed.
• Eat the thinnings in salads.
• Pull salad rocket once it flowers, and have the next sowing ready to take over.
• Shear wild rocket back when it turns woody or flowers heavily; it regrows from its taproot.

Companion planting

Good neighbours share rocket's cool, moist bed or confuse the cabbage white butterfly.

Grows well with

• Lettuce, which suits the same cool, moist bed and the same sowing rhythm.
• Dill and coriander, whose strong scent helps confuse egg-laying cabbage white butterflies.

Keep apart

• Cabbage, broccoli and kale, which share cabbage white caterpillars, diamondback moth and aphids.
• Mustard and cress, cabbage-family salad crops with the same pests.

Harvesting Leaves

Start picking once plants have enough leaves to spare a few, usually 3 to 6 weeks after sowing.

• Snap or cut the outer leaves near the base, and leave at least six leaves so the plant keeps growing.
• For baby leaf, shear the whole row about 3 cm above the soil; it regrows for a second cut.
• Cut wild rocket the same way.
• Pick in the cool of the morning, when leaves are crisp.
• Eat the flowers of both types in salads once plants bolt.

Rocket leaves are highly perishable. Store them in a perforated plastic bag in the fridge and eat them as soon as you can. Use rocket raw in salads, blend it into pesto, or wilt it through pasta, risotto and stir-fries.

Common problems

Plants flowering within weeks. Heat and dry soil push rocket to bolt; see Three mistakes, then resow in a cooler, shadier spot.

Leaves too hot or bitter. The bite strengthens as leaves age and as temperatures rise. Pick smaller leaves more often, keep the soil moist, or grow the milder 'Bulwinkle'.

Patchy or no seedlings. Seed sown too deep or a surface left to dry often fails, and wild rocket emerges best from seed at or near the surface. Read more

Wild rocket seedlings everywhere. Wild rocket spreads by seed, and each pod holds dozens, so cut flower stems before the pods ripen. On roadsides it grows wild as Lincoln weed, a declared weed in South Australia and Victoria. Gardeners there should check with their state authority before sowing it.

Pests and diseases

Use only sprays labelled for the pest on leafy vegetables, and keep to any withholding period before picking.

Cabbage white butterfly (Pieris rapae). Its caterpillars chew large holes in the leaves and leave green droppings behind. Pick the caterpillars off by hand. Read more

Diamondback moth (Plutella xylostella). Small yellow-green caterpillars feed under the leaves, leaving windows and small holes. The mesh in Prevention first keeps the moths off, and parasitic wasps help control them. Read more

Cabbage aphid (Brevicoryne brassicae) and other aphids. Grey-green colonies cluster under leaves and on young growth, sucking sap. Knock them off with a strong jet of water, or spray insecticidal soap under the leaves. Read more

Common garden snail (Cornu aspersum) and slugs. They hide by day in damp shelter and can chew young seedlings to stumps. Pick them off in the evening and remove their hiding places. Read more

Damping off (Pythium species and Rhizoctonia solani). Seed rots before it emerges, or seedlings collapse at soil level, most often in wet, crowded rows and punnets. Thin crowded seedlings and water only enough to keep the surface damp. Read more

Downy mildew (Hyaloperonospora parasitica). In cool, damp weather, yellow patches spread on the upper leaf with a greyish white growth beneath, worst in crowded seedlings. Water early in the day, thin for airflow and pull badly affected plants. Read more

Prevention first

• Cover rows with fine insect mesh from sowing, so butterflies and moths cannot lay eggs.
• Check leaf undersides weekly for eggs, caterpillars and aphids.
• Clear boards, rocks and leaf litter from bed edges, where snails shelter by day.
• Use fresh seed-raising mix and clean punnets, since damping off spreads in old mix and on dirty tools.

Tips

1. Grow rocket as microgreens in a tray of seed-raising mix at least 2 cm deep. Sow thickly with untreated seed, keep the tray somewhere bright, and cut the shoots above the mix at 2 to 3 weeks. People with weak immunity should avoid eating microgreens raw.
2. Leave one or two salad rocket plants to flower at the end of a row. The seed they drop often comes up as a free crop the next cool season.
3. In cold winters, sow 'Pronto' every couple of weeks in a large pot indoors, in a bright spot.