How to Grow Strawberries from Seed in Australia

Alpine strawberry (Fragaria vesca) is a small, clump-forming perennial in the rose family, Rosaceae, grown for tiny, intensely fragrant red or creamy white fruit. Unlike garden strawberries it comes true from seed, suits pots and edges, and in a mild garden can fruit from spring well into autumn. Most failures start at sowing, when the dust-fine seed is buried out of the light it needs.

Three mistakes that matter

1. Burying the seed. Seed kept in darkness fails to germinate, so a tray covered with mix often stays bare. Sow on the surface, as Sowing Seeds describes.
2. Giving up too early. Seedlings appear over two to eight weeks, and not all at once. Keep the tray warm and moist for the full eight weeks, and lift the first seedlings without disturbing the rest.
3. Baking the plants. Alpine strawberries have shallow roots, and hot afternoon sun or a dry spell slows their fruiting. Choose a spot as Site, soil and setup describes, mulch well and water evenly.

When to plant

Sow under cover, where the seed-raising mix stays at about 18 to 22°C. A winter sowing is then ready to plant out in spring. In cool months a seedling heat mat keeps the mix at that warmth. One sowing is enough, because the plants crop for several years.

A late sowing still works, since plants raised in spring often fruit in their first summer. Keep autumn sowings under cover until the frosts pass.

Site, soil and setup

See soil pH explained for testing. Rotate beds: do not plant where tomato, capsicum, chilli or eggplant grew in the past three years, as they can pass on disease.

Container growing

Alpine strawberries suit pots, troughs and hanging baskets, and pots help keep fruit clear of slugs. Give one plant a pot at least 20 cm across, about 4 L, or set three or four plants in a big hanging basket. Use premium potting mix. 'Ali-Baba', 'White Soul' and 'Baron Solemacher' are all compact enough for pots.

• Watering: shallow roots dry out fast, so check pots daily in warm weather. See watering pots in summer.
• Feeding: fish and seaweed blend at 25 mL per 9 L, fortnightly, switching to liquid potash at the label rate once flower buds show.
• Position: morning sun, moved into shade on hot afternoons and heatwaves.

Sowing Seeds

Raise alpine strawberries in trays under cover, then plant them out once they are well grown. Garden strawberries grown from bare-root runners have their own guide, growing strawberries from runners.

Preparing the seed

Many growers chill the seed first. Seal the dry seed in a closed jar or plastic box and keep it in the freezer for 2 to 4 weeks. Let the container warm to room temperature before opening it, so no moisture condenses on the seed. The chill is optional, and unchilled seed also comes up. It is a dry chill, not cold stratification (a moist cold spell in the fridge), which alpine seed does not need.

Sowing in trays

• Fill a tray with fine seed-raising mix and water it before sowing.
• Scatter the seed thinly on the surface and press it in; the sand trick helps spread it evenly.
• Leave it uncovered, or add only a dusting of fine sand, so light reaches the seed.
• Cover with clear plastic or glass, mist or water from below, and hold the mix at the warmth When to plant gives.
• Pot each seedling into its own small pot once it has three leaves.

Planting out

• Plant out when each plant has a good root system and after the last frost, since young seedlings are cold tender.
• Harden off (get seedlings used to sun and wind outdoors) over one to two weeks first.
• Set the crown, where leaves meet roots, level with the soil surface: buried too deep, it rots.
• Water in with seaweed solution at 30 mL per 9 L.
• Mulch with straw or pine needles, leaving a small gap around each crown.

Care by growth stage

Even moisture and a light hand with nitrogen decide the crop. Weeks count from sowing and shift with zone and weather.

Birds take ripe fruit. Plant closely, or cover the bed with white, wildlife-safe netting, pulled taut, with mesh too small for a finger to pass through.

Division and Maintenance

Plants crop best for two to four years, then turn woody and bear less. Divide them every three years, in spring or autumn, even if you need no extra plants.

• Dig up the clump and cut off young outer pieces, each with roots attached.
• Replant the pieces at the old depth and compost the woody centre; see dividing perennials.
• Replant in a fresh bed every three years, to stay ahead of diseases that build up in old beds.
• Most alpine forms make few or no runners; snip off any that crowd the clump.
• Remove old, spotted leaves and spent fruit stalks through the season.
• Top up the mulch every spring, keeping it clear of the crowns.

Companion planting

Alpine strawberries do best with room and air around them, and with bees close by.

Grows well with

• Borage, whose flowers bring the bees that set well-shaped fruit.
• Lettuce and spinach, low, quick crops that fill gaps between young plants.

Keep apart

• Potato, tomato, capsicum, chilli and eggplant, which can pass diseases to strawberries growing beside them.
• Cabbage family crops, which compete for nutrients.

Harvesting Fruit

Plants raised from seed often start fruiting 4 to 5 months after sowing, though some take up to a year. Pick when the fruit is fully coloured, soft and so fragrant it scents the air: before that it tastes bland.

• Check plants every 2 to 3 days while they fruit.
• Snip the stalk or pinch it through, rather than pulling the soft fruit.
• Pick into a shallow container, one layer deep, since ripe fruit crushes easily.
• Remove damaged or mouldy fruit as you pick, so rot does not spread.

Alpine fruit keeps only two or three days once picked. Store it unwashed in the fridge and wash it just before eating. For longer keeping, freeze it: it softens on thawing but suits smoothies, sauces and desserts.

Eat alpine strawberries fresh, scatter them over desserts and fruit salads, or use them to garnish drinks.

Common problems

Nothing comes up. Seed buried out of the light, a tray that dried out or ran cold, or a tray abandoned too early; see Three mistakes. Read more

Small, misshapen fruit. Poor pollination from wet weather or frost at flowering or few bees, or Rutherglen bugs (Nysius vinitor) feeding in flowers in warm, dry spells.

Bronzed, seedy fruit. Western flower thrips (Frankliniella occidentalis) feed in flowers and fruit in warm, dry weather, leaving fruit bronzed and rough around the seeds, or misshapen. Hang a sticky trap nearby to spot them early, and keep down flowering weeds such as clover. Read more

Firm, dark, sunken spots on fruit. Black spot (Colletotrichum acutatum), a fungus of warm, humid, wet weather, spreads by rain splash and on pickers' hands. Bin spotted fruit and old leaves, and water the soil rather than the plants.

Pale fruit with poor flavour. This follows overcast weather and too much nitrogen, so go easy on nitrogen feeds.

Fruit eaten before you pick it. Birds, slugs, snails, rats and possums all take ripe fruit. Net the bed as Care by growth stage describes, and mulch under the fruit. Read more

Pests and diseases

Mites, thrips and Rutherglen bugs build up in warm, dry weather, while grey mould, leaf spot and black spot follow wet, humid weather.

Two-spotted mite (Tetranychus urticae). Leaves speckle and mottle, then purple, with fine webbing between them in heavy attacks. Outbreaks build in warm, dry weather from spring. Control weeds nearby, which shelter mites, and encourage predatory mites. Read more

Green peach aphid (Myzus persicae). Aphids cluster under leaves and around flower buds, and their honeydew grows sooty mould on fruit. Squash small colonies or spray insecticidal soap. Read more

Queensland fruit fly (Bactrocera tryoni). A minor pest of strawberries across eastern Australia, most active from October to April. Maggots develop inside ripe fruit, so pick promptly and collect fallen fruit at once. Seal it in a bag and freeze it for two days, or boil it, before binning it. Read more

Grey mould (Botrytis cinerea). Fruit browns at the stalk end and grows a grey, cottony fuzz. It spreads in mild, humid, rainy weather, so remove affected fruit and keep fruit off wet soil.

Powdery mildew (Podosphaera aphanis). White, web-like patches form on leaves, whose edges curl up, and young fruit can harden. At the first spots, spray 1 part full-cream milk to 10 parts water. Read more

Strawberry leaf spot (Mycosphaerella fragariae). Small purple spots on the leaves turn pale in the centre. Rain splash spreads it in wet, cooler weather, so pick off spotted leaves.

Prevention first

• Water the soil in the morning, keeping leaves and fruit dry.
• Space plants for airflow, keep beds weeded and mulch under the fruit.
• Check leaf undersides and flower buds every week.
• Spare the bees that shape every fruit: if you must use pyrethrum, spray late in the day, away from open flowers. With any spray, follow the label and pick only after its withholding period.

Tips

1. Alpine strawberries come true from seed, so seed from your ripest fruit can raise the next bed.
2. A potted plant on a sunny windowsill can fruit early in spring; dab its flowers with a soft brush to pollinate them indoors.
3. Alpine strawberries are at home in a cool climate and are grown for market on the NSW southern tablelands, so frost need not deter you.