How to Grow Lamb's Ears in Australia

Lamb's ear (Stachys byzantina) is a low, mat-forming perennial in the mint family (Lamiaceae). It is grown for its thick, silver, felted leaves and woolly spikes of small rose purple flowers. It comes from rocky hills between Turkey and Iran, so it suits Australia's dry summers and sulks wherever humidity lingers. Most failures come from kindness: wet soil, damp leaves and rich feeding harm it far more than a dry spell.

Three mistakes that matter

1. Burying the seed. Lamb's ear seed needs light to germinate, so seed pushed under the mix often never appears. Press it onto moist seed raising mix and cover it with no more than a dusting of vermiculite.
2. Planting in soil that stays wet. Roots and crowns rot in wet soil, and leaves that stay damp invite disease. Plant in free-draining soil or a raised bed, and let the soil dry out between waterings.
3. Treating it like a hungry bedding plant. Plants look best in lean soil, and in rich soil the clump spreads hard. Skip the manure and feed only as set out under Care by growth stage.

When to plant

Seed germinates at 18 to 22°C, so the warmth of the seed tray decides when to start. Sow in autumn while days stay warm, or in spring once a tray on a bright sill or a seedling heat mat holds 18°C. One sowing is enough, because each plant becomes a spreading clump that lasts for years.

Flowering needs vernalisation (a spell of winter cold that switches a plant over to flowering), so most plants flower after their first winter. At the cold edge of a window, raise trays indoors; at the humid edge, sow early so plants establish before the muggy months.

Site, soil and setup

A clump stays put for years, so there is no yearly rotation; set divisions into a fresh, well-drained spot. For ground that stays soggy after rain, read about waterlogged garden soil.

Container growing

Lamb's ear spreads sideways, so give it a pot or trough of about 50 to 70 L, at least 60 cm across, with drainage holes. Fill it with premium potting mix and stand the pot on feet so water drains away. The one variety in the range is 'Deep Rose', and its silver leaves set off brighter flowers planted in the same pot.

• Watering. Water when the top few centimetres of mix are dry, at the base of the plant, and empty any saucer. See watering pots through summer.
• Feeding. Give seaweed solution at 30 mL per 9 L every fortnight through spring, and nothing more.
• Position. Full sun. In heavy rain, move the pot under the eaves or onto a covered verandah.
• Dividing. Once the clump fills the pot, divide it in spring and repot the healthiest outer piece.

Sowing Seeds

Start lamb's ear in trays, where the light-hungry seed stays moist, lit and out of reach of snails.

Starting under cover

• Fill a clean tray with fresh seed raising mix, firm it and water it before sowing.
• Scatter the seed thinly and press it onto the surface without burying it (see Three mistakes that matter).
• Keep the tray at the temperature under When to plant, in bright light out of direct sun, under a clear cover. Water from below.
• Seedlings appear in 14 to 35 days. Lift the cover once they do, so air can move.
• Prick out each seedling into an 8 cm pot once it can be handled by a leaf, and grow it on somewhere cooler and bright.

Sowing direct

Seed can go straight onto raked, weed-free soil in mild autumn or spring weather. The seedlings are slow and easily lost to weeds and snails, so trays are the surer start. Press the seed onto the surface, keep it moist with a fine spray and thin seedlings to 30 to 45 cm apart.

Transplanting

Plant out once roots fill the 8 cm pot, usually 10 to 12 weeks after sowing and after the last frost. Harden seedlings off first (10 to 15 days of gradually longer spells outdoors that toughen soft growth), as in hardening off seedlings.

Set each plant at the depth it grew in the pot, 30 to 45 cm apart. Water it in with seaweed solution at 30 mL per 9 L. The wider spacing gives single plants room; the closer one knits into a carpet sooner.

Care by growth stage

Dry leaves, dry crowns and a light hand with feed decide how long a clump lives. Water deeply but rarely once plants settle, always at soil level.

If growth stalls in very poor soil, scratch a light dose of all-purpose controlled release granular (NPK around 14-5-10) around the clump in spring.

Trimming and Shaping

A little regular tidying keeps the mat silver and stops rot spreading. Nothing needs hard pruning.

• For a neat silver carpet, cut flower spikes off at their base as they appear. Leave them if you want flowers for bees and for cutting.
• Once flowering ends, cut the spent spikes back to the leaves.
• Pick off yellow, damaged or rotting leaves as soon as you see them, so rot cannot spread through the clump.
• At the end of winter, clear away dead leaves before new growth starts.
• Pull out or dig up rooted stems that creep beyond their space.
• Divide clumps every 2 to 4 years in spring, keeping the young outer pieces, as in dividing perennials.

Companion planting

Lamb's ear belongs at the sunny front of a dry border, beside plants that want the same lean, free-draining soil and sparse water.

Grows well with

• Lavender, a low-water herb that shares its sun and sharp drainage.
• Thyme and sage, dry-soil herbs that suit the same watering.
• Roses, which it underplants well, as long as the rose bed is not kept wet.
• Catmint and sedums, whose flowers and fleshy leaves contrast with the silver felt.

Keep apart

• Lettuce and other thirsty crops, whose frequent watering keeps lamb's ear too wet.
• Impatiens and other shade lovers, which need moist soil and shelter it does not want.
• Mint, a fast spreader of damp soil that competes for the same ground.
• Sunflowers and other tall, dense plants, whose shade keeps the woolly leaves damp.

Harvesting Stems

Cut flower stems as the lowest flowers on a spike begin to open. Pick leaves whenever the clump is growing strongly, from about 23 weeks after sowing.

• Cut in the late morning, once dew has dried, and never when the plant is wet from rain.
• Cut each stem close to the base of the plant, so picking doubles as tidying.
• Stand stems in a shallow container of water as you pick, so they do not wilt and set crooked.
• Take leaves from near the base, and no more than a third of the clump at once.
• Leave a few spikes to ripen if you want seed; the small brown nutlets form in the old flowers.

To dry stems, strip the larger lower leaves and band the stems into bundles 2.5 to 4 cm across. Bigger bundles dry slowly and can go mouldy. Hang them upside down in a dark, airy room at room temperature. They are ready in two to four weeks, once stiff and papery.

Damp air can make dried heads droop, so keep them somewhere dry and lay them flat or angled in arrangements. Use the leaves in fresh posies and the dried stems in wreaths and dried arrangements.

Common problems

Seeds did not come up. Buried seed (see Three mistakes that matter), a tray that dried out or one kept below 18°C are the usual causes. Slow seed can take five weeks. Read more

Brown, mushy leaves in summer. The woolly leaves hold water, so rain and humidity rot them, worst in crowded clumps; pick them off and thin or divide the clump.

Whole clump collapses. Root and crown rots take hold when soil stays wet; lift any healthy pieces into better drainage. Read more

No flower spikes. Young plants flower only after a winter's chill, so warm-zone plants may flower little; spikes cut off early also mean no flowers.

Bare, dead centre. An old clump has worn out in the middle; divide it as under Trimming and Shaping.

Plants creep into paths. Stems root where they touch soil and spikes can self-sow; trim runners and cut spent spikes before they drop seed.

Pests and diseases

Few pests bother the felted leaves; snails at the seedling stage and mildew in muggy weather are the main ones to watch.

Common garden snail (Cornu aspersum). This introduced snail lives in every state and territory, away from the tropics and desert. It chews seedlings and soft young leaves, as do slugs. Hunt them under leaves and rocks, sink shallow beer traps or ring pots with copper tape. If you bait, scatter an iron-based bait thinly, because a dog that eats a large amount of any snail bait can be poisoned. Read more

Powdery mildew (order Erysiphales). White to greyish patches spread over leaves and stems; plants do not usually die, but they look shabby. Remove badly affected leaves and, on a sunny morning, spray 1 part full-cream milk to 10 parts water. Read more

Damping off (Pythium species and Rhizoctonia solani). These soil-borne pathogens rot seedlings at soil level, so they topple over in the tray. Read more

Prevention first

• Sow in fresh seed raising mix in clean trays, and lift the cover once seedlings appear.
• Give plants room and divide crowded clumps so air moves through them.
• Water at soil level in the morning, never over the leaves.
• After rain, check under leaves and around rocks where snails shelter by day.

Tips

1. Plant it beside a path or between stepping stones, where people brush past and stroke the leaves. It is a favourite in children's gardens.
2. Use the silver leaves as a foil for bold flower colours, or in a moon garden of white flowers and silver leaves.
3. Pot up spare divisions for friends, and water each one well for its first couple of weeks.