How to Grow Sage in Australia

Sage (Salvia officinalis) is a woody, evergreen perennial of the mint family, Lamiaceae, grown for its soft grey-green leaves, used fresh or dried. It comes from the dry hills of the northern Mediterranean. Perth sand or a pot on a hot balcony suits it better than a rich, well-watered vegie bed. One healthy bush is usually enough for a household.

Three mistakes that matter

1. Planting into wet or rich soil. Sage roots rot in soggy ground, and compost, manure and frequent watering give soft growth with weaker flavour. Plant into lean, free-draining soil, a raised bed or a pot, and water only once the top has dried.
2. Cutting back into bare wood. Old, leafless sage stems may not reshoot, so a hard cut can leave a bare frame that never recovers. Trim into leafy growth instead, and renew tired bushes as Trimming and Shaping describes.
3. Stripping a young plant. Seed-raised sage grows slowly and can take about a year to reach full picking size. Take only a few leaves from about 12 weeks, so the young bush fills out before the heavier picking begins.

When to plant

Sage seed germinates best with the mix at 18 to 21°C. Sow when trays can be held at that warmth: winter to early summer outside the tropics, and the dry season within them.

Seedlings raised late can wait in their pots in a bright, sheltered spot until spring, or in the tropics until the dry season returns.

Site, soil and setup

Give sage the sunniest, driest and best-drained spot you have. Sun all day brings out its aromatic flavour.

When a worn-out bush is replaced, plant the new one in a fresh spot, away from any soil where roots have rotted.

Container growing

A pot suits sage well, because drainage and wet weather are easier to control. Give one plant a pot at least 30 cm wide and 30 cm deep. A standard 40 cm pot is 32 cm deep and holds about 28 L. Fill it with premium potting mix, with coarse grit added up to a quarter of the volume. Both packets, the 20-seed and the 30-seed, grow common sage, a bush that can spread 40 to 80 cm, so allow for its full size. Potting and seed-raising mixes can carry Legionella bacteria, so wet them down, wear gloves and a P2 mask, and wash your hands afterwards.

• Water: once the top 2 cm of mix is dry, until water runs from the holes. Keep it slightly moist, never saturated, and check often in summer.
• Feed: fish and seaweed blend at half strength, about 12.5 mL per 9 L, fortnightly from spring to late summer.
• Position: full sun, sheltered from strong wind, and moved under the eaves through long wet spells.

Sowing Seeds

Start sage in small pots or punnets and plant it out. Direct sowing also works into a fine, weed-free bed once the soil is warm.

Starting under cover

• Sow 2 to 3 seeds per 10 cm pot or cell, 5 mm deep, in moist seed-raising mix.
• Cover with a clear lid or bag, keep the mix at the temperature When to plant gives, and lift the cover once seedlings appear.
• Expect seedlings in 10 to 21 days.
• Thin each pot to its strongest seedling.
• Keep the seedlings warm and bright, and pot them on into larger pots as they grow.

A seedling heat mat holds that temperature in a cool spring.

Planting out

• Harden off the young plants (move them outdoors a little longer each day so they adjust to sun and wind), starting at four true leaves.
• Give them 2 to 3 hours in light shade on day one, then 1 to 2 hours more each day for about a week.
• Plant out once they are about 10 cm tall, with the top of the root ball only lightly covered.
• Space plants 45 to 60 cm apart, since a mature bush spreads wide.
• Water them in with seaweed solution at half strength, 15 mL per 9 L.

Care by growth stage

Dry roots and full sun decide how well sage grows. Over-feeding reduces the essential oils that give sage its flavour and aroma, so feed at half strength at most.

Ease off watering through the cool months, when wet soil rots the roots. If growth stalls in very poor sand, a light scatter of all-purpose controlled release granular (NPK around 14-5-10) in spring can help.

Trimming and Shaping

A light trim each spring and after flowering keeps sage compact and leafy, and slows its slide into a woody, open bush.

• Trim lightly in spring as new growth starts, cutting each stem back to just above fresh leaves.
• Cut off the faded flower stems once flowering ends.
• Remove dead, woody stems, but leave the new growth.
• In Perth's long, hot summers, a firmer trim in late autumn brings fresh growth for winter and spring; still cut above leaves.
• Replace the bush every three to four years with a rooted cutting or layer, as Tips describes. In humid districts sage can be short-lived, so keep a rooted cutting ready.

Companion planting

Sage suits sunny, lean-soil neighbours that share its dislike of wet feet.

Grows well with

• Thyme and oregano, which want the same full sun and free-draining soil.
• Rosemary, another Mediterranean shrub that needs dry roots.
• Cabbage, broccoli and cauliflower, with sage along the bed edge, where its flowers draw bees and beneficial insects.

Keep apart

• Basil and parsley, which need the richer soil and steady water that rot sage roots.
• Mint, which spreads by underground runners and wants moist soil.

Harvesting Leaves

Because sage is evergreen, established plants can be picked all year, and fresh spring growth has the best flavour.

• Pick young leaves or whole shoot tips from around the bush, rather than stripping one side.
• Take no more than a third of the plant at a time.
• For drying, cut 15 to 20 cm stems just before flowering, when the flavour is strongest.
• Pick in the morning once the dew has dried.

Hang small bundles upside down in a dark, dry, airy place until the leaves are crisp, usually one to two weeks in dry air. Store them in an airtight container in the dark, where they keep their flavour for several months. Chopped fresh leaves also freeze well in ice cube trays.

Use sage with pork, chicken stuffing and sausages, or fry the leaves in brown butter for pumpkin and pasta.

Common problems

No seedlings. Seed kept too cold, sown too deep or allowed to dry out often fails, so check the mix temperature and sow again. Read more

Tall, pale seedlings. Seedlings kept in too little light stretch towards it, so move the pots to bright light at once. Read more

A bush that sprawls or snaps. Older plants sprawl, and strong wind can snap the main stem, so stake or shelter exposed plants and trim as Trimming and Shaping describes.

Tired leaves by late summer. Long, dry heat can leave sage looking worn, especially in Perth, so shade it in the hottest months as Site, soil and setup describes.

Pests and diseases

Sage has few pest problems, and most of what goes wrong follows wet roots or humid, still air.

Root and crown rot (Phytophthora species, a soil-borne water mould, and other soil fungi). Leaves yellow, the plant wilts and the whole bush can collapse, most often in wet, poorly drained soil. Lift and discard it, then replant in drier ground or a raised bed.

Powdery mildew (Golovinomyces species). White, powdery patches spread over the leaves and stems, worst in humid weather with poor air movement. Remove badly affected leaves and spray 1 part full-cream milk to 10 parts water. Read more

Downy mildew (Peronospora lamii). Light brown blotches bounded by the leaf veins darken, then the leaves drop, with grey-brown growth underneath. Pick up fallen leaves and bin them rather than composting. Read more

Slugs and snails, mainly the common garden snail (Cornu aspersum). They chew seedlings and new leaves at night, most after rain. Collect them by torchlight about two hours after sunset, or set shallow beer traps. Read more

Damping off (Pythium and Rhizoctonia species). Seedlings collapse at soil level, most often in wet mix sown thickly. Sow thinly into fresh mix, avoid overwatering and keep pots well drained. Read more

Prevention first

• Grow sage in a pot or raised bed wherever summers are humid.
• Keep the spacing Planting out gives, and trim so air moves through the bush.
• Water the soil in the morning, not the leaves.
• Keep mulch and fallen leaves clear of young plants, since snails hide in them by day.

Tips

1. Look for low stems that have rooted where they touch the soil, and pot them up as replacement plants.
2. Take softwood cuttings from new growth in late spring or early summer, well before the old bush wears out.
3. Grow a row of sage as a low hedge or border along a vegie bed, where it is close at hand for picking.