How to Grow Agrimony in Australia

Agrimony (Agrimonia eupatoria), of the rose family Rosaceae, is a hardy perennial grown for its tall spikes of small yellow flowers. It has a long place in the herb garden, copes with dry, lean ground and has gone wild in northern New South Wales and Queensland. The seed is where most gardeners come unstuck: sown warm and unchilled, it often sits in the tray for weeks and is thrown out.

Three mistakes that matter

1. Sowing the seed straight from the packet into a warm tray. The seed is dormant, and in one laboratory trial only about one seed in ten germinated without a cold spell. Chill it first, as Germinating the seed explains.
2. Planting in wet or shaded ground. Agrimony is a plant of dry, sunny banks and field edges. In deep shade or wet, acid soil it struggles, and roots left standing in water rot. Give it the sunniest, best-drained spot you have.
3. Letting every flower spike ripen. Each flower becomes a hooked burr that clings to socks and pet coats, and plants self-sow freely. Cut spent spikes before the burrs turn brown, keeping only the few you want for seed.

When to plant

Agrimony germinates in mild conditions, around 13 to 18°C, and far better once the seed has had a spell of cold. Sow in autumn and let winter do the chilling outdoors, or chill the seed in the fridge and sow in early spring. One planting lives for years, so a single sowing is usually enough.

A late autumn sowing in a frosty district may sit through winter before anything shows. Leave the pot outside, keep it just moist, and expect seedlings as the soil warms.

Site, soil and setup

In Europe agrimony grows wild on hedge banks, roadsides and the edges of fields, usually on alkaline, chalky soils.

Agrimony is a perennial that stays in one spot for years, so it sits outside the vegie patch rotation.

Container growing

A pot suits agrimony where garden soil is heavy or stays wet, and it keeps the burrs where you can see them. Use one plant to a pot at least 30 cm wide, about 13.5 L. Fill it with a free-draining potting mix that still holds some moisture. Common agrimony is sold as the plain species, so there are no compact varieties to choose between.

• Water: only once the top few centimetres of mix are dry, then until water runs from the drainage holes.
• Feed: worm casting liquid diluted to weak tea colour, fortnightly in spring only.
• Position: full sun, on pot feet so the base never sits in water.
• Dividing: when the clump fills the pot, split it in autumn and repot the pieces.

Germinating the seed

Each agrimony seed in the packet is a small, woody burr about 7 to 10 mm long. It is the hardened base of the old flower, holding one or two true seeds. That seed has physiological dormancy: most embryos rest until they have had a spell of cold. Chilling breaks it quickly, and trials found 10 days to a month of cold enough.

Agrimony is slow and uneven rather than truly hard. In a laboratory trial at 18°C, unchilled seed gave about 10 per cent germination in three weeks. Chilled seed gave about 45 to 57 per cent. In the garden, seedlings usually appear 2 to 6 weeks after sowing, and stored seed comes up less well. Sow two or three burrs for every plant you want, so a packet of 10 gives about three to five plants.

Laboratories use gibberellic acid, a plant growth hormone, on this seed. In one trial it did less than chilling, so chilling is the method to use at home.

When nothing comes up

• No cold spell. Unchilled seed often stays dormant. Bag the whole pot and chill it in the fridge for 2 to 4 weeks, then bring it out again.
• The bag dried out or went mouldy. A moist chill needs the mix kept just damp. Bin soft or mouldy burrs, rinse the rest and re-dampen the vermiculite.
• Sown too deep. A burr needs only about 5 mm of cover. Resow at that depth rather than burying it.
• Old or warm-stored seed. Stored seed loses vigour. Keep burrs cool and dry, and sow saved seed the following autumn.
• Given up too soon. Seedlings come up in dribs and drabs over weeks. Keep the pot moist for at least 8 weeks, past the usual 6, before sowing again.

Sowing Seeds

Start agrimony from seed chilled as Germinating the seed describes, in pots or direct in autumn; the guide to seed treatments covers the fridge.

Starting under cover

• Sow chilled burrs 5 mm deep in pots or a tray of seed raising mix, two or three per pot.
• Keep the mix just moist, at the temperature When to plant gives.
• Expect seedlings in 2 to 6 weeks, sometimes longer.
• Prick out the seedlings when they are large enough to handle, one to a pot.

Sowing direct

In autumn, sow three burrs 5 mm deep at each spot where a plant is wanted, 30 cm apart, and mark each one. Winter chills the seed in the soil, and seedlings appear as it warms. Thin each spot to the strongest seedling.

Transplanting

• Harden off seedlings first (move them outside for a little longer each day for a week or two), as the hardening off guide describes.
• Plant out in late spring in frosty districts, and in autumn or spring elsewhere.
• Space plants 30 cm apart, at the depth they sat in the pot.
• Water well for the first few weeks, until new growth shows the roots have taken.

Care by growth stage

Once its roots are down, agrimony needs very little: sun, drainage and a light hand with water and feed. Rich feeding is unnecessary for this herb.

If growth stalls in very poor soil, a light application of all-purpose controlled release granular (NPK around 14-5-10), scratched in once in spring, can help. In frosty districts the leaves die back over winter and regrow from the root in spring.

Cutting Back

Cut agrimony back for two reasons: to stop the burrs spreading, and to tidy the clump when it dies down.

• Cut spent flower spikes off at the base, as Three mistakes that matter describes.
• Leave a few spikes to ripen only if you want seed; Harvesting Stems covers collecting it.
• Cut the old stems to the ground once they die back in late autumn.
• Divide crowded clumps in autumn and plant the pieces straight into their new spots, as dividing perennials explains.
• Pull unwanted self-sown seedlings while they are small.

Companion planting

Agrimony sits best among herbs that also want sun, lean soil and little water.

Grows well with

• Thyme, which wants the same full sun and sharply drained, lean soil.
• Oregano, another lean-soil herb happy to dry out between waterings.
• Lavender, which likes full sun and does well in alkaline soil.

Keep apart

• Mint, whose runners take over a bed and which wants richer, moister soil.
• Comfrey, a large clump that regrows from any root piece and crowds smaller plants.

Harvesting Stems

Cut stems when the spikes flower in summer, 12 to 18 weeks after a spring sowing or the summer after an autumn one. Pick on a dry morning once the dew has gone.

• Wear gloves and long sleeves (see Safety), and cut each stem 2.5 to 5 cm above the ground with clean secateurs.
• Tie the stems into small, loose bunches so air reaches every one.
• Hang the bunches out of direct sun, somewhere warm with good air movement.
• Once leaves and flowers are crisp, strip them from the stems without crushing them.
• For seed, let a few spikes turn brown on the plant, then cut them and dry the burrs on paper for 3 to 6 weeks.

Store the dried material in airtight jars in a dark cupboard, labelled with the name and the date. Home-dried herbs generally keep about 12 months, and light fades them faster. Keep spare burrs in a paper envelope somewhere cool and dry, and sow them the next autumn.

Traditional use and history

Agrimony is native to Europe, North Africa and western Asia, reaching east to Afghanistan and Xinjiang in western China. In England it was a common plant of hedge banks and field sides.

Maud Grieve's A Modern Herbal records church steeples, for the tall flower spikes. Cockeburr, sticklewort and stickwort refer to the burrs that cling to passers-by. The Anglo-Saxons called it garclive, and in Chaucer's time it was written egrimoyne. The genus name is traced to argemone, a Greek name for plants used on the eyes. The species name honours Mithridates Eupator, who ruled Pontus and was credited in old accounts with bringing in many herbal mixtures.

In China and some other countries, the herb known as agrimony comes from a different species, Agrimonia pilosa. It is not the common agrimony sold as seed here.

Safety

Agrimony is sold as seed for growing, and nothing here is advice to eat or take any part of the plant. Anyone thinking of using a plant should first seek advice from a qualified health practitioner.

Common problems

Seedlings collapse at soil level. Damping off, a rot of young stems caused by soil fungi and water moulds, thrives in wet, crowded, airless trays. Water from below and sow thinly. Read more

Fewer flowers from an old clump. Perennials that have sat for three to five years often flower less as the clump crowds itself. Divide it in autumn, as Cutting Back describes.

Young plants wilting in their first summer. Roots have not reached down yet, so water every few days until new growth shows. Sparse growth in shade or wet soil is a site problem; see Three mistakes that matter.

Pests and diseases

Agrimony is rarely troubled, and most problems come from wet soil or humid, crowded planting.

Aphids (family Aphididae). Colonies on shoot tips and flower spikes suck sap and leave sticky honeydew, on which black sooty mould grows. Knock them off with a firm jet of water, or spray insecticidal soap. Read more

Powdery mildew (Erysiphales fungi). A white, powdery coating spreads over the leaves, worst in humid, still air around crowded plants. Water at the base and spray 1 part full-cream milk to 10 parts water at the first sign. Read more

Root rot (soil fungi and water moulds). Plants yellow, wilt and die in soggy, poorly drained soil, and affected plants seldom recover. Lift and bin them, then replant in a raised bed or pot.

Prevention first

• Remove the worst mildewed leaves as they appear, and clear badly affected stems when the clump dies back.
• Water at the base, and let the surface dry between waterings.
• Space plants 30 cm apart so air moves through the leaves.
• Check shoot tips and flower spikes weekly in spring for aphids.

Tips

1. Write the date in and the date due out on every stratification bag, so seed is not forgotten in the fridge.
2. Plant agrimony beside a path, where the faint apricot scent of the flower spikes can be enjoyed.
3. Let a clump flower near the vegie patch, because bees and flies visit the flowers.