How to Grow Meadowsweet in Australia

Meadowsweet (Filipendula ulmaria) is a clump-forming perennial of the rose family, Rosaceae, grown for its frothy heads of scented cream flowers above elm-like leaves. It belongs at a pond edge, in a bog garden or in any bed that stays damp, and it is fully frost hardy. Many failures start at sowing: the seed needs light and does best after a cold spell, yet often goes in too deep and too warm.

Three mistakes that matter

1. Burying the seed or keeping it warm. Buried seed comes up poorly or not at all, and warm, unchilled seed can be slow and patchy, sometimes taking months. Chill it first, then press it onto the surface in cool conditions, as Germinating the seed explains.
2. Letting the soil dry out. Meadowsweet does not tolerate drought, and dry soil scorches its leaves. Plant it where the ground stays moist all year, mulch it, and water before the surface dries.
3. Leaving every flower head to set seed. It self-seeds freely and can spread out of control. Cut the heads for the house or remove them after flowering, as Cutting Back describes.

When to plant

Sow in autumn, through winter where winters are mild, or in late winter to spring, because a cold, moist spell gives fuller, more even germination. Once chilled, it comes up at about 10 to 20°C, best at the cool end of 10 to 13°C. Time spring sowings for mild days before the heat. In cool districts, a tray sown around Anzac Day and left outdoors lets winter do the chilling for you.

Where the calendar marks a zone as marginal or not recommended, the reason is heat and dry air rather than frost.

Site, soil and setup

In the wild, meadowsweet grows in wet meadows, marshes and along riverbanks.

Container growing

A large pot lets meadowsweet grow where the garden soil is too dry. Give one plant a pot at least 40 cm across, which holds about 28 L. Fill it with potting mix blended with about a third compost to hold water. A wicking box, which waters from a reservoir below, suits it well. Only the species is sold, so there is no compact form to choose.

• Water: daily in warm weather, until water runs from the base, and never let the mix dry out.
• Saucer: stand the pot in a deep saucer kept topped up through summer, and empty it in winter.
• Feed: worm casting liquid diluted to weak tea colour, fortnightly from spring to late summer.
• Position: morning sun and afternoon shade, out of hot wind.
• Repotting: divide the clump once roots fill the pot, usually every few years.

Germinating the seed

Meadowsweet seed needs light, so it germinates on the surface or under the thinnest dusting of mix. In the wild it lies through winter and comes up in spring. A spell of cold, moist conditions gives fuller, more even germination, although chilling is not essential.

It is slow rather than hard. After chilling, seedlings usually appear in 2 to 4 weeks, but unchilled or warm seed can take three months or more. In seed bank tests recorded in the Seed Information Database, 84 to 96 per cent of seed germinated in light, with no pre-treatment recorded. Those tests alternated day and night temperatures of about 25 and 10°C. A home tray is less controlled, so sow 2 or 3 seeds for each plant wanted.

When nothing comes up

• Sown too deep. Seed needs light, so resow on the surface and press it in.
• The mix dried out. Dry mix halts germination; cover the tray with glass or clear film and mist it.
• Too warm. Move the tray somewhere cooler and shaded, around 10 to 13°C.
• Mould in the bag. Bin mouldy seed, rinse the rest and use barely damp material next time.
• Not enough cold. Give the seed another 2 to 4 weeks in the fridge, then sow again.
• Given up too soon. Keep the tray moist for three months, or leave it outdoors through winter for a spring flush.

Sowing Seeds

Start with chilled seed, as described in Germinating the seed, or with an autumn tray left outdoors. Trays make seed this small and slow easier to watch and weed. Read more

Starting under cover

• Fill a tray or cell pots with moist seed raising mix and firm it gently.
• Sow 2 or 3 seeds per cell, or scatter thinly across a tray.
• Press the seed in, or cover it no more than 1 to 2 mm deep.
• Keep it in bright light at 10 to 20°C, and never let the surface dry.
• Expect seedlings in 2 to 4 weeks from chilled seed.

Sowing direct

Direct sowing only suits a bed that stays wet and weed free. Scatter the seed on the surface in autumn, mark the spot, and keep it moist so winter can chill it in place.

Transplanting

• Prick out seedlings into 8 cm pots once they can be handled. Hold each by a leaf, not the stem, and replant it at the same depth.
• Grow them on in a cool, lightly shaded place, kept moist.
• Harden them off (a week or two of gradually longer spells outdoors) before planting. Read more
• Plant out 40 to 60 cm apart in autumn or spring, and water in well.
• Keep late or small seedlings in pots over winter and plant them out the next spring.

Care by growth stage

Water decides this crop far more than feeding. Rich, moist soil carries it, so feed lightly and at half strength.

If growth stalls in poor soil, a light application of all-purpose controlled release granular (NPK around 14-5-10) scratched in each spring can help. Pull weeds by hand while plants are small.

Cutting Back

Cut back after flowering to stop self-seeding and to tidy the clump. A hard cut also renews foliage spoiled by heat, dryness or mildew.

• Cut spent flower stems to the base of the plant once flowering ends.
• Remove flower spikes as they appear if you grow it for foliage alone.
• Cut scorched or mildewed foliage hard to the ground, water well, and fresh leaves usually follow.
• Clear dead stems and leaves in late autumn or winter as the plant dies back.
• Divide crowded clumps in late winter or early spring, replanting the healthy outer pieces. Read more

Companion planting

Pair meadowsweet with plants that want the same wet ground, and keep it clear of spreaders and dry-soil herbs.

Grows well with

• Other moisture-loving perennials for a bog bed or pond margin, which share its constant watering.
• Deciduous trees or tall shrubs to the west, which give afternoon shade in summer.

Keep apart

• Mint, whose runners cross a bed and push into the meadowsweet clump.
• Lavender and thyme, which want lean, free-draining soil and suffer root rot in the wet ground meadowsweet needs.

Harvesting Blooms

Cut flower heads early in flowering, when only part of each head is open, because the scent is strongest then.

• Take the whole stem with sharp secateurs, just above a leaf.
• Stand stems for the vase in a bucket of water straight away.
• For drying, tie small bunches and hang them upside down in a dry, airy room out of the sun.
• Leave some heads on the plant if you want seed, then cut the rest before they ripen.

Once the heads are completely dry, store them in a sealed jar in a cool, dark cupboard, labelled with the plant's name.

Fresh stems make a scented filler for the vase.

Traditional use and history

Meadowsweet is native to Europe and western Asia, where it grows on wet ground by rivers, in marshes and in wet woods. It is not recorded as naturalised in Australia: the Australian Plant Census holds no entry for the genus.

Maud Grieve's A Modern Herbal records that in the fourteenth century it was called medwort or meadwort, the mead or honey-wine herb. The same book lists bridewort, lady of the meadow and dolloff among its names. The species name ulmaria refers to leaves likened to those of the elm, Ulmus, and Filipendula joins the Latin words for thread and hanging.

Outside its home range, it has escaped gardens and naturalised in parts of eastern North America. Some states of the American Midwest list it as a noxious weed. That is why Cutting Back asks for the heads to go before they seed.

Safety

Meadowsweet 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 caused by soil-borne water moulds (Pythium species) and fungi such as Rhizoctonia solani, thrives in wet, crowded trays. Sow thinly in fresh mix and avoid overwatering. Read more

Small plants and no flowers in the first year. Young plants build roots before they grow tall, so most flower from the second summer; keep them moist and be patient.

Plants decline through hot summers. In warm districts, full sun and hot wind stress the leaves even in moist soil. Move the plant to afternoon shade, or grow it in a pot that can follow the shade.

A bare, tired centre in an old clump. Crowded clumps lose vigour in the middle, so lift and divide them, replanting the young outer pieces into compost-enriched soil.

Pests and diseases

Meadowsweet has few serious pests, but its damp home suits snails, and its leaves can mildew in humid weather.

Common garden snail (Cornu aspersum) and grey field slug (Deroceras reticulatum). Both feed at night in damp weather and can strip seedlings and young shoots, especially in higher-rainfall southern Australia. Hand-pick them after dark or trap them under boards. Read more

Aphids (family Aphididae). Small soft-bodied insects cluster on new shoots and flower buds in spring, distorting growth. Hose them off, or spray insecticidal soap or horticultural oil as the label directs, never in hot weather. Read more

Powdery mildew (Podosphaera species). White powdery patches spread across the leaves, most often in warm, humid weather. Remove the worst leaves, water the soil rather than the foliage, and spray 1 part full-cream milk to 10 parts water. Read more

Prevention first

• Raise seedlings in fresh seed raising mix on a raised bench, away from garden soil.
• Space plants 40 to 60 cm apart so air moves through the clumps.
• Water in the morning at the base, so the leaves dry during the day.
• Check seedlings and young shoots after dark for snails and slugs.

Tips

1. Plant it where you pass on summer evenings but not under a bedroom window, because some people find the scent too strong.
2. Save seed from a head or two left on the plant. It ripens from late summer into early autumn, in time for a tray left outdoors. Keep any spare seed dry, in a sealed jar in the fridge.
3. Share a large clump when dividing: a well-rooted piece fills a wet corner faster than seed.