Lewisia: Jewel Flowers for Walls and Troughs

Lewisia gives you some of the brightest flowers you can fit in a wall: pink, salmon, apricot and magenta stars, often striped, above a neat evergreen rosette. Plenty are bought in flower each spring and lost by the next one.

They rarely die of cold. They die because water sat in the rosette and rotted the neck. Keep the neck dry and lewisia is one of the easiest alpines going. This guide shows you where to plant it, the tilted-planting trick, how to water it, and how to get it through winter.

What is lewisia?

Lewisia is a small group of alpines from the mountains of western North America, named after the explorer Meriwether Lewis. Nearly every plant sold in the UK is Lewisia cotyledon or one of its hybrids. In the wild it grows wedged into cliffs and rocky slopes, where rain runs straight off the leaves.

That explains how to grow it. It makes a flat rosette of fleshy, spoon-shaped leaves on a thick root. The leaves store water, so it shrugs off dry summers. Flowers come on short branched stems in hot colours that are unusual for an alpine.

Lewisias come in a run of hot shades from salmon to magenta, many of them striped.

Which lewisia should you grow?

All the common lewisias want the same care, so choose by colour, size and how long you’d like flowers.

Sunset Group is the classic garden-centre lewisia. It’s a seed strain in mixed pink, orange, salmon and yellow, often striped. It flowers well in May and June, with smaller repeat flushes if you deadhead.

Elise series was bred to flower in its first year from seed and to keep flowering from spring into autumn. It comes in mixed and single colours. Choose it if you want the longest season.

‘Little Plum’ is a compact hybrid with rose-purple flowers. Its smaller rosette suits a shallow pan or a tight trough.

Lewisia tweedyi has large peach-pink flowers but is fussier about wet. It’s best kept in an unheated alpine house.

Why do lewisias rot at the neck?

The rosette works like a cup. On a cliff, rain runs straight off. On a flat border in a mild, damp winter, water pools in the centre and the fleshy neck softens. By spring the whole top can lift off the root.

Rot is worst from November to March, when the plant barely grows and nothing dries out. A careless splash from a watering can in autumn can start it too. Four habits keep lewisia alive:

• Plant it tilted so the rosette sheds water.
• Keep the neck out of wet soil with a deep collar of grit.
• Water the compost, never the plant.
• Keep rain off the crown in winter, while letting air move around it.

Where to plant lewisia

A wall crevice or steep slope is the perfect home. Give it good light but shelter from the fiercest afternoon sun. An east or west-facing wall works well. In a hot, south-facing pot the rosettes can scorch in July. In deep shade it hardly flowers.

Lewisia likes lime-free, sharply drained soil. Avoid chalky pockets and old mortar rubble. If you’re planting into an old wall, pack the joint with a mix of ericaceous compost and grit. On ordinary soil, dig in plenty of grit and plant on a mound or slope. A crevice garden or a well-built rockery gives it exactly the conditions it likes.

Gardener’s tip: Garden centres sell lewisias flat on wet benches because they only need to look good for a few weeks. Tilt the rootball on its side when you plant it and it won’t sit in water again.

How to plant lewisia in a wall or crevice

Plant lewisia tilted, with the rosette facing outwards, so rain runs off the leaves. It takes a couple of minutes and makes the biggest difference of anything you do.

1. Pick a joint or crack at least 5cm deep, ideally with a stone above it like a little roof. A few courses up a wall is better than ground level, where splashing keeps the leaves wet.
2. Soak the plant, then knock it out of its pot and tease away loose compost so the rootball slims down.
3. Pack the back of the crevice with half ericaceous or John Innes compost and half grit.
4. Slide the root in sideways or at an angle, with the rosette sitting proud of the wall face.
5. Wedge small stone chips under and around the neck to hold it firm and keep it dry.
6. Water the joint above the plant for the first few weeks while it roots. After that, rain usually does the job.

Planted sideways in a wall joint, the rosette sheds rain just as it would on a cliff face.

In open ground or a raised bed, plant on a mound and tilt the rootball a little. Then add a grit collar: a 2-3cm layer of coarse chippings tucked right under the leaves, so the neck touches stone rather than soil. The grit dries off fast after every shower.

A collar of grit under the leaves keeps the neck off wet compost.

Growing lewisia in troughs and pots

A trough or clay pan lets you control drainage, angle and winter cover. Use a container at least 15cm deep with big drainage holes. Fill with half John Innes No. 2 and half horticultural grit. Plant on a slight mound or against a piece of stone set on edge, tilted as before. Finish with a layer of grit or slate chippings, and stand the container on feet.

A trough under the eaves stays dry in winter, which lewisia loves. It also misses summer showers, so check it weekly from May to September. Sempervivums, saxifrages and aubretia like similar gritty conditions and make good companions. Our guide to alpine troughs has planting ideas.

In pots, watch for vine weevil. The grubs eat the roots and the plant collapses suddenly. See our guide to vine weevil treatment for nematodes and other controls.

A raised stone trough gives lewisia perfect drainage. Sempervivums and saxifrages enjoy the same gritty mix.

Watering and feeding lewisia

Water the compost beside the plant, never the rosette, and let it dry out between drinks. Established plants in the ground rarely need more than rain. Pots and troughs dry faster, so give them a good soak in hot spells once the top few centimetres have dried. From autumn to spring, hardly water at all.

Feed lightly. A half-strength tomato feed once or twice in spring is plenty. Rich compost and heavy feeding make soft, floppy growth that rots easily.

How to keep lewisia flowering

Lewisia flowers from May to June, and Elise keeps going into autumn. To stretch the season, cut each spent flower stem off at its base. The plant then puts its energy into more flowers instead of seed, and often sends up a second flush in midsummer.

If a healthy plant won’t flower, the usual causes are too much shade, compost that’s too rich, or a young rosette that is still building up. More light and leaner compost usually fixes it by the next year.

How to propagate lewisia

Offsets are the small side rosettes that grow around the base of an older plant. In June, cut one away cleanly with a sharp knife without lifting the parent. Let the cut dry for a day. Sit it on a pot of half compost, half grit, with a grit collar, and keep it barely moist in light shade. It should root within a couple of months. Overwinter young plants in a cold frame and plant them out in spring.

Seed works too. Most lewisia seed needs a cold spell to sprout, so sow it in autumn in gritty compost and leave the pot outside over winter. Seedlings usually flower in their second spring. Elise seed doesn’t need the cold and can flower in its first year. Named varieties don’t come true from seed, so increase those from offsets.

Cut offsets cleanly from the parent, let the cut dry for a day, then pot them into gritty compost.

How to protect lewisia from winter wet

From November to March, keep rain off the crown but let air flow around it. Cold is not the problem. Wet is.

A pane of glass or clear rigid plastic propped 10-15cm above the plant on bricks is the traditional fix for rockeries. Leave the sides open and weigh the pane down against gales. Don’t wrap lewisia in fleece or a closed cloche, as trapped damp rots the crown just like rain. Plants set properly in a vertical wall often need no cover at all.

A cold frame suits potted plants and young offsets. Keep the lid on, prop it open a little for air, and hold back the water.

An unheated greenhouse or alpine house is the luxury option. Move pans in during October and out in late March, giving perhaps one light watering a month.

A pane of glass on two bricks keeps rain off the crown while air moves freely underneath.

Lewisia care calendar

Common lewisia mistakes

Planting it flat in open ground. A flat rosette in soil collects rain and rots. Tilt it in a crevice, or plant on a mound with a grit collar.

Watering over the rosette. A can or hose swept over the top fills the crown. Water beside the plant every time.

Rich compost and heavy feeding. Multipurpose compost holds too much water, and lots of feed makes soft, rot-prone growth. Use half grit and feed lightly.

Forgetting it in winter. One October job, fitting a pane of glass or moving the pot under cover, saves most plants.

Limy soil or mortar rubble. Lewisia prefers lime-free conditions. In chalky pockets the leaves yellow and growth stalls.

An unheated greenhouse keeps lewisias cold, dry and airy in winter, just how they like it.

Frequently asked questions

Why is my lewisia rotting?

Water is sitting in the rosette and rotting the neck. That’s the point where leaves meet root. Replant healthy pieces tilted in a crevice, or with a grit collar under the leaves, and never water over the top. Keep rain off the crown in winter.

Is lewisia hardy in the UK?

Yes, it copes with UK cold as long as it stays dry. A dry lewisia takes hard frost in its stride. Cold combined with wet is what kills it. Sharp drainage, tilted planting and winter rain cover matter far more than temperature.

Is lewisia evergreen?

Lewisia cotyledon and its hybrids keep their rosettes all year. That’s why winter wet is such a problem, as the leaves funnel rain into the crown. Some other species, such as bitterroot (Lewisia rediviva), die down after flowering and regrow later.

Should I deadhead lewisia?

Yes, cut spent flower stems off at the base. This stops the plant setting seed and encourages more flowers later in summer. Leave one stem to ripen if you’d like seed to sow.

What is the best compost for lewisia in a pot?

Half John Innes No. 2 and half horticultural grit. Top it with a layer of grit so the neck sits on stone. Avoid limy compost. Clay pans and stone troughs dry faster than plastic, which suits lewisia well.

How do you water lewisia?

Water the compost beside the plant, never over the rosette. Soak the roots, then wait until the mix has dried before watering again. Plants in the ground rarely need watering. From autumn to spring, stop almost entirely.

Does lewisia flower in its first year?

The Elise series can. It was bred to flower in its first year from seed. Most other strains, such as the Sunset Group, build a rosette in year one and flower the following spring.

Once your lewisias are settled, find more tough rockery plants in our flowers and plants hub, or add sweet-scented company with our guide to growing dianthus and pinks.