How to plant, grow & care for wallflowers

How to plant, grow & care for wallflowers

Wallflowers are one of my favourite flowers, ranging from the most wonderfully rich colours to smokey pastels, with swoon-worthy scent. They are best planted in blocks and drifts for maximum impact, rather than dotted in threes and fours. Luckily they are super easy to grow from seed so you can add a huge number of plants to the garden each year.

Most wallflowers are biennials, meaning that sown from seed, the plant will spend its first year establishing its roots and foliage, and it will go on to flower, set seed and die in its second year. Biennial wallflowers are brilliant as spring and summer bedding, particularly when grown with tulips or other bulbs, bringing colour to the garden from March.

There are also perennial wallflowers, which can be extremely long-flowering, returning year after year with very little effort, though some can be short-lived. ‘Bowles Mauve’ is a famously good perennial wallflower, a rich and fabulous purple and very long-flowering from March to July and intermittently for most of the year.

Details Where & when to plant How to sow How to plant Care guide Pests, diseases & common issues Frequently-asked-questions

Details

Calendar

Jan J

Feb F

Mar M

Apr A

May M

Jun J

Jul J

Aug A

Sep S

Oct O

Nov N

Dec D

Sowing

Planting

Flowering

Where & when to plant

Where to plant

Soil type

Moist, well-drained soil is best for wallflowers. If you have heavy clay soil, add grit to the planting hole to improve drainage. They can survive in quite poor conditions and can be seen growing out of stone walls in cottage gardens – it’s from this they were given the common name of wallflowers.

Aspect & position

Wallflowers need a position in full sun, though some can tolerate part shade.

When to plant

Sow seeds undercover in February-March, or sow outside in April-May. Young plants can be moved to their final position in late-summer and early autumn to flower the following year.

How to sow

Wallflowers are really easy to grow from seed. The sowing time can vary depending on the wallflower, so check the seed packet.

If sowing undercover, sow seed thinly in a seed tray and cover with a fine layer of compost. Prick out into 7.5cm (3in) pots when large enough to handle. You can also sow them in Jiffy 7s. Young plants should be in their final positions by August and September.

If you’re sowing wallflower seeds outside in late spring, sow in rows. Once the seedlings are up, thin out plants to 15cm (6in) apart and transplant to their final positions in autumn.

Alternatively, you can leave them where they were sown and then – watering well before and after – move them to their final positions in early March. They should then grow away well.

However you choose to sow them, make sure to water them in and label them. Pinch out the growing tips once you have three pairs of true leaves to encourage bushiness.

Photography by

Jonathan Buckley

How to plant

Whether you’ve grown your wallflowers from seed or bought them as young plants, the important thing is to get them into their final position in the garden by the end of August or September.

In late August the soil is still warm, but the dews have started falling good and thick. The ground is therefore moist enough to not need watering. The roots rocket away and the plants are well established and strong before the nights become very cold in October.

Newly planted wallflowers can be mulched with a 5cm (2in) layer of mushroom or garden compost to help retain moisture in the soil and suppress weeds.

Photography by

Jonathan Buckley

Care guide

Watering

Water in newly planted wallflowers. Water during a prolonged dry period and keep a close eye on wallflowers in containers.

Fertilising

Wallflowers don’t need any extra food. However, newly planted wallflowers can be mulched with a 5cm (2in) layer of mushroom or garden compost to help retain moisture in the soil and suppress weeds.

Staking

Taller varieties of wallflowers grown without any support tend to lurch over to one side in the wind and rain and then start to grow upwards from their hip. That is one drunken lurch you don’t want. Get them growing straight up and you immediately gain wonderful height.

If you are growing a block of wallflowers, spread pea or jute netting horizontally over the whole block in one go, tying it on to canes at each corner. Stretched taut over all the plants at a height of about 20cm (8in) should ensure lovely upright wallflowers, and their foliage will soon cover the netting.

Deadheading

Biennial wallflowers should be deadheaded to prolong the flowering period. It’s not so important when the weather is cold, but as soon as you get a few hot days, they can set seed quickly.

Perennial wallflowers should be deadheaded as the flowers fade.

All wallflowers make wonderful cut flowers, so pick them to enjoy indoors.

Propagating

Biennial wallflowers should be grown from seed – they may also set seed, but are unlikely to come true to the parent plant. Perennial wallflowers can be propagated by cuttings.

Pests, diseases & common issues

Flea beetle

Flea beetle is a pin-head-sized, shiny, black beetle, which hops about like a flea. You’ll know flea beetles are feasting on your wallflowers if the leaves are peppered with small holes.

Mature plants should be fine, but they can be a problem with young seedlings; the holes they create are not enough to kill young wallflower plants, but it holds them back several weeks.
If you have trays or rows of young plants, try holding sticky fly paper over the lot, then have someone ruffle the leaves of every plant. The flea beetles hop up on to the paper and stick! You can also try companion planting with a mustard plant, which attracts the flea beetles away from the wallflowers.

Why is my wallflower dying?

A very wet and cold winter might impact wallflowers, or new shoots in early spring may be singed by frost. If there is still life in the plant, pinch off the tips or cut back to encourage new growth. If you anticipate extremely cold or wet weather, cover the plants with horticultural fleece or a cloche.

What can I do with old wallflowers?

You can lift spent biennial wallflowers planted as bedding and compost them. If you deadhead regularly, it will help prolong the flowering period.

Do slugs eat wallflowers?

Slugs don’t seem particularly interested in wallflowers.

Photography by

Jonathan Buckley

Frequently Asked Questions

When do wallflowers flower?

Biennial wallflowers spend their first year establishing roots and foliage, and go on to flower, set seed and die in the second year. Flowering time is usually from March into summer.
Are wallflowers poisonous?

Wallflowers contain the chemical compound cheiranthin, which can be toxic. But many wallflowers have been deemed non-toxic to dogs, other pets and humans.
Do wallflowers grow every year?

Many wallflowers are biennial and will only flower for one season, however some wallflowers are perennials, such as ‘Bowles Mauve’ and will come back year after year.
Are wallflowers perennial?

Some are short-lived perennials and some hardy perennials. It’s a good idea to take cuttings of perennial wallflowers in case of losses.
How long do wallflowers last?

In a vase, wallflowers can last 5 days or up to a week.
Do wallflowers self seed?

Biennial wallflowers can set seed, but the seed is unlikely to come true to the parent plant.
When to cut back wallflowers?

Deadhead biennial wallflowers throughout flowering. Perennial wallflowers can be deadheaded once the flower has faded.
Do wallflowers like sun or shade?

Wallflowers need a position in full sun to thrive.

How to cut and arrange wallflowers

Most wallflowers will give you 5-7 days in a vase, which is fantastic. Sear stem ends in boiling water for 10-15 seconds before plunging into cold water. Add a slosh of clear vinegar in their vase water to keep them going as long as possible.

I love arranging them with other spring-flowering plants. Purple honesty, another biennial, stipa and tulips make a fantastic combination. I pick these four and put them together in a vase for a rich, velvety, incredibly fragrant combination – what more can you want from flowers?

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Rich Velvet Wallflower Collection

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Erysimum 'Winter Orchid'

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Erysimum 'Red Jep'

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Common name	Wallflower
Latin name	Erysimum
Type	Perennial / Hardy Biennial
Height	25cm (10in) to 75cm (30in)
TLC rating	Easy
Aspect	Full Sun
Planting position	Borders, Containers
Suitable for pots	Yes
Good for pollinators	Yes
Good for cut flowers	Yes