Wallflowers: planting, pruning & overwintering

Wallflowers come in a vast array of colours, bringing variety to gardens as early as spring. Find out everything you need to know about these spring bloomers.

Wallflowers (Erysimum cheiri syn. Cheiranthus cheiri) bless us with an abundance of colourful flowers from early spring until July. For more than a century, wallflowers have been common ornamental plants, especially in peasant and monastery gardens. Read on to learn how to properly care for this traditional, fragrant flower.

Wallflower: origin and characteristics

Wallflowers originate from southeastern Europe and belong to the cruciferous family known as Brassicaceae. They are widespread throughout the Mediterranean region and feel at home on rocky surfaces and walls. Today, the colourful wallflower can still be found in home gardens and as an ornamental balcony plant.

Wallflowers flower from early spring to July, but some hybrids bloom into September. The flowers range from yellow, orange and white to purple tones. Depending on the variety, wallflowers grow between 20 and 60cm high. The inflorescences consist of 10 to 30 flowers, which form clusters on the stems.

Are wallflowers perennial? Wallflowers are biennials, meaning they last for two growing seasons. They typically die after blooming in their second year. In wind-protected and warm places, the plants can also lignify and live for several years in a garden.

Wallflower varieties

Crossbreeding wallflowers with other wallflowers produces beautiful varieties. Some such varieties are:

• ‘Auroraˈ: salmon-pink flowers with pink veining; 45cm tall; biennial; moderately hardy
• ˈApricot Twistˈ: bright orange flowers; 20 – 30cm tall; perennial
• ˈBowles Mauveˈ: dark purple flowers; 50 – 70cm tall; perennial; hardy
• ˈRufusˈ: pink-yellow flowers; up to 50cm tall; perennial; hardy
• ˈConstant Cheerˈ: orange flowers that turn purple; 30cm tall; perennial
• ˈIvory Whiteˈ: white flowers; 40cm tall; biennial
• ˈPlant World Lemonˈ: yellow-purple flowers; 20cm tall; perennial

Growing wallflowers

Wallflowers like sunny, warm and sheltered spots on nutrient-rich, well-drained, dry and calcareous soil. They do not tolerate waterlogging or acidic soils. Whilst wallflowers do cope well with drought, they do not tolerate heat. These plants often grow individually or in small groups. In favourable conditions, wallflowers can self-seed and propagate themselves.

Plant wallflowers from May to June to have them ready and flowering by the following spring. Wallflowers can only be grown as perennials if kept in pots with very good drainage. You will also need to overwinter them in a frost-free place or keep them in mild conditions. Keep reading to find out how to overwinter wallflowers later in this article.

Sowing wallflower seeds

The best time for sowing perennial wallflowers outdoors is between May and July. To do this, prepare a fine-grained seedbed in a warm, sunny location. Our Plantura Organic Herb & Seedling Compost is ideal as a substrate, as it provides sufficient nutrients as well as a loose structure for optimal root development.

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Once the soil is ready, sprinkle the seeds in rows on the soil. Cover the seeds with a little substrate, lightly press the soil down, and water. The seeds germinate best at a temperature of 15 to 20 °C. Once the young plants have more than four leaves, prick them out and pot up or plant out.

Planting wallflowers

The best time to plant perennial wallflowers is either in the autumn or the following spring, starting in March at the earliest. Tend to your wallflower seedlings in the first year, and plant them out to bloom in the second year. Keep a planting distance of 30cm. Wallflowers can be planted directly outdoors in temperate regions. In areas with harsher winters, opt for a flower pot instead. Normal potting soil, such as our Plantura Organic Flower Compost, is suitable as a substrate. Our soil contains compost, lime, magnesium fertiliser as well as an organic fertiliser to provide your wallflowers with a well-balanced range of nutrients. It is ideal for both potted and bed plants. If you want to plant the wallflower in a pot, it should be able to hold at least 3 litres. As wallflowers do not tolerate waterlogging, create a drainage layer in gardens with heavy and dense soil. Loosen the soil well before planting.

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Wallflower care

Wallflowers are low maintenance plants that require little care. Note that Erysimum cheiri is poisonous, so always wear gloves when working with these plants.

Watering and fertilising wallflowers

Once wallflowers have established themselves in the bed, they rarely need watering. Potted wallflowers, on the other hand, need to be watered regularly. Although wallflowers tolerate drought well, you need to ensure they get enough water during the flowering period. Never let wallflowers dry out completely, even in winter. That said, you will need to water much less frequently during the colder months.

Fertilising with horn meal at the beginning gives the bed plants strength in the spring. After the initial feed, fertilise wallflowers in the bed once a month with a liquid fertiliser. When growing wallflowers in pots, apply fertiliser every two weeks from March to June. Our Plantura Liquid Flower Food is a liquid fertiliser that is suitable for wallflowers. It is easy to apply by diluting into the water you use for watering and promotes healthy plant growth.

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Pruning wallflowers

Wallflowers tolerate pruning. Deadheading regularly can help to extend the flowering period. To encourage your wallflowers to grow more densely, start pruning young plants once they reach 10cm high.

Are wallflowers hardy?

Whether wallflowers are hardy depends entirely on the variety and the location. In any case, we advise covering them with brushwood during the winter to protect them from frost. Bring potted wallflowers indoors for the winter. When overwintering wallflowers, put them in a bright, frost-free place and water them from time to time. Do not let them dry out completely. That said, excessive moisture and poor drainage can make your wallflowers more susceptible to diseases, which could lead to dieback over the winter.

Wallflower propagation

Wallflowers spread by self-seeding. To harvest wallflower seeds, remove the pods before they burst open. Then follow the previous instructions on sowing wallflower seeds. As biennials, wallflowers form a rosette of leaves in the first year, and then flower in the second year.

It is also possible to propagate wallflowers by cuttings. To do this, cut off young, non-flowering and non-woody shoots in early summer and put them in growing soil, such as our Plantura Organic Herb & Seedling Compost. Keep the tips of the shoots moist by misting them with water occasionally. If necessary, cover the tips of the shoots with a plastic bag to keep the humidity high and consistent. Just remember to air out the bag once a day to prevent mould. Then plant the young wallflower plants out in autumn.

Tip: you can use the cuttings from pruning for wallflower propagation too!

Are wallflowers toxic?

Wallflowers contain cardenolides, which make the seeds especially poisonous. If ingested, they can lead to nausea and vomiting and, in the worst case, even cardiac arrhythmias. For this reason, wallflowers are certainly not edible. Take care to prevent accidental consumption, especially by children. Wear gloves while gardening or remember to wash your hands afterwards. Wallflowers are also toxic to cats and dogs. For cats, even small amounts can be fatal.