Wallflowers are beautiful, sweetly fragranced flowers that come under the brassica plant family. These spring flowering plants are typically grown as biennials, though less common perennial varieties do offer continued blooms year after year. Wallflowers are easy to grow and are highly rewarding in looking stunning when blooming in spring. They’re also a great source of nectar as pollinator-friendly plants.
In the below guide, we cover everything you need to know about how to grow wallflowers, with tips on sowing, planting, and caring for your wallflower seeds and wallflower plants.
Ground Prep
You should choose and prepare the area for your wallflowers before planting. Remove any weeds, dig in garden compost or well-rotted manure, add a dressing of a balanced garden fertiliser, and break the soil down to a crumbly texture to create the best growing conditions for your flowers.
Your wallflowers should be grown in a full sun spot in well-drained soil for the best chance of successful growth. They are capable of growth in many types of soil, though they do slightly prefer alkaline soils.
Sowing
When to Sow Wallflower Seeds
Wallflower seeds should be sown between late spring and early summer, which will then blossom in the following spring as biennial plants. However, they can be sown earlier under cover between February and March.
How to Sow Wallflower Seeds
You can sow wallflower seeds either indoors or outdoors. Sowing outdoors is a little more straightforward, whilst sowing indoors gives the benefit of a more controlled environment.
Sowing Wallflower Seeds Indoors
If sowing indoors, sow your wallflower seeds in seed trays in quality garden compost. They tend not to germinate well at higher temperatures, so aim to keep them at around 15°C (59°F). To maintain ideal growing conditions, either use a garden propagator or keep them in a clear plastic bag. Your seedlings should then germinate in 7 to 14 days.
Once your seedlings are large enough to handle, you should transfer them to individual pots and continue to grow them on within a cooler environment. Afterwards, they can then be transferred to their final positions outdoors.
Sowing Wallflower Seeds Outdoors
To make things a little easier, you can sow wallflower seeds directly outdoors. Sow them thinly in a sunny spot in well-drained soil. They should be sown 15mm (0.6in) deep, in rows 30cm (12in) apart. Cover your seeds with soil and ensure you water them in well.
Depending on your preference, you can either transfer them to their final positions when they’re large enough to handle in autumn or in early March.
Planting
When to Plant Wallflowers
Bareroot wallflowers are autumn-planting flower plants, ready to bloom in spring. Similarly, biennial wallflowers grown from seed can be planted out around late summer to early autumn, which will then flower the following spring. Perennial wallflowers should be planted between May and September for spring blooming.
Just be sure to avoid planting when soils are too wet or frozen, as this can either severely affect the growth of or kill your wallflowers.
How to Plant Bare Root Wallflowers
When you receive bare-root wallflower plants, first unpack your order immediately and stand upright. It is important to plant them out in the garden as soon as possible, spreading out the roots and firming the soil into good contact with them.
If you are unable to plant out immediately, temporarily heel the plants in. It’s important to keep the roots moist at all times.
Plant in a position that receives lots of sun in well-drained, humus-rich soil. Leave around 25-30cm (10-12in) between each plant. Water in well and keep the plants moist until they are well established.
Planting Wallflowers in Containers
Wallflowers can also be successfully grown in containers and baskets. These are best planted in loam-based compost, as these typically contain a form of slow-releasing fertiliser. However, additional feeding is necessary once this is exhausted. Adding in water-retaining gel granules will also help in reducing the amount of times you need to water them.
Plant Care
Watering
Keep all plants well-watered until they are fully established, taking extra care to water them if the weather is dry in the months after planting. Established plants will vary in their need for watering.
Wallflowers planted in containers should be watered more often, as these are more susceptible to drying out.
Feeding
Regularly feeding your wallflowers with a liquid garden fertiliser will help to encourage bushier growth.
Deadheading
Make sure to deadhead your wallflowers during flowering season, as this will encourage further blooms.
Staking
Some varieties of wallflower can grow quite tall, so they will benefit from staking to help keep them upright and prevent damage from wind or rain.
Pinching Out Tips
For extra bushy plants, pinch out the growing tip after planting. This will also protect any late growth that may be hit by frosts. In January/February, remove any side shoots that have become damaged over the winter.
Problems
Growing wallflowers is generally trouble-free, though there are a couple of known issues that may arise. Below are the most common problems when growing wallflowers and ways to either prevent or resolve these:
-
Slugs and snails: Slugs and snails can attack wallflower plants and cause damage over time if not kept on top of. So, using slug and snail control products is useful for deterring or killing these pests.
-
Downy mildew: Downy mildew is a disease caused by a fungus-like organism, occurring in wet, humid conditions. It can appear in many different ways on plants, with the predominant sign being discoloured blotches on foliage (which are often yellow).
Ensuring good air circulation between plants and avoiding getting leaves wet when watering are ways to prevent the problem from arising. Affected leaves should be removed immediately, whilst severely affected plants should be burned or binned.
- Flea beetles: Flea beetles will feed on the foliage of wallflowers, leaving small holes in leaves. They can be tolerated on mature plants, though they can stunt the growth of seedlings. Using garden netting to keep them out, or growing mustard seeds (found under our green manure seeds) as a companion plant to attract them away from your wallflowers are two useful methods.
- Clubroot disease: Wallflowers can be affected by clubroot, which is a disease that causes plants to develop severely distorted and swollen roots. This then causes them to suffer from poor nutrient and water absorption and poor growth.
Clubroot cannot be chemically removed, so acting proactively rather than reactively is the best method. This includes raising the pH of your soil, growing seeds from trusted providers and practising good garden hygiene. For more information on clubroot, read our guide on how to prevent clubroot disease.
Shop Wallflowers at D.T. Brown
After finding out all of our best tips on how to grow wallflowers, you can get started on producing your own vibrant blooms by shopping our wallflower seeds and wallflower plants at D.T. Brown. We’ve been providing gardeners with quality flower seeds and flower plants for over a century, so you can trust our varieties to grow reliably and provide excellent colours.
You can find many more tips to keep your garden at its best in our garden blog, with many more growing guides like this one offering our best advice.
If you’d like to learn more about our range offlower seeds, herb seeds, garden accessories, or anything else in our collection, get in touch with us today and we’ll happily answer any questions you may have.
