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Home & garden.

Updated: 13 Jan 2022

How to grow violas

Fill pots and summer borders with the long-lasting scented blooms of violas. Discover our best viola varieties and tips for how to grow them
CT
Ceri Thomas
Violas

Huge numbers of pansies and violas for winter containers are sold every year to gardeners who love their colourful blooms. Summer-flowering perennial violas, on the other hand, are much less widely grown. Yet they’re a great choice for the summer and will earn their place in your garden with an incredibly long flowering period, delightful blooms and lovely scent, plus they will grow back year after year.

Which? Gardening magazine grew a range of popular varieties in the north and south of the UK to see which would give us the best display.


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Key facts

PLANT TYPE Herbaceous perennial

POSITION Full sun or part shade

SOIL Moist but well-drained and humus-rich

How to grow violas: month by month

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JulyAugustSeptemberOctoberNovemberDecember
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Best viola varieties

Which members can log in now to see the full results and which are our Best Buy varieties. If you're not a member, join Which? to get instant access.

Best Buy violas
What it looks likeVariety nameHeight x spread
25 x 40cm
This variety grew very quickly into big clumps. In north London, the growth became a bit wild-looking in mid-summer and a couple of the plants flopped out from the centre, but they responded well to being trimmed and were soon back in full flower. They had a light but deliciously sweet and very noticeable scent, and the luminous colour of the flowers showed up particularly well on duller days. This variety holds an RHS Award of Garden Merit (AGM). Peak flowering: April-September
What it looks likeVariety nameHeight x spread
20 x 35cm
Smothered with delicately coloured blooms, this variety really was a delight to grow. The flowers had a lighter scent than some of the others in our trial, but it was sweet and carried well in the air. All the plants grew well throughout the trial in both the north and the south. They kept their shape for a long time and were very healthy, coping particularly well with the heat of north London, where they flowered for slightly longer than in Northumberland. Peak flowering: May-August
What it looks likeVariety nameHeight x spread

How we test violas

We chose 21 different varieties, including the most widely sold and well-known varieties. We also included a few newer varieties. We grew five plants of each variety at the Which? Gardening magazine trial garden in Capel Manor, north London, where the weather is mild with moderate rainfall, and at Alnwick Gardens in Northumberland, which has similar rainfall to north London but is colder in winter and cooler in summer. We assessed all varieties over two years. In autumn of the first year, we cut the plants back to around 5-7cm to encourage fresh growth. We watered the plants at times during the hot, dry summer. They were assessed for: flowering duration, scent and how good the overall the display was; how well they grew over two years and whether they became straggly; and how susceptible they were to common viola problems.

Caring for your plants

Planting

Plant in sun or part shade into well-drained soil that doesn’t dry out in summer. Violas also grow well in pots filled with a Best Buy compost for containers mixed with Best Buy controlled-release feed.

Watering

Water them during any long dry spells of weather in summer to prevent the soil drying out. Water daily if growing in pots.

Deadheading

In July, straggly plants can be lightly trimmed with shears to take off the top 2-3cm of growth. In autumn, when flowering has finished, cut plants back to around 5cm high.

Feeding

Plants grown in reasonably fertile soil shouldn’t need feeding. In poor soil, feed with a general fertiliser in spring. Either add controlled-release fertiliser to containers at planting time or liquid feed fortnightly with a high-potash feed such as tomato food

Common growing problems

Slugs

Slugs target new growth in spring. Pick off any you find and use organic pellets containing ferric phosphate to keep them at bay.

Read more about slugs.

Aphids

Aphids often attack the early growth in spring. Check the base of the plants, where they tend to hide, and squash any that you see to prevent them getting established.

Read more about aphids.

Leaf spot

Fungal diseases causing black leaf spots and downy mildew are common on perennial violas. Remove affected leaves and stems if you see them. Fungicide sprays can help with leaf spots, but not downy mildew. Don’t replant violas where badly affected plants have been grown before.