Wisterias are one of the most stunning ornamental climbing plants and are grown for their beautiful, scented pea-flowers produced in late spring and early summer. They are available in a range of colours including white, blue-violet, deep purple and pink or apricot. They are usually vigorous plants and are ideal for high walls and fences or pergolas and arches where the flowers can hang down. They can also be for clambering up large trees although this can make pruning of the wisteria difficult and the flowering may be affected by a dense tree canopy. The most magnificent wisteria displays that I have seen have been on a trained espalier form and this is one of the best suited to display the flowers.

Most wisterias are fully hardy, but they flower best in a warm, sunny, sheltered site. They are very hungry plants and need to be planted with a large amount of organic matter to enable them to flower freely. Mulching is also recommended and you can use either garden compost or well-rotted farmyard manure. Feeding should be done before flowering in the spring with a slow release fertiliser such as growmore, fish blood and bone, or a rose fertiliser. After flowering, the next years flower buds will begin forming from July onwards so it is important to keep the roots moist during dry spells between July and September, as drought at this time can result in your wisteria failing to produce any flowers for the following year.

If you have a wisteria that has failed to flower for a number of years, it could be worth testing the soil to see if it is alkaline. If it is then this can be rectified by adding a small dressing of iron sulphate and this will help the soil to become slightly acid and may encourage your wisteria to flower.

Seed raised wisterias take longer to flower than grafted plants so it may be better to choose a plant that you can see the bulge of the graft union near the base of the stem. Named cultivars are almost always grafted, where as species plants may not be. Wisteria sinensis produces its flowers before the leaves appear which can look spectacular and Wisteria floribunda bears the leaves and flowers at the same time.

Prune wisteria in mid-winter and again in the summer approximately two months after it has finished flowering. The aim of pruning is to keep it floriferous and to prevent it from growing out of its allotted space.

In January or February cut back the side shoots to within one or two inches (or 2 - 3 buds) of the older wood. This will tidy up the plant before the growing season begins and will ensure that the flowers will not be obscured by leaves.

In July or August cut back the whippy new growth to five or six leaves (or about 1 foot). This encourages the plant to form flower buds rather than green growth and also controls the size of the wisteria and prevents it twining around other plants or guttering etc. This can be an ongoing process until the plant becomes dormant and any long shoots that grow after the summer pruning should also be removed.

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