Gunnera manicata is one of the largest, most spectacular, architectural herbaceous plants grown in our gardens. Commonly known as ‘giant rhubarb’, this plant is not related to the rhubarbs at all, although it is not difficult to see how it got its common name.

The giant leaves can grow to 6ft (1.8m) or more across and are very similar in appearance to rhubarb leaves. They grow directly from the base of the plant and have strong, prickly stems. The leaves are very rough and they can make a rasping noise under windy conditions as they brush together. The flowers are hidden away among the foliage and appear in summer as green, conical spikes which turn brown when in seed.

This is not a plant for a small garden and it prefers to grow near water, so a pond or stream will provide an ideal setting. Gunnera manicata is not a completely hardy plant and needs some form of winter protection. The shoots at the centre of the plant are frost sensitive, so these should be covered with the dead leaves or a straw mulch when frost is expected.

It is important to provide a deep, rich soil for Gunnera. Add plenty of organic material to the soil and top dress every year, with more. Apart from mulching during the winter, no other attention is required.

Growing Requirements

Position
Gunnera manicata prefers an open position but it will accept a degree of light shade from tall trees. It is best grown next to water, so extra moisture should not be needed. If planted in any other location, ensure that the ground does not dry out.

Size
Giant rhubarb will grow to a height of 6ft (1.8m) with an 8ft (2.4m) spread.

Propagation
Increase plants either from seed or by splitting off a part of the plant with a spade. Plant out in the spring, after the threat of frost has passed, so that plants can become established before the onset of winter.

Family: Gunneraceae
Genus: Gunnera

Despite having an almost completely unpronounceable name, Campanula poscharskyana is a very attractive and valuable plant for the rock garden. It is a vigorous, low-growing plant with long, trailing stems bearing finely toothed, rounded or heart-shaped leaves. The plants do have a tendency to become rampant, but, fortunately, they are not too difficult to cut back.

This species of campanula makes a very good ground cover plant, especially in areas where it can spread at will. If planted among low growing shrubs, it is likely to clamber up through the lower branches. It can be grown in a rock garden, but it will need checking to make sure that it does not smother its neighbours.

Plant out in the autumn, or in spring, whenever the weather allows. These plants spread rapidly and there is rarely any need for more than one plant, unless you are using them for ground cover when you should plant them about 2ft (60cm) apart. These plants are completely hardy and will survive the winter without any problems.

This species is sometimes confused with another campanula with an unpronounceable name, Campanula portenschlagiana, which has a very similar appearance, but is less invasive and has darker, less star-like flowers.

Growing Requirements

Position
This campanula is will grow in either full sun or moderate shade and in any type of garden soil. They do best in well-drained soils and in rich soils they are quite likely to become rampant. There should be no need to water them unless there is a drought.

Size
Plants will grow to a height of 10in (25cm) and spread indefinitely!

Propagation
It is usually easy to find a few rooted stems that can be potted up to produce new plants. This is best done in spring, but can be done at any other time of the year. Campanula poscharskyana is also easy to divide.

Family: Campanulaceae
Genus: Campanula

Hops are normally associated with commercial growing for beer making but they are also grown in many gardens as attractive climbing plants. The most popular is the golden hop, Humulus lupulus aureus that has attractive golden-green leaves.

Humulus lupulus is an easy-to-grow, hardy, native climber with lobed leaves that bear clusters of fragrant, green female flowers from July to September. Make sure you buy a female plant, as male and females grow on separate plants. The leaves on the main stem are around 4 to 5in (10-15cm) long.

Plant out in spring to the same depth as it was in its pot. It may be a bit slow to get started, taking two or more years to reach its full potential. Once settled, it will set out from the ground each spring, and by midsummer will have put on 15ft (4.5m) or more of leafy growth. These plants prefer a deep, well-fed soil and don’t like to become too dry. Keep them watered in excessively dry periods.

Hops have very rough stems and leaves, which can cause painful weals, so avoid pushing through or against the plant unless your skin is covered.

Growing Requirements

Position
Although hops will accept a little light shade, they’re best to grown in full sun, especially the golden variety, as the golden colour of the foliage will turn green. They can be planted in various positions; against walls, draped over a fence or through an old shrub or tree. A tripod of poles makes an ideal support in a border setting.

Size
Hops will grow to around 20ft (6m) and spread 13ft (4m).

Propagation
Hops can be increased by taking runners that arise from the crown just below the soil surface or by dividing the roots in the spring.

Family: Cannabaceae
Genus: Humulus

Buddleja davidii is a favourite, fast-growing shrub from China. They not only make beautiful shrubs, but they also attract large quantities of butterflies to their nectar-rich flowers, which is how they derive their common name.

The fragrant flowers are borne in long spires in the late summer and early autumn, after most other shrubs have finished flowering. The most typical colour of the flowers is lilac, but there are lots of shades, varying from white to pink to deep purple. The flowers can look a little unsightly once they begin to fade and turn brown.

Buddleja are best planted out in spring, although container-grown plants can be planted out at any time, as long as the weather is not too hot or too dry. They are relatively hardy plants and will withstand most winters, although an occasional harsh one may cut them back.

Butterfly bushes must be pruned regularly, otherwise the flowers will decrease in size and the plant will tire and die. Each spring, cut back the previous year’s growth to within 3 to 4in (7.5 to 10cm) of where it started. This may seem rather drastic, but the bush will soon recover and start sprouting new growth.

Growing Requirements

Soil
The butterfly bush is an undemanding plant and will grow on a wide range of soils, including quite dry ones, as long as it is planted in a sunny position, though a little light shade will be tolerated.

Size
Buddleja will grow to a height of 13ft (4m) and spread to a similar size.

Propagation
Buddleja will self-seed and the resulting seedlings can be transplanted and used as new plants. To propagate favourite colour forms, it is essential to take cuttings from existing plants. These are best taken as hard wood cuttings in the early winter months but summer cuttings from soft, new growth can also be used.

Family: Scrophulariaceae
Genus: Buddleja

A mass planting of Bergamot can’t fail to impress. They bear curious, striking flowers in strong colours and have fragrant foliage. The leaves, when crushed, produce a wonderful aromatic perfume unlike anything else.

Although the most popular flower colour is scarlet, Bergamot comes in a wide range of colours, including pink, purple, mauve and white. The flowers are hook-shaped and appear in whorls around a dome shaped head while the leaves are oval shaped. It is quite difficult to weed around the plants, as the roots grow close to the surface.

Bergamot looks best in a herbaceous border and goes well with other plants. ‘Cambridge Scarlet’ is one of the most popular varieties and has, unsurprisingly, scarlet flowers. A similar pink-flowered plant is ‘Croftway Pink’. There is a also pure white form known as ‘Snow Maiden’.

In the winter, Monarda will be just present above the soil as a mass of small leaves. They are to be immune to frosts and require no special care. In exposed areas, the plants may need to be supported by stakes. The plants should be cut down to the ground after flowering, and mulched with manure each winter.

The leaves can be simmered in water to make a refreshing bergamot tea. The flowers have a similar scent to that of the bergamot orange (which is used to flavour Earl Grey tea), hence the plant’s common name.

Growing Requirements

Soil
These plants like full sun or very light shade and will thrive in most types of soil, except in clay or where the soil is very dry. They will need to be kept well-watered over the summer.

Size
Bergamot can range in height from 3ft to 5ft (90cm to 1.5m) with a spread of around 18in (45cm).

Propagation
Monarda can be divided in the spring, as they start growing. This will rejuvinate old clumps and provide new, vigorous plants. Cuttings can also be taken when the plant is producing fresh and vigorous growth.

Family: Lamiaceae
Genus: Monarda

Agapanthus plants are native to South Africa and were introduced into Europe in the seventeenth century. The most commonly grown varieties are the Headbourne hybrids, which are available in an array of blue shades. White varieties can also be grown but don’t have the same impact as the deep blues.

The round balls of the agapanthus blooms provide a late summer spectacle. The intense, blue flowers can provide a focal point in a border or a tub, or they will mix well with a range of other plants. Deciduous Agapanthus are generally hardier than the evergreen ones but both will tolerate a light frost.

Agapanthus love full sun but they have been successfully grown in light shade. Headbourne hybrids are hardy, but some of the other species and hybrids will also come through most winters. The problem is winter wet as much as cold. Covering the plants with a sheet of glass to keep them reasonably dry, while allowing air to circulate to prevent condensation, will help.

These plants require little attention other than to tidy up the rotting leaves and flower stems during the early winter. They will rarely need staking. If you don’t mind sacrificing a few stems, they make good cut flowers from the house.

Growing Requirements

Soil
These plants like a moist, free-draining soil, but will grow well in a dry soil that has had organic material added. They thrive in deep, fertile soils but will tolerate quite poor soil.

Size
Agapanthus can reach a height of 3ft (90cm) with a spread of around 2ft (60cm).

Propagation
Dividing existing plants in spring is the easiest way to increase them. This must be done carefully, as the roots are brittle and resent being disturbed. They are best planted out in spring and should be placed about 18in (45cm) apart.

Family: Agapanthaceae
Genus: Agapanthus

Salvia splendens is really a perennial from Brazil, but it is most often used as an annual bedding plant in northern Europe. It is fast growing and flowers in the first season after sowing. They can be used in all sorts of areas as they are happy in tubs, window boxes and other containers, and can be more formally planted in bedding displays.

The most common cultivar used is the brilliantly scarlet ‘blaze of fire’ but other varieties are available in pink and purple shades and in sizes between 8in and 24in (20cm to 60cm) tall. The flower colour of salvia is a combination of flowers and bracts. Plant well grown plants outside only when all risk of frost has passed. Salvias are very frost tender, and a frost can decimate a newly planted scheme overnight. Always select sturdy and multi-stemmed plants and deadhead the plants to keep them tidy and to encourage continuous flower production.

Plants grown in the open ground will usually need no additional watering after planting. Container plants are more vulnerable to drying out and the compost needs to be kept moist. In cooler climates, they can be planted in full sun but in areas that get very hot summers, partial shade will be required.

Growing Requirements

Soil
Salvia splendens prefers a fertile, free-draining garden soil, but pot-grown plants will grow well in a good quality compost. Container grown plants will need feeding every 7 to 10 days, from planting out to the end of the season, with a proprietary liquid plant food.

Size
Height around 12in (30 cm) with a similar sized spread.

Propagation
Propagation is by seed. Sow the seed under glass between January and March, where a temperature of 20 to 27° C. is required for germination to occur. Grow on at around 13° C. and plant out after the danger of frost has passed.

Family: Lamiaceae
Genus: Salvia

Yucca Gloriosa delights in having several descriptive common names – Spanish dagger, Adam’s needle, palm lily and Roman candle. It is an evergreen shrub, but is often considered to be a hardy perennial by gardeners. In colder districts, they will need be grown in tubs and over wintered under cool glass.

The plants have an exotic appearance, a tall, conical flowering spike, erupting from a base of sword-like grayish, green leaves, which immediately catches the eye. They make excellent plants where a focal point is needed or they can be used as an accent plant in a border. The flower spike appears in late summer, and carries an abundance of creamy-white, cup-shaped flowers, sometimes edged with crimson.

Apart from cutting off any dead foliage, or fading flower stems, Yucca Gloriosa needs little attention. Young plants, or offsets, should be planted out in spring, so that they have a full growing season before facing a cold winter. The ends of the leaves have very sharp spines so this needs to be considered if children play in the garden.

Growing Requirements

Soil
Well-drained soil is required but it does not need to be rich, as palm lilies will grow in quite poor conditions. They can withstand drought, so there should be no need to water after the plant is established.

Size
Yucca Gloriosa will grow to a height of around 6.5ft (2m) with a spread of 4ft (1.2m). The leaves are around 2.5ft (75cm) long and 2in to 3in (5cm to 8cm) wide.

Propagation
Sow seed in spring under gentle heat. Root cuttings can also be taken in winter, by cutting one or more of the thick roots into 2in (5cm) sections and placing them in compost. Another method is to remove some of the offsets from around the edge of the plant and pot them up.

Family: Agavaceae
Genus: Yucca

Cornus kousa var. chinensis was introduced from China in 1907 and differs from typical Cornus kousa in its taller, more open habit, usually forming a small tree. Despite having long-lasting pretty flowers, good autumn colour, an ability to blend well with other plants and a comparatively small size, the Chinese dogwood is not seen too often, even though it is easy to find in garden centres and nurseries.

The flowers are the most intriguing feature of this tree. They are very small and would be inconspicuous if it were not for the four white bracts (leaf-like attachments) that surround them. Because they are bracts, and not petals, they remain in flower for a very long time. They start white, but become flushed with pink as they age.

The leaves are a bright, fresh green colour, which sets off the flowers well. In autumn, they turn a wonderful range of oranges and reds. This tree is quite hardy and should survive most winters easily. Apart from removing any dead or damaged, wood, no pruning is required.

Growing Requirements

Soil
Cornus kousa var. chinensis is best grown as a specimen tree. It will grow well in a fertile, humus-rich, soil, located in full sun or partial shade. It is not recommended for growing in poor, shallow, chalk soils. It prefers an acid to neutral soil but can be grown in slightly alkaline conditions.

Size
The Chinese dogwood can grow to a height of 20ft (6m) and spread to around 15ft (4.5m), though in the average garden, 12ft to 15ft (3.5m to 4.5m) is the more likely ultimate height.

Propagation
It propagates well from seed, which should be cold stratified when ripe and then sown the following spring. It can also be propagated by taking cuttings in the summer.

Family: Cornaceae
Genus: Cornus

Michaelmas daisies are beautiful, tough, herbaceous perennial plants that are easy to grow and look after. The daisy flowers are bright and cheerful, which provide a useful splash of colour at the end of the year. Their colours are mainly restricted to pinks and purples, though the range of shades seems almost infinite – they vary from soft pink to nearly red or blue. There are also white forms.

These plants will grow in a wide range of soils, even poor ones, but they do best where there is humus in the soil to retain moisture. Michaelmas daisies can be planted at any time of the year as long as they are watered well before lifting and again after planting.

Aster amellus do not like damp areas, but they also dislike soil that dries out and are likely to suffer mildew in such conditions. Water regularly during dry spells and deadhead regularly to prolong flowering. The stems of these plants don’t normally need support, except in windy areas where they may require staking. The cold shouldn’t present any problems during the winter.

Growing Requirements

Position
While they will grow in light shade, Michaelmas daisies will always do best in full sun. If they are planted under trees or against a north wall, they become drawn and often suffer from mildew. They are best in an open site, where air can circulate freely which will help to avoid mildew problems

Size
Michaelmas daisies vary in size and can reach a height of 1ft to 4ft (30cm to 1.2m) and spread about 2ft (60cm).

Propagation
Propagation is easily achieved by division in the spring. They can also be grown from seed. Sow the seed in spring. Germination can be improved by chilling.

Family: Asteraceae
Genus: Aster