Plants for Rooftop Gardens (Growing on a Windy Site)

In this article, plants there are suitable to be grown in rooftop gardens will be discussed. Rooftop gardens tend to get a lot of sunshine but are also exposed to extremely windy conditions. In order to do well under these conditions, you need plants that are happy basking in the sun, but also windproof, and can be grown in containers.  This is not an easy task to meet but with the correct selection, it is possible to have plants throughout the year.

Most rooftop gardens are container gardens by nature, as this makes it easier to move around. Remember most roofs have weight restrictions, so you need to opt for lighter containers made from galvanized (rust proof) metal or UV protected plastic. You can also consider wooden troughs or half-barrels for a more rustic design.

Sun and wind can be damaging to plants, as the compost that they are in, will dry quickly, especially in the height of summer. You will need to use an automatic watering system or watering spikes.

Despite these limitations, you have plenty of shrubs and small trees to give height and shade to your container garden. Roses, perennials, and annuals will give colour to romantic scheme, and phormiums and grasses to give leaves to complement modern designs.

You will also need to use more hardy plants in order to avoid frost damage, which will be prevalent in winter in rooftop container gardens. The following plants make ideal specimens in rooftop gardens, and will thrive:

AGASTACHE AURANTIACA (Giant Hyssop)

This 50cm tall upright perennial has grey-green, scented leaves, where mid to late summer, it has long-lasting spikes of small, tubular blue flowers. Plant it in a group in a large container full of multipurpose compost. Look out for ‘Apricot Sprite’

ANTHEMIS TINCTORIA (Dyer’s Chamomile)

In summer this clump-forming perennial of finely, cut, green leaves, is covered with masses of daisy-like, white or yellow flowers held on slender stems. Plant in a large container of moisture retentive multipurpose compost where it will grow up to 1m in height.

ARMERIA MARITIMA (Thrift)

This mound-forming perennial has grass-like, green leaves, where in summer it is dotted with small, round white or pink flower heads appear. This small perennial only grows up to 10cm in height, where it can be grown in small containers of multipurpose compost.

ARTEMISIA (Wormwood) ‘Powis Castle’

This subshrub, with its fern-like, silvery-grey leaves, makes an excellent foil to other plants. The clump-forming plants produce yellow pompon-like flowers in summer but are too distractive. It is best to remove the flowers to retain the silvery foliage effect. Grow in a large container full of multipurpose compost, where it will grow up to 1m in height.

BUXUS SEMPERVIRENS (Box) ‘Suffruticosa’

This familiar slow growing, compact evergreen shrub, has woody stems of small, oval, green leaves. Ideal for topiary, where they can be clipped to any desired shaped. Grow in a large pot full of moisture retentive soil-based compost, where it will grow up to 1m in height.

CALAMAGROSTIS x ACUTIFLORA (Feather Reed Grass)

This is a deciduous, clump-forming grass that has long, arching, green leaves. In summer, tall, bronze flowers appear, where the seed heads give winter interest. Grow in a large pot of multipurpose compost where they will grow up to 1.8m in height.

CHAMAECYPARIS OBTUSA (Hinoki Cypress) ’Rigid Dwarf’

A compact, dwarf evergreen conifer, makes a cone of dark green leaves that acts as a focal point. Plant it in a large pot of soil-based compost, where it will grow up to 1.2m in height.

CHAMAECYPARIS PISIFERA (Sawara Cypress) ‘Plumosa Compressa’

An irregular shaped slow growing dwarf, evergreen conifer. The leaves turn sulphur yellow in winter and so add extra interest. Grow with other small shrubs and bulbs in a large container of soil-based compost, where it will grow up to 1.2m in height.

CLEMATIS MACROPETALA (Downy Clematis)

This 3m tall climber has mid-green leaves that are divided into leaflets. From late spring into early summer the clematis is covered with semi-double, mauve-blue flowers, which is followed by atypical fluffy seed heads. Grow it in a multipurpose compost in a large container. Clematis appreciates having their heads in the sun but their roots in the shade.

CORYLUS AVELLANA (Corkscrew Hazel) ‘Contorta’

This bushy, deciduous shrub has oval mid-green leaves. This centrepiece plant is grown for its distinctive contorted stems. Pale yellow catkins forms on bare stems in late winter. Grow in a very large pot of multipurpose compost.

CROCOSMIA MASONIORUM (Montbretia)

This perennial has arching, sword-shaped dark green leaves that are pleated lengthways. In late summer, orange-red flowers on wiry stems appear that last for several weeks. Plant in large containers in a multipurpose compost in a predominant location.

ERIGERON KARVINSKIANUS (Mexican Fleabane)

This is a low growing perennial, only growing up to 15cm in height. It has a spreading habit which has lance-shaped hairy, green leaves., where in summer flowers that are daisy-like, white, pink or purple appear. Grow in a pot of multipurpose compost where the plant will cascade over the edges.

FUCHSIA MAGELLANICA Var MOLINIAE

An upright, deciduous shrub,  that has lance-shaped, green leaves. From this arching stems of pendant, pale pink flowers appear from summer to early autumn. It will grow up to 2m tall in a large pot of soil-based compost.

HAKONECHLOA MACRA (Golden Hakonochlea) ‘Aureola’

A deciduous slowly growing grass that has green-striped yellow leaves in purple stems. In early autumn right through to winter, reddish-brown flowering spikes appear. Prefers to be grown in containers of multipurpose compost, where it will grow up to 40cm in height.

LAVANDULA PEDUNCULATA (French Lavender)

This evergreen shrub has aromatic, grey-green foliage, where small, scented violet flowers with purple-pink tops appear in late spring to summer. Best planted in a pot of gritty soil-based compost, where it will grow up to 80cm in height.

NARCISSUS (Narcissus) ‘Ice Follies’

This decorative perennial bulb has sword-shaped green leaves, where in mid-spring, single, cream coloured white flowers with pale yellow cups appear. This 40cm tall bulb should be planted in autumn in pots of multipurpose compost.

OSTEOSPERMUM (Cape Daisy) ‘Buttermilk’

This evergreen perennial has slim, mid-green leaves, from which, daisy-like, pale yellow blooms with blue centres appear in summer. This 60cm tall perennial prefers to be grown in a container full of multipurpose compost.

PELARGONIUM (Scented Leaves Pelargonium) ‘Lady Plymouth’

A tender perennial that is often grown as an annual, where lobed silver margined green leaves are produced on mass. The leaves are scented where lavender pink summer flowers are produced. Grow in pots of multipurpose compost, where it will grow up to 40cm in height.

PEROVSKIA ‘Blue Spire’

A deciduous subshrub that produces upright white stems of small, aromatic grey-green leaves. In late summer spikes of blue-purple flowers appear. This 1.2m tall plant grows well in soil-based compost.

PHORMIUM (New Zealand Flax) ‘Bronze Baby’

This upright, evergreen perennial has mounds of arching sword-shaped purple-bronze leaves, where it will make a  bold statement in a large container filled with soil-based compost. Under these growing condition, it will reach a height of 60cm.

PINUS MUGO (Dwarf Mountain Pine) ‘Mops’

A compact evergreen conifer producing masses of needle-like, dark green leaves, where it combines well with spring flowering bulbs and/or other small shrubs. Mops will grow up to 1m in height when planted in a large container of soil-based compost.

ROSA (Rose)

Roses make a good specimen in a roof container garden, where the colourful blooms provide a point of interest from summer to autumn,

Rosa ‘Flower Carpet Series’ is a spreading ground cover rose. It has disease resistant, glossy leaves, cupped with semi-double, pink, red, yellow or peach blooms are produced profusely. Plant this 60cm tall plant in a large container of enriched multipurpose compost.

Rosa ‘Iceberg’ is a floribunda bush rose that has glossy, green leaves. From which cupped, fully double, white flowers appear. Grow it in a large pot full of enriched multipurpose compost, where it will grow up to 75cm tall.

Rosa ’Kent’ is another spreading ground-cover rose. It also has disease resistant, glossy mid-green leaves. Flat, semi-double white flowers appear from summer to autumn. Grow in a large container full of enriched multipurpose compost, where it will be allowed to trail over the edge. It will grow up to 90cm in height.

Rosa ‘Warm Wishes’ is a bushy hybrid rose that has some disease resistance. The shrub has mid-green leaves where fully double, scented, coral pink flowers appear. Grow in a large container of enriched multipurpose compost, where it will grow up to 1m in height.

ROSMARINUS OFFICINALIS (Rosemary)

An evergreen shrub whose leaves are used as a herb. It has aromatic, need-like, dark green leaves, where small, blue flowers appear in spring. This 1.5m tall shrub prefers growing in a large container full of gritty soil-based compost.

SALVIA GREGGII (Autumn Sage) ‘Navajo Series’

A woody perennial that has oval, mid-green leaves, where clusters of small, red, purple, pink or white flowers appear from late summer to autumn. It will grow up to 50cm in height in containers full of multipurpose compost.

SAMBUCUS RACEMOSA (Red-berried Elder) ‘Plumosa Aurea’

A 3m tall upright, deciduous shrub that has bronze leaflets, where the leaves change to golden yellow in early summer. In spring, yellow flowers appear that are followed by scarlet star-shaped fruits. Grow this elder in a large container in some shade.

SANTOLINA CHAMAECYPARISSUS (Cotton Lavender)

This is an evergreen mound-forming perennial that has finely cut, aromatic leaves, where in summer yellow, dome-shaped flowers appear on mass. This 75cm tall perennial prefers to be grown in a multipurpose compost.  It has an untidy growing habit and so to keep it tidy, trim after flowering.

SEDUM (Stonecrop) ‘Herbstfreude’

This clump-forming perennial has oval, fleshy, grey-green leaves, where it bears small, star-shaped red flower heads that appear in late summer. Sedums are best grown in a  multipurpose compost where it will grow up to 60cm in height.

SEDUM RUPESTRE (Reflexed Stonecrop)

A low growing perennial that forms mats of trailing stems bearing narrow, fleshy, green leaves. In summer, tiny star-shaped yellow flowers appear. This 20cm tall plant will trail indefinitely, and so would appreciate being grown as an edging plant in a shallow container full of soil-based compost.

SEMPERVIVUM ARACHNOIDEUM (Cobweb Houseleek)

This small perennial, only growing up to 12cm in height, has small rosettes of fleshy, green leaves. This evergreen perennial is covered with fine, white webbing and reddish-pink blooms in summer. Can be grown in small containers full of multipurpose compost.

TANACETUM COCCINEUM (Pyrethrum)

A 65cm tall perennial that has feathery, dark green leaves, where daisy-like pink or red flowers with yellow centres appear in early summer. Plant in groups in large pots of multipurpose compost. Deadhead regularly to encourage new bloom formation. It is not a long-lived perennial and so will need replacing in the near future.

CONCLUSIONS

In this article, plants that can be grown in containers in rooftop gardens have been discussed. The harsh environment does not stop plants of various kinds, forms, colours and growing habits from being used.

There are many plants of interest that can be implemented into a rooftop container garden, and no matter where you are in the world, there is a rooftop container plant for you.

If you have any comments you wish to be made, or a question that you need to ask, please do so in the comment box below.

Happy rooftop gardening.