<em>Nemesia</em>: planting, cultivation and care

Description and botany

Nemesia, Némésie or Mirror of Elves is a herbaceous plant, mat-forming or trailing depending on variety, of family Scrophulariaceae, like snapdragon or foxglove. It grows on sandy soils, coastal sites and fallow land of South Africa.

Genus comprises about 50 perennial, annual or undershrub species. Most common in gardens are Nemesia fruticans (syn. Nemesia caerulea), a frost-sensitive perennial suited to mild climates, and Nemesia strumosa, a frost-tender species: both are most often grown as annuals or biennials in our regions because of low frost resistance.

Nemesia strumosa is source of many horticultural varieties such as hybrid series named ‘Sunpeddle’ or ‘Sunsatia Plus’ with bushy vegetation, more floriferous and with a more ramified habit. There are also quite spectacular cultivars with compact forms and bright, varied colours like ‘Pink Lemonade’, ‘Danish Flag’ with red and white flowers, and ‘KLM’ with blue-and-white flowering.

Depending on variety, habit is bushy and upright or mat-forming to trailing. With rapid growth, these small shrubs form a compact tuft reaching 15 to 30 cm maximum.

Stems, sometimes velvety and thin, well branched from base, bear bright green, dark green or grey-green foliage, semi-evergreen or deciduous depending on climate. Foliage composed of small opposite, elongated leaves 2–7 cm long. Entire, lanceolate, leaves are often very dentate and slightly pubescent.

Nemesia is notable for its floriferousness and exotic, sometimes whimsical flowering which stands out against dense, graceful foliage. Nemesia has the peculiarity of flowering almost continuously, sometimes from late winter depending on climate, through to autumn. Nemesia fruticans shows a perpetual flowering that may pause then resume more vigorously.

From June to October often without interruption, dense foliage is overwhelmed by a myriad of small symmetrical flowers 1–3 cm wide. Flowers arise in leaf axils or are gathered in loose, rather short terminal clusters on erect stems, creating an airy cloud of infinite delicacy.

Nemesia flowers are bilabiate; upper lip formed of four petals, lower lip of two swollen, fused petals. Whole centred on a golden-yellow or white throat. Precise pattern gives inflorescences a jewel-like appearance, reminiscent of some orchids or violets, hence common name ‘Cape Jewel’.

Nemesia cheiranthus ‘Shooting Stars’ stands out with very exotic-looking flowers evoking shooting stars with their fringed white crest.

Nemesia flowers come in endless single or bi-coloured shades, pastel and velvety luminous blues, whites, pinks, pink-lilac, violets, yellows or, conversely, rather striking reds and oranges, as in Nemesia strumosa ‘Mello Red & White’.

Flowering of some hybrids emits a deliciously sweet honey and coconut scent that attracts pollinating insects all summer.

Nemesia is a relatively frost-sensitive plant; some species tolerate brief frosts around -7 or -8°C and are suitable in-ground in regions with mild winters. Elsewhere, plant is commonly grown as an annual.

Nemesia prefers light, fertile, humus-bearing, very well-drained soil, even calcareous, in sun or possibly partial shade.

It is used in perennial beds, as path edging but proves spectacular for dressing hanging baskets and window boxes.

Nemesia takes its name from Nemesis, Greek goddess of righteous anger.

Main species and varieties

Most common in our gardens are Nemesia strumosa, which is frost-tender, and Nemesia fruticans, a frost-sensitive perennial to reserve for regions with mild winters. That is why in our gardens, nemesia is most often grown as an annual. Today there are interesting series of hybrid nemesias prized for their floribundity and their lasting display. They offer a palette of varied colours, often bicoloured, sometimes bold, even picturesque! All nemesias create a truly spectacular effect in the garden as well as on terraces in hanging baskets and planters.

Our favourites

Nemesia strumosa Sunsatia Plus Berry Delight

A new Nemesia, well-ramified and compact, producing abundant, long-lasting pink and cherry-red flowering. Magnificent in hanging baskets and planters.

• Flowering time June to November
• Height at maturity 25 cm

See the product sheet

Nemesia Honey White

An exclusive variety of the brand-new Sunpeddle series that forms a small, very bushy, neat-looking mound, in flower until first frosts. Exceptional in planters and flowering pots.

• Flowering time June to November
• Height at maturity 25 cm

See the product sheet

Nemesia Sunpeddle Painted Rose

A latest-generation Nemesia, very floriferous from early spring to first frosts. Neat and constantly in flower, ideal near the house, on the terrace or balcony.

• Flowering time June to November
• Height at maturity 30 cm

See the product sheet

Nemesia strumosa Sunsatia Plus Little Vanilla

Its generous scented flowering is astonishing in hanging baskets and planters. This well-ramified, compact plant is weather-resistant.

• Flowering time June to November
• Height at maturity 30 cm

See the product sheet

Nemesia Pink Lemonade

A fantastic cultivar, offering almost continuous, fragrant flowering from May to October on a very ramified plant. A rounded plant with a delicious coconut scent.

• Flowering time June to November
• Height at maturity 30 cm

See the product sheet

Nemesia strumosa Compacta Tapestry Seed Mix - Cape Jewels

A mix of soft, velvety tones to bring colour to beds, border edges, rockeries or planters.

• Flowering time July to November
• Height at maturity 25 cm

See the product sheet

Planting

Where to plant Nemesia

If Nemesia is very easy to grow, it is also quite tender and struggles with temperatures below -3 °C to -8 °C. That is why it is most often grown as an annual in our climates. It can be planted in ground and may be perennial in regions with a mild climate completely free of frost, but elsewhere reserve for growing in pots.

Nemesia is however fairly resistant to wind and rain as well as to summer drought, ideal for use in pots and window boxes.

It grows in full sun or light shade in warm regions.

Nemesia needs well-drained soil, preferably rich, light, even sandy.

Versatile, it flowers terraces as well as gardens. In summer it fits into all perennial beds, along borders and pathways and, with its sometimes trailing habit, beautifully adorns hanging baskets, balcony planters and all types of large planters. Its excellent groundcover qualities also make it indispensable in sunny rockeries.

When to plant Nemesia

In ground, plant Nemesia in spring, in April–May after last frosts. This plant does not tolerate sub-zero temperatures: our Nemesias in plug plants should be potted on upon receipt and kept under cover for a few weeks before planting outdoors once frost risk is definitively eliminated.

How to plant Nemesia

In ground

Allow 4 to 5 Nemesia plants per m2 and keep planting distance of 25 cm between plants.

• Dig hole 2 to 3 times volume of rootball
• Add well-draining layer of clay pebbles or gravel at bottom of hole
• Place rootball in centre and backfill hole
• Water regularly but without excess to ensure establishment

Growing Nemesia in pots

Nemesia is ideal to grow in window boxes, large planters or containers! Growing medium must be very free-draining to avoid stagnant moisture at roots.

• In a large deep pot, spread good draining layer of gravel or clay pebbles
• Plant in slightly sandy mix of geranium compost
• Water without waterlogging

Charming pots of Nemesia ‘Pink Lemonade’

When and how to sow Nemesia

Sow Nemesia seeds in March under cover for earlier flowering or direct in open ground in May. Warning! Nemesia seeds are so fine they are barely visible to the naked eye.

Under cover

• Sow Nemesia seeds in pots or trays filled with well‑moistened potting compost
• Cover seeds with a thin layer of compost and keep sowings in light and warm conditions at 20–25 °C
• Keep substrate moist but not waterlogged until germination, which takes 7–14 days
• Pot up young plants when they have 3 leaves into larger pots
• Plant out in open ground when soil begins to warm in May or move pots outdoors once risk of frost has passed

In open ground

• In May, sow Nemesia seeds thinly by hand or in shallow furrows in well‑worked, friable soil
• Cover with a thin layer of compost
• Water regularly until germination
• Thin out to leave one young plant every 25 cm

Maintenance, pruning and care

In pots as well as in open ground, Nemesia must be awatered regularly but never excessively because it is very sensitive to excess moisture which causes root rot.

Water more regularly during dry spells but never waterlog substrate.

Before winter, mulch base of perennial Nemesias planted in open ground.

From late May, to support flowering of specimens in pots, apply “special flowering plants” fertiliser.

Bring pots into greenhouse or conservatory to protect from frost during winter after pinching tips of stems by two-thirds.

Pruning of Nemesia

To prolong flowering, regularly remove faded flowers and spent stems.

Aside from pruning, a light cutback between two flowerings is recommended to stimulate formation of new flowers.

It does not mind being cut back severely in summer. In July and August, you can cut back Nemesia to 10-15 cm from base, which will encourage plant to renew flowering.

Potential diseases and pests

Nemesia is sometimes susceptible to powdery mildew. Follow our advice to combat powdery mildew.

Slugs can attack young shoots when they appear: discover how to deter them.

It can also fall prey to aphids: to eliminate them, spray with black soap.

In overly wet weather, thrips, tiny parasitic insects, can cause mottled foliage. As a preventive measure, in hot, dry weather, spray foliage regularly and spray garlic decoctions mixed with black soap.

Multiplication

Nemesia is easily propagated by herbaceous cuttings in summer.

How to take Nemesia cuttings

• Take stems about 8 cm to 10 cm long from the tips
• Remove lower leaves and remove flower buds
• Insert these cuttings up to the first leaf into pots filled with a light, free-draining mix of sand and potting compost
• Place in warmth and light, keeping compost moist
• When 2 or 3 new leaves have formed, plant out in garden or in a planter

Companion plants for nemesias

Nemesia’s flowering is precious for quickly bringing spots of light or adding an exotic touch to gardens and sunny terraces. The rich colour palette of its flowers allows monofloral displays in gentle or bolder combinations. It is indispensable in a pink garden or to create an exotic-inspired flower bed.

In a fresh, colourful planter, pair nemesias with diascias, geraniums, lobelias, verbenas or petunias.

An idea for a pairing: Diascia ‘Breezee Plus Pastel’, Verbena ‘Lilac Eye’, Nemesia ‘Sunpeddle Painted Rose’ and Lobelia ‘Hot Water Blue’

At front of a bed of radiant annuals, it pairs easily with Ficoids, Cosmos, Nigella damascena, flax and California poppies.

Varieties with soft tones cannot compete with bright, gaudy colours but create a beautiful effect alongside plants with silvery, velvety foliage such as stachys.

Among perennials flowering in summer, to give height to a bed, marry it with finer, ramified plants such as Verbena hastata, Verbena bonariensis and garden valerian or with bulbous plants such as ornamental alliums.

Another idea for a pairing: Rose ‘Bonica’, Centranthus ruber, Verbena hastata, Allium ‘Mount Everest’ (photo Patrick Standish) and Nemesia ‘Sunpeddle Blue Rose’ (photo PAP)

Its delicate flowers provide a flattering foreground for plants with more compact inflorescences such as sedums or achilleas.

At edge of a path or in a rock garden, it will bring a sophisticated note in company with dwarf roses, gypsophilas, Dorotheanthe difformis.

It will look wonderful to hide base of a climbing with exotic appearance such as a trumpet vine, or simply a clematis.