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

Description and botany

Nemesia, also called Némésie or Mirror of the Elves, is a herbaceous plant, groundcovering or even trailing depending on variety, of the family Scrophulariaceae, like snapdragon or foxglove. It grows on sandy, coastal soils and fallow land of South Africa.

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

Nemesia strumosa is at the origin of numerous horticultural varieties such as the hybrid nemesia 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 vivid, very varied colours such as ‘Pink Lemonade’, ‘Danish Flag’ (Drapeau danois), with red and white flowers, and ‘KLM’, with blue-and-white flowering.

Depending on variety, habit is bushy and erect or groundcovering to trailing. With rapid growth, these small shrubs form a compact clump whose height varies from 15 to 30 cm at most.

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

Nemesia is remarkable for its floribundity and exotic, sometimes whimsical flowering, which stands out against this dense, graceful vegetation. Nemesia has the particularity of flowering almost continuously, sometimes from late winter depending on climate, until autumn. Nemesia fruticans presents a perpetual flowering that sometimes pauses before resuming strongly.

From June to October, often without interruption, the dense foliage is hidden beneath a myriad of small symmetrical flowers 1 to 3 cm across. They arise in the axil of the leaves or are gathered in loose, rather short terminal clusters on the erect stems, creating an airy cloud of infinite delicacy.

Nemesia flowers are bilabiate; the upper lip is formed of four petals, the lower lip of two inflated and fused petals. The whole is centred on a golden-yellow or white throat. A precise pattern that gives the inflorescences the appearance of jewellery, reminiscent of the shape of certain orchids or of the violet, hence its nickname ‘Cape Jewel’.

Nemesia cheiranthus ‘Shooting Stars’ stands out for its flowers with a very exotic look evoking shooting stars with their frayed white crest.

Nemesia flowers come in an infinity of colours, single or bicoloured, pastel and velvety very luminous blues, whites, pinks, lilac-pink, purples, yellows or, conversely, rather picturesque reds and oranges, as in Nemesia strumosa ‘Mello Red & White’.

Flowering of some hybrids emits a deliciously sweet perfume of honey and coconut that attracts foraging insects throughout summer.

Nemesia is a relatively frost-sensitive plant; some species resist short frosts of around -7 or -8°C and should be planted outdoors only in regions with mild winters. Everywhere else, this plant is commonly cultivated as an annual.

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

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

Nemesia takes its name from Nemesis, the 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 cold-sensitive perennial species reserved 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 valued for their abundant flowering and 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 in planters.

Our favourites

Nemesia strumosa Sunsatia Plus Berry Delight

A new nemesia, well ramified and compact, which produces an abundant, long flowering display in pink and cherry-red. 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 plant with a neat habit, 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 new-generation nemesia, highly floriferous from early spring to first frosts. Neat and continually in flower, perfect near house, on 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, fragrant flowering is outstanding 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 an almost continuous, fragrant flowering from May to October on a very ramified plant. A rounded plant with a gourmand 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 add colour to flowerbeds, 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 very frost‑tender and hardly tolerates temperatures below -3 to -8 °C. For this reason, it is most often grown as an annual in our climates. It can be planted in ground and remain perennial in regions with very mild climate completely free of frost, but elsewhere grow it in pots.

Nemesia is quite tolerant of wind and rain as well as summer drought, which makes it ideal for containers and window boxes.

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

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

Versatile, it blooms on terraces as well as in gardens. In summer it fits into all perennial borders, lines paths and, with its sometimes trailing habit, beautifully adorns hanging baskets, window boxes and all kinds of containers. 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 on receipt and kept under cover for a few weeks before planting outside once frost risk has passed.

How to plant Nemesia

In the ground

Allow 4 to 5 Nemesia per m2 and maintain a planting distance of 25 cm between each plant.

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

Growing Nemesia in pots

Nemesia is ideal for growing in window boxes, containers or pots! Compost must be very free‑draining to avoid waterlogging around the roots.

• In a wide, deep pot, spread a good draining layer of gravel or clay pebbles
• Plant into a slightly sandy mix of geranium compost
• Water without saturating

Charming pots of Nemesia ‘Pink Lemonade’

When and how to sow Nemesia

Sowing Nemesia seeds is done in March under cover to obtain earlier flowering or 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 compost
• Cover seeds with a fine layer of compost and keep sowings in light and warmth at 20–25 °C
• Keep substrate moist but not waterlogged until germination, which takes 7–14 days
• Transplant young plants when they have 3 leaves into larger pots
• Plant out in open ground once soil begins to warm in May or move pots outdoors once risk of frost has passed

In open ground

• In May, scatter Nemesia seeds or sow in shallow furrows in well‑worked, loosened soil
• Cover with a fine layer of compost
• Water regularly until germination
• Thin out to leave one plant every 25 cm

Maintenance, pruning and care

In pot or in ground, Nemesia must be watered regularly but always without excess as it is very sensitive to excess moisture which causes root rot.

Water more frequently during dry periods but never waterlog substrate.

Before winter, mulch base of perennial nemesias planted in ground.

From late May, to support flowering of plants in pots, apply ‘special flowering plants’ fertiliser.

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

Pruning of Nemesia

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

Aside from pruning, a light cut back between two flowerings is recommended to encourage formation of new flowers.

It tolerates a severe refresh in summer. In July and August, you can cut back the Nemesia to 10-15 cm from base, which will encourage the plant to renew its flowering.

Diseases and potential pests

Nemesia is sometimes prone to powdery mildew. Follow our tips to combat powdery mildew.

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

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

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

Propagation

Nemesia propagates easily by herbaceous cuttings in summer.

How to take Nemesia cuttings

• Take stems about 8-10 cm long from the tips
• Remove lower leaves and any 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 warm, bright conditions and keep the compost moist
• When 2 or 3 new leaves have formed, plant out in the garden or into a planter

Companion plants for nemesias

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

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

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

In the foreground of a bed of radiant annuals, it pairs easily with Ficoides, Cosmos, Nigella damascena, flax and California poppies.

Varieties with soft hues cannot compete with bright, flashy colours but create a beautiful effect alongside silvery, velvety-foliaged plants such as stachys.

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

Another pairing idea: 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 the edge of a path or in a rockery, it will bring a sophisticated note alongside dwarf roses, gypsophilas, Dorotheanthe difformis.

It will be especially effective for masking the base of a climbing with exotic looks such as a trumpet vine, or simply a clematis.