How to grow nemesia

What you need to know about nemesia  

Name: nemesia (Nemesia hybrid, Nemesia strumosa varieties often crossed with Nemesia versicolor).

Height: 20-40cm x 20-40cm depending on variety.

Plant type: annual or perennial, depending on variety.

Climate: tropics, sub-tropics, warm temperate, temperate in sheltered areas depending on variety.

Soil: quality, free-draining soil but adaptable.

Position: full sun to part shade. 

Flowering: late winter through to summer, autumn and spring, depending on variety.

Feeding: improve soil when planting, apply controlled-release fertiliser, liquid feed regularly.

Watering: water well during hot periods. Mulch well.

Appearance and characteristics

Nemesia is a fabulous choice for a long display of truly delightful flowers across the shoulder seasons when it can be difficult to find reliable colour. Hailing originally from southern areas of Africa, nemesia are in the Scrophulariaceae (figwort) family. A typical characteristic of this family is ‘bilaterally symmetrical’ flowers, meaning the left side is a mirror image of the right but the top is not the same as the bottom. Flowers in this family also typically have a tube or bell-like form.

Nemesias have quite intricate flowers about 2.5cm across. The flowers are somewhat orchid-like in appearance, they have a large lower lobe, this makes up almost half of the flower size, then multiple upper lobes. These are massed on short racemes, spikes, on the ends of the stems.

Nemesia have been cultivated and hybridised for many years and as a result there’s enormous variety in the range of colours, including white, cream, yellow, orange, pink, red, scarlet, blue and purple. Select varieties show multiple solid colours in each flower, for example the upper flower lobes may be vibrant red while the lower lobe is a delicate pink. Many flowers are also patterned with streaks of colour and all blooms have a coloured throat, generally with spots or stripes. In short, you’ll find a colour to suit any outdoor scene. Most flowers have a gentle perfume, too.𠊊s there has been so much cross breeding you’ll find some are purely seasonal annuals, lasting for 3-4 months while others are perennials, lasting a number of years.

The form of the nemesias is best described as a low-growing mound. Their foliage ranges in colour from dark to light green and the leaves themselves are soft, lanceolate, that’s long, thin and pointed, up to 8cm in length and are distinctly toothed along their edges.

Uses for nemesia

Perfect when you need cheerful, fast growing and long-lasting colour. Grow in pots and large hanging baskets, as feature plants in garden beds or as border plantings. They are well suited to cottage-style gardens.

How to plant and grow nemesia

Planting tips:

• Leave plants to soak in a bucket of diluted seaweed tonic as you prepare the soil for planting.
• Improve the soil before planting by blending in organic matter, quality compost or well-composted manure.
• Add a quality controlled-release fertiliser at planting time.
• If planting for a border, set out plants about 15-20cm apart.
• If planting in pots, use a premium quality potting mix and stand on pot feet, without a saucer underneath, to avoid the risk of waterlogging.

Caring for nemesia

Nemesia can be considered as falling into two main groups – annual and perennial. Both types benefit from regular liquid feeding during their main season of growth and flowering. Perennial forms should be fed well with a quality controlled-release fertiliser as flowering finishes.

Watering nemesia

• Water well following planting but don’t let them sit too wet.
• Requires only moderate watering under average conditions but water well during hot or dry periods. 
• Keep mulched with lucerne or pea straw to retain moisture and help stabilise soil temperature.

Pruning nemesia

• Throughout the flowering season, remove flowers as they finish to encourage new flowers from lower down the stem
• When the flowering season of the perennial form ends, prune all over to tidy up the shape and encourage bushiness. They can be cut back by around one-third of their overall size.
• With both forms, avoid pruning below the lowest foliage.

How to propagate nemesia

Most plants are unlikely to produce viable seeds, as nemesia are heavily hybridised, so your ability to re-grow from your own plant is limited.

Perennial forms can be struck from cuttings. Take cuttings about 10cm long from non-flowering wood, dip in hormone gel and make holes with a pencil in a propagating mix. Keep warm and well-watered.

Diseases and pests

• Watch for slugs and snails with young seedlings.
• Aphids may be an issue on new shoots. These can be easily treated with a pyrethrum-based spray.

Keep in mind...

• Wear gloves and a mask when handling mulch, compost and potting mix and also when pruning, along with long sleeves, as the leaves and sap of some plants can be a skin irritant and cause allergic reactions.
• If using products to deal with pests, diseases or weeds, always read the label, follow the instructions carefully and wear suitable protective equipment.
• Store garden chemicals and products out of reach of children and pets.

Looking for a bit of guidance in the garden?

Check out our series of location-specific articles to help you green up your thumb.

Photo credit: Adobe Stock