Ornamental · Scrophulariaceae
Nemesia
Nemesia strumosa
Give it cool weather, steady moisture, and full sun, and nemesia floods a spring bed with color.
Full sun
Every 2–4 days
39–75°F · 4–24°C
USDA 2–11
Overview
Nemesia is a low, quick-growing flower from southern Africa, its bright, two-lipped blooms the reason it goes by Cape jewels. A figwort-family plant that keeps to just 6 to 12 inches tall, it slots naturally into the front of a border, a sunlit window box, or a container set by a doorway to greet the morning. The flowers arrive in nearly every color and keep the scene going for as long as the weather stays mild.
It lives as a cool-season annual, and that rhythm decides where and when it earns its keep in a garden. Planted around the last frost, it carries a bed from spring into early summer, then steps back once the heat settles in. In mild-summer regions it lingers as a season-long fixture, while in hot ones it reads best as a spring or fall accent.
Once it has found its spot, nemesia fits easily into a garden routine. Give it full sun, rich soil, and steady moisture, pinch it young so it rounds out into a tidy mound, keep after the spent flowers, and it holds a long, generous run of color that pulls a bed or a pot together.
Care
The short version: a full-sun, cool-weather spot, evenly moist yet well-drained soil rich in organic matter, a balanced feed across the growing season, and a pinch when young to shape a full, tidy mound.
Light
Nemesia holds its best color in full sun, though a touch of afternoon shade suits it where summers run hot. Too much shade thins the flowers and lets the plant stretch out of its neat shape, which undercuts the tidy look it is prized for.
Water
Keep the soil evenly moist but never soggy, watering every 2 to 4 days and more in heat. Water at the base and leave the foliage dry, since wet leaves invite the powdery mildew that dulls a planting.
Soil
Set it in humusy, well-drained soil that runs loamy or sandy and rich in organic matter. It is relaxed about pH across 6.0 to 8.0, but a soggy root zone quickly spoils the display.
Temperature
This is a cool-weather plant, at ease between 39°F and 75°F (4°C to 24°C). It takes light cold in stride, though it loses its shape once the days turn hot and the nights stay warm.
Humidity
Ordinary outdoor humidity suits it, so there is no figure to chase. What shapes the look far more is good air movement, since still, damp air around a crowded planting is what lets mildew take the shine off.
Feeding
Offer a balanced fertilizer monthly through the growing season to keep the color coming. Yellowing leaves or a purple cast are the plant's signal that a feed is due.
Pruning
Pinch the growing tips once or twice while young so the plant rounds into a full mound rather than stretching, and deadhead spent flowers to keep the display fresh. When bloom slows or heat sets in, cut back by a third to a half to bring on a new flush.
Size & spacing
Nemesia keeps a compact 6 to 12 inches (15 to 30 cm) tall and about as wide, which makes it easy to place along an edge or in a grouped pot. Set each plant 6 to 12 inches (15 to 30 cm) apart so air moves through and the planting stays clean.
When to plant
Nemesia keeps to cool weather and steps aside once summer turns hot, so a little planning sets up the display. Start the seed indoors in late winter, set the plants out around your last frost, and let them carry the garden from spring into early summer before the heat calls time.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Start seeds indoors 8 to 10 weeks before the last frost date.
- Plant: Set out seedlings or starter plants around the last frost date as a cool-season annual.
- Harvest: Blooms spring into early summer; in hot climates best in spring or fall, with summer heat causing dieback.
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Most nemesia trouble traces to one of two things: heat, or watering that has drifted out of balance. Keep an eye on the whole plant through summer and on the foliage the rest of the year. Match what you see below and step in while it still shapes the outcome.
The planting slumps from rotted roots
A bed or pot that holds water and never drains sets up root rot, and the roots turn brown and soft beneath a collapsing display. Plants this far gone are past rescue, so lift the sound ones and resettle them in soil enriched with compost. From then on, a lighter watering rhythm that lets the ground dry between drinks keeps the arrangement upright and healthy.
Fix:
- Improve drainage with organic matter
- Avoid overwatering
- Replant healthy plants in well-drained soil
The display fades as summer turns hot
Nemesia is a cool-season plant, so the arrival of hot, humid days and warm nights quietly dims the show it was putting on. Shift the container or bed into afternoon shade, keep the soil evenly moist, and cut the plant back by a third to a half to invite a second act. More often than not the display returns once the season eases into cooler weather.
Fix:
- Provide afternoon part shade
- Cut plants back by one-third to one-half to encourage new growth
- Keep soil evenly moist during heat
A pale film dulling the foliage
That chalky pale film is powdery mildew, which creeps in where foliage stays damp and the air around a crowded planting hangs still. Water at the soil line to keep the leaves dry, and set the plants with enough breathing room for air to drift between them. A pass of neem oil restores a stubbornly filmed planting to its clean look.
Fix:
- Water at the soil line and keep foliage dry
- Improve spacing and air circulation
- Apply neem oil if needed
New growth looking twisted or speckled
Curled tips, a sticky honeydew sheen, or fine silvery speckling betray aphids or thrips working the tender new growth. A firm rinse of water resets a light case, and insecticidal soap or neem oil settles a heavier one before it spoils the look of the planting. A quick glance every few days keeps these pests from marring an otherwise polished display.
Fix:
- Spray with insecticidal soap
- Apply neem oil
- Rinse off light infestations with water
Toxicity
Good news for pet owners and parents: nemesia is non-toxic to people and animals alike. The ASPCA does not list it among toxic plants, so it can hold a spot in a bed or on a terrace your cat, dog, or rabbit reaches, with nothing to worry over.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Nemesia sits easily in a home with cats, since a curious nibble will not poison one. A large mouthful of any plant can still leave a cat with a passing upset stomach, and this is no different.
Dogs None
A dog can share a garden bed of nemesia with no cause for concern, because none of the plant is toxic to them. At most, a chewed stem brings a little drool or mild tummy trouble from the roughage.
Horses Safe
Nemesia carries no known toxins for horses and belongs without worry where they graze.
Rabbits Safe
Rabbits can browse nemesia in safety, as the plant holds nothing that would harm them.
Livestock Safe
Cattle, goats, and sheep are in no danger from nemesia set in or near their pasture.
Birds Safe
The plant poses no threat to birds, whether they take to the seed or the foliage.
People Safe
Nemesia earns its place for its flowers rather than the table, yet it is not poisonous, and a curious child who tastes a bloom comes to no harm.
Varieties
Nemesia arrives in many named strains, sorted mostly by height and color to suit the look you are after. A few turn up often and are worth knowing when you plan a planting.
Blue Gem
A compact strain of just 6 to 9 inches, dressed in clear, true-blue flowers.
Carnival
A fuller, bushier plant of 9 to 12 inches that arrives in a bright mix of colors.
Triumph
A dwarf strain offered as a mixed-color blend made for tight corners and neat edging.
How to propagate
Nemesia is simple to multiply for next season, whether you sow a packet of seed in late winter or root a few cuttings from a plant already earning its place.
SeedEasy
Start indoors 8 to 10 weeks before last frost, or sow outdoors in spring. · Germinates in roughly 1 to 2 weeks; flowering within a couple of months.
Seed is the usual route to a season of nemesia. Sow it indoors 8 to 10 weeks before your last frost or scatter it outdoors in spring, and because the seed favors darkness, cover it lightly and keep it moist. Seedlings appear in 1 to 2 weeks, and the flowers follow within a couple of months.
Stem cuttingsModerate
Take soft-stem cuttings in summer. · Roots form in about 4 to 6 weeks.
To carry forward a plant whose color you have grown fond of, cuttings do the job with a little patience. Take 4 inch soft-stem cuttings in summer, dip them in rooting hormone, and keep them moist while roots settle over the next 4 to 6 weeks.
Myths
Nemesia is a true perennial that comes back on its own every year.
It is a tender perennial from southern Africa, though scarcely any garden manages it as one. It rarely lasts through a hot summer or a cold winter, so most gardeners replant it fresh each season and enjoy it as a cool-season annual.
Nemesia loves summer heat like most bedding annuals.
It is made for cool weather and loses its poise through hot, humid days and warm nights. Summer heat often kills it back, unless a firm cutback and a spot of afternoon shade see it through the worst.