Why is My Nemesia Dying? 6 Common Causes and How to Save Your Plant

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There are more than 50 species of Nemesia, and most of them are native to South Africa. However, only a few are popular garden plants, which are called cultivars. The two most popular species are N. strumosa and N. caerulea.

N. strumosa is a true annual plant that grows up to a foot tall and has blue or white flowers that are an inch across. N. The caerulea plant grows up to two feet tall and has flowers that are a half-inch across in purple, pink, blue, and white. Even more common as garden plants are the hybrid forms derived by crossing various Nemesia species.

Nemesia plants have lance-shaped leaves that grow in pairs along the stems. The flowers look like snapdragons and have two lips and a tube-like shape. As long as the weather stays mild, the plant can have so many flowers from spring to fall that they almost completely hide the leaves. Usually planted as a garden-ready nursery plant in spring, its also easy to grow from seed. People who live in places with cold winters can plant seeds directly in the garden for summer flowers or start them indoors to get flowers earlier. Gardeners in warm-winter climates often seed directly into the garden in fall for winter bloom.

With their delicate, colorful blooms, nemesia plants add charm and visual interest to gardens, containers, and hanging baskets. But these plants can sometimes take an unfortunate turn, leaving owners scratching their heads wondering why their once vibrant nemesia is now dying.

Luckily, nemesia issues can often be corrected with a few adjustments to care Read on to learn the most common reasons for a declining nemesia plant along with tips to get your flowers thriving once again.

Overview of Nemesia

Before diving into troubleshooting let’s overview some key facts about nemesia that impact its care

  • Native to South Africa, nemesia thrives in cool climates.

  • Most varieties grow 6-12 inches tall and spread 1-2 feet wide Trailing types work well in hanging pots.

  • Flowers resemble small snapdragons in white, pink, purple, yellow, orange or bicolor. Very prolific bloomers.

  • Requires full sun and moderately moist, well-draining soil.

  • Usually grown as annuals in zones 3-9, but may perennialize in zone 9-10.

  • Can rebound after summer heat by cutting back spent growth.

Top 6 Reasons a Nemesia Plant is Dying

If your once vibrant nemesia starts looking lackluster with wilting, spotty leaves and struggling blooms, review these common causes:

1. Improper Watering

Too much or too little water can stress plants. Nemesia needs consistently moist soil but hates soggy roots. Overwatering leads to fungal issues while underwatering causes wilting.

Solution: Water thoroughly only when the top inch of soil is dry. Improve drainage in heavy soils.

2. Extreme Temperatures

Temperature extremes damage nemesia. Hot sun over 75°F burns foliage and flowers causing dieback. Frost below 30°F kills the plant.

Solution: Move pots to shade during hot afternoons. Bring containers indoors if frost threatens.

3. Lack of Sunlight

Insufficient sunlight leads to weak, leggy growth with few blooms. Nemesia thrives in full sun – at least 6 hours of direct light daily.

Solution: Find a new spot with maximum sunlight, especially important in spring and fall when light levels are lower.

4. Nutrient Deficiencies

Yellowing leaves often indicate a nitrogen deficiency. Without proper nutrition, plants become stressed and decline.

Solution: Fertilize every 2-3 weeks with a balanced soluble plant food during the growing season.

5. Pests

Spider mites, thrips, slugs and other pests damage plants. Watch for chewed leaves, sticky residue or visible insects.

Solution: Remove pests by hand or use organic insecticidal soap. Improve conditions to deter future attacks.

6. Disease

Several fungal issues plague nemesia like botrytis, powdery mildew, and root rot. These quickly spread to infect the whole plant.

Solution: Improve air circulation. Avoid wetting foliage. Remove and destroy diseased plants to prevent spreading spores.

How to Revive a Dying Nemesia Plant

If your nemesia starts declining, take prompt action to nurse it back to health:

  • Assess soil moisture and water thoroughly if dry. Drowning roots is worse than underwatering, so allow soil to partially dry before next watering.

  • Move pot to a shady spot out of intense afternoon sun, especially if over 85°F.

  • Apply a general purpose fertilizer according to label directions. Repeat every 2-3 weeks.

  • Inspect closely for pests and treat accordingly. Isolate affected plants to avoid spread.

  • Prune off any dead, diseased or damaged growth. Disinfect pruners between cuts.

  • Transplant into fresh soil or repot if the original soil is dense, depleted or waterlogged.

  • Cut back severely distressed plants by 1/3 to encourage fresh regrowth.

How to Prevent Future Nemesia Problems

While nemesia issues can often be remedied, prevention is the best approach. Here are proactive care tips:

  • Select disease-resistant varieties better suited for your growing zone.

  • Plant in porous potting mix and containers with drainage holes.

  • Water at the soil level rather than overhead to deter fungal disease.

  • Space plants appropriately to allow air circulation.

  • Apply mulch to insulate roots and maintain even soil moisture and temperature.

  • Stake or cage tall varieties to prevent damage from wind and rain.

  • Monitor closely and treat pests before they become severe.

  • Avoid overhead watering and prune off infected parts immediately to control disease.

Enjoy Nemesia’s Delicate Beauty

With the right growing conditions and attentive care, it’s possible to avoid many common nemesia plant problems. A bit of TLC can nurse struggling plants back to their former vigor. Pay attention to your plant’s needs and make adjustments as issues arise. Then you can sit back and revel in the delicate beauty of nemesia blooms all season long.

Water

While its important to keep the soil moist for these flowers, be wary of over-watering. Too much water will lead to stem rot.

Potting and Repotting Nemesia

Nemesias make good specimens for outdoor containers. Use a large, well-draining container. Normal peat-based potting mix is usually enough, but some gardeners like to add extra sand, perlite, or vermiculite to make it drain better. You can also use regular garden soil in pots, but make sure there is a lot of compost mixed in.

Make sure to monitor potting mixture moisture and water whenever the top inch becomes dry to the touch.

How to propagate a Nemesia plant. Flowering of Nemesia. Nemesia Care | Alexa’s Garden

FAQ

How do you revive Nemesia?

Don’t immediately give up on nemesia plants that die back during the heat of summer. These plants do hate extreme heat, but if you radically cut them back and keep them well-watered, they often respond by rebounding and producing another flush of flowers in the fall.

How do you save Nemesia?

If you want to keep your perennial nemesias to flower the following year, move them to a frost-free spot to overwinter. More on growing nemsias: Nemesia, diascia and pelargonium hanging basket.

How often should I water Nemesia?

Keep the soil consistently moist to help the plant form a robust root system. This flowering beauty likes damp conditions, but too much water can cause root rot. Water Nemesia when the top few inches of the soil are dry.

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