Nasturtiums are cheerful, easy-to-grow annual flowers that add a splash of color to gardens, large and small. But even the most robust nasturtium can succumb to problems from time to time. How can you tell if something is wrong with them, and what can you do to fix the problem?
Some of the most common signs that something is wrong with your nasturtium include yellowing leaves, stunted growth, damaged leaves, flowers not blooming, and black or brown spots on the leaves. These signs indicate the growth of pests, fungus, or issues with nutrients, sunlight, or water.
Nasturtiums are a great addition to your thriving garden. They’re so versatile—you can use the leaves in salads, the flowers in bouquets, and the plant is a great companion plant. But sometimes, even with your love and care, things go wrong.
Familiarizing yourself with the common signs and issues when growing nasturtiums, you can take steps to prevent serious damage to your plants.
Top 4 Signs Something Is Wrong with Your Nasturtium
Nasturtiums are typically robust plants that can thrive with a minimum of care. If left to grow undisturbed in the garden, they’ll often take over, covering the garden bed with their trailing veins. But sometimes, your nasturtium might sit there, looking a little yellow and sad, despite your best efforts.
Here are some top signs of something wrong with your nasturtium and what to do about it.
|Plant damage||Potential Causes||Natural Solution|
|Stunted growth||Too low temperature||Wait to plant until weather has warmed|
|Not enough sunlight||Plant in full sun, 6-8 hours per day|
|Too much water||Water 1-2 times weekly, 1 inch total|
|Poor soil drainage||Add organic matter, grow in containers|
|White spots on leaves||Powdery mildew||Ensure good airflow, remove infected leaves|
|Damaged leaves||Harmful insects||Spray off with water, insecticidal soaps|
|Yellow leaves||Nutrient overload||Avoid adding too many amendments to soil|
|Sunlight imbalance||Plant in full sun, 6-8 hours per day|
|Pests||Spray off with water, insecticidal soaps|
1. Stunted growth
Your nasturtiums may not be growing to their full potential and are smaller than usual. There are a few reasons why this could happen, most of which are easy to remedy.
- Temperature: Nasturtiums prefer temperatures of around 40 degrees Fahrenheit or higher. They can survive light frosts, but a heavy freeze will kill the plant.
- Not enough light: Nasturtiums need at least 6 -8 hours of full sunlight per day to grow their best. If they get less than 3 hours of light, they will become spindly and weak.
- Too much water: Overwatering can cause the roots to rot, eventually killing the plant because it can’t get nutrients or oxygen from the soil.
- Poor drainage: Nasturtiums need well-draining soil to thrive, as mentioned above. Some soils don’t drain properly, so preventative measures like growing in pots or raised beds can help.
2. White spots on leaves
If you notice white spots on your nasturtium plant, it is likely due to powdery mildew, a disease caused by the fungus Leveillula rutae. Overwatering or poor air circulation around the plant creates an ideal environment where fungi can thrive.
You’ll see yellowed spots on the leaves, followed by a dusty white coating. The nasturtiums can survive a case of powdery mildew, but they won’t grow as strong or produce as many flowers.
3. Damaged Leaves
Damaged leaves might have chew marks, bumps, or furled edges, which usually means your garden is suffering from pest pressure. Below are six common types of pests that target nasturtiums and their identification:
- Aphids: The adults are small, soft-bodied insects that can be black, brown, yellow, or green. They congregate on the undersides of leaves and stems, where they suck the sap out of the plant.
- Whiteflies: As their name suggests, these pests are small white flies that congregate on the undersides of leaves and feast on the sap.
- Spider mites: These tiny spider-like creatures spin webs on the undersides of leaves where they suck out the plant’s sap, leaving a curled and bumpy leaf behind.
- Leaf miners: The larvae of these insects burrow into the leaves and eat their way through, causing damage as they go.
- Thrips: These small, winged insects feed on the sap of plants by puncturing the leaves with their mouths and sucking out the contents.
- Squash bugs: These large brown or black bugs congregate on the undersides of leaves where they draw sap from the leaves.
4. Yellow leaves
Yellow leaves, like damaged leaves, can be a sign of pests in the garden, incorrect sunlight exposure, or a nutrient deficiency. It should be easy to figure out the culprit here.
- Nutrient overload: If the entire plant is yellow, your nasturtiums could be planted in too rich of soil and suffering from too much of a good thing. Nasturtiums prefer poor soil without too much nutrition to grow their best. There’s not much you can do to fix this one other than plant it elsewhere next time.
- Incorrect sunlight exposure: If only the leaves are yellowed with thin papery spots, they might be getting too much sunlight, and the leaves are sunburned. Move the plant to a shadier location and clip off the damaged leaves, or leave them (pun not intended) to grow out on their own. Confusingly, the plants might also be getting too little sunlight, and the yellowing is a sign that the plant can’t make enough sugar to support its growth.
- Pests: As mentioned above, pests like aphids and whiteflies can cause yellowing leaves as they feast on the sap. Check for them on the undersides of leaves and treat them accordingly.
Natural remedies for your nasturtium’s woes
Problems with nasturtiums are pretty infrequent, but if you do run into them, there are some natural and organic solutions that you can try.
Below, we’ll explore some of these treatments so that you can keep your nasturtiums looking their best:
Make sure your nasturtiums can grow at a temperature of 40 degrees Fahrenheit or higher. If the temperature is too hot or too cold, the nasturtiums will not grow or bloom properly.
Nasturtiums need at least 6-8 hours of full sunlight daily to thrive, though they can tolerate some shade. If they don’t get enough sunlight, their leaves will start to turn yellow, and their growth will be stunted. Choose a spot in your garden that receives plenty of sunlight throughout the day for the best growth.
Watering and drainage
Nasturtiums require moderate watering – at least 1-2 times a week. If the plant is sitting in waterlogged soil, it won’t be able to get the oxygen it needs to grow properly. You can improve drainage by loosening the soil around the plant with a trowel and adding pebbles or some organic matter, such as compost or peat moss.
For nasturtiums to thrive, it’s best to plant them in poor to average soil. Contrary to many garden plants that love rich soil, nasturtiums can get overwhelmed by soil that’s too fertile, stunting their growth.
Spray the affected leaves with neem oil, insecticidal soap, or organic pesticides. You should see results within a few days. Even better than a soap is to maximize the number of flowers in your garden to draw in more pollinators to help balance out any pests. It’ll take more time than an organic spray, but it’s better for your garden.
The fungus Leveillula rutae thrives in areas with poor airflow. Ensure that your plant has sufficient space for air movement around it. `
The table summarises the top issues your nasturtiums may face, the causes behind them, and their respective treatments:
Nasturtiums are beautiful and easy-to-care-for flowers that make a great addition to any garden. Observe your plants for any typical signs of inadequate or poor care so you can quickly diagnose any problems and take steps to correct them before they become too serious. You can get them back on track to being healthy and blooming beautifully with a little care.
- Can Nasturtiums Grow In Part Shade? (Here’s How To Succeed)
- Watering Your Home Garden Through The Season: A Complete Guide
- What Month Should You Start Planting Flowers?
My favorite garden soil supplies
When you know what condition your soil is in, it’s much easier to add anything that’s missing before your plants start to suffer.
- Find out your soil’s pH and macronutrient levels with an easy soil test kit.
- Even without a soil test, worm castings are a safe bet to add to any garden, and your plants will love them. Wiggle Worm Soil Builder is a high-quality amendment that I add to all my garden beds that need a boost.
- I often reference Farmer Jesse of The Living Soil Handbook on this blog. He’s a professional farmer with tons of information about soil science and how to build a healthy garden.
Find the rest of my “use on the daily” garden gear on my resources page.