If you see yellowing leaves on your nasturtiums, the first thing to check is the watering levels. If this isn’t the problem, there’s a likely chance that the plant is infested with a pest. You should also check for local herbicide use, as this can damage and discolor the leaves.
These problems are rare. Overall, nasturtiums are a fantastic choice for any skill level. These cheerful, bright flowers are easy to care for, and I love having them in my garden. I often recommend them to new gardeners, or as a great flower for young children first attempting to bring flowers to bloom.
Of course, troubleshooting problems is part of the learning process. So if you see signs of illness in your nasturtiums, such as yellowing leaves, don’t fear.
I’m here to answer the question “why are my nasturtium leaves turning yellow?” and provide advice on what could be going wrong so that you can get these flowers back to their former glory as quickly as possible.
Benefits of Nasturtiums
Nasturtiums are a fun option to grow because they have colorful blooms and are completely edible. Both the flowers and seed pods have a mustard-like taste and make an excellent garnish. They can also be pickled and eaten like capers.
I have a bunch of these fun flowers in my garden where they can attract bees with their lovely fragrance. However, if you don’t have garden space, they thrive in window boxes or hanging baskets too, becoming a beautiful trailing flower.
One of the reasons that nasturtiums are an easy option is that they aren’t hugely fussy about their soil. So don’t worry about growing them in poorer quality soils.
In fact, you are better off not using fertile soil, as this will only encourage the foliage to grow larger and you won’t see those beautiful flowers blooming.
These plants also do not need as much sunlight as other bright flowers and can grow in partial shade. My nasturtium baskets actually grow better in the shaded side of my garden. Between 3-6 hours is enough sunlight, which should be easily achievable from the garden or window box.
The two biggest factors to watch out for when it comes to nasturtium care are the level of watering and pest control. If you start to see the nasturtium turning yellow, check these first.
Nasturtiums need frequent watering, about one inch per week. Although they can be somewhat drought tolerant, if kept from moist soil you may start to quickly see a change in their appearance. They will stop blooming, look shabby, and the leaves will turn yellow.
On the other side, ensure your nasturtiums are not overwatered and have adequate drainage. If left sitting in soggy soil, mold and mildew may affect the plant and cause the leaves to yellow.
The soil should be evenly moist without ever seeming waterlogged. If you think the plant may be over or underwatered, rectifying this issue should soon get those leaves back to green. If any leaves are fully discolored or dead, cut them off to restore health to the flowers.
If watering isn't the problem, it’s time to look for signs of pests.
Aphids love nasturtiums, especially yellow nasturtiums. Some gardeners use nasturtiums as pest control, sacrificing them to save other crops in the garden.
If your nasturtium becomes infested, it will show the stress of these feeding aphids through yellowing or browning leaves. You might also notice mold or mildew.
So, if aphids are eating your nasturtiums, and you had no intention of sacrificing them for other crops, it’s time to tackle those troublesome little bugs.
Spray the plant down with a horticultural oil designed for aphids, or insecticidal soap. Sometimes, even just a strong jet of water may be enough to knock those pests from your plant’s leaves.
Avoiding nitrogen-rich soils or fertilizers is another great way to avoid aphid infestation. These fertilizers aren't necessary, and only make the plant more appealing to nutrient-sapping pests.
Another sap-sucker, the whitefly, may also be the pest responsible for turning the leaves of your nasturtiums yellow. Just as with aphids, the whitefly sucks the nutrients from the plant causing an unhealthy appearance.
Whiteflies are small yellow pests with white wings and a waxy appearance. They feed on the underside of the leaves. If you spot them, it’s also a good idea to spray the plants down with water to dislodge them and their eggs.
For heavier infestations, horticultural oil or insecticidal soap can help rid the pests. Creating a varied garden that attracts natural predators, such as ladybugs, is also a great idea.
Nasturtium Leaves Turning Yellow – Other Possibilities
If there are no signs of improper watering or pests, the culprit may be herbicides. An accidental hit of spray from a herbicide can cause yellow leaves in nasturtiums.
If you have been using any herbicides, or believe you may be downwind from a location that uses them, this may be a cause to consider.
Minor exposures should be easy enough for the flower to bounce back from. Unfortunately, a heavy dose may cause too much damage for a recovery. Communicate with your neighbors if you believe this to be an ongoing issue.
Frequently Asked Questions
Here are some of the most common other questions related to nasturtiums, asked and answered:
Q: How do I know if I’m overwatering my nasturtiums?
A: General signs of overwatering include soil that is soggy to the touch, yellow or spotted leaves, squishy stems, and increased pest attraction.
Q: When should I plant nasturtiums?
A: Nasturtiums should be planted shortly after the last spring frost occurs.
Q: Can I pick off yellow nasturtium leaves?
A: Yes, it is a good idea to remove leaves that have turned completely yellow to encourage healthy growth.
Q: Are nasturtiums good plants for pollinators?
A: Absolutely! The bright colors and lovely fragrances are great for attracting bees and hummingbirds to the garden.
Q: How do you harvest nasturtiums?
A: Simply snip off the edible parts of the nasturtium (the young, tender leaves, the buds, and the flowers) with sharp scissors when you would like to eat them.
Nasturtium Leaves Turning Yellow – Conclusion
The most common reasons for yellowing leaves in nasturtiums are all listed above, so I hope you have found the problem (and solution!).
Most of them are reversible, and the plant will begin to recover once the issue is rectified. Then you can go back to enjoying the sight, smell, and taste of your lovely nasturtiums!