If you’ve ever searched for a way to combat insects or mites on your Calathea, you’ve probably seen recommendations for a natural pesticide called neem oil – but you may have found almost as many people warning against it! Is neem oil actually safe for your Calathea?
If you dilute it to the right concentration and take the proper precautions, neem oil won’t harm your Calathea. However, it will make the plant more vulnerable to sun scorch in the short term; keep your Calathea well away from direct sun for a week or so after applying. To use neem oil as a pesticide, mix a small amount with water and a little dish soap, then mist it onto the plant’s foliage.
You can also add some neem to your Calathea’s water once per month to saturate the plant’s tissues with the active ingredient. This method is a bit slower, but the effects last longer, giving your Calathea some ready-made defenses against marauding pests. We’ll delve into the proper uses of neem oil in more depth below.
What is Neem Oil, Anyway?
Neem oil is pressed from the seeds and fruits of the neem tree, a member of the mahogany family native to India. It’s useful for both repelling and killing an enormous range of plant-eating bugs, including the following common Calathea pests:
- Spider mites
- Fungus gnats
The primary mechanism of action for neem oil is a chemical called azadirachtin. This compound doesn’t kill bugs directly; instead, it messes with their hormones to make them forget to eat and breed. They’ll starve to death without leaving behind any offspring – the perfect outcome for a plant grower trying to control an infestation.
Even better, since it has to be ingested to take effect, azadirachtin doesn’t bother beneficial insects like honey bees. If they aren’t munching on your plants, they aren’t affected!
When you’re looking to use neem oil to control pests, make sure you purchase it raw or cold-pressed. Other processing methods can significantly reduce the level of azadirachtin present.
Neem oil can range from yellow to dark brown, depending on how long the seeds were steeped during preparation. It has a strong smell that many people dislike – it’s been compared to garlic, onions, and sulfur.
Is Neem Oil Safe For Your Calathea?
Some Calathea growers will warn you never to use neem oil on these plants, sharing stories of plants that became discolored and wilted a few days after they were treated for pests. But while Calatheas can be somewhat fragile plants, under most circumstances, they’ll tolerate neem oil without an issue.
The problem is when you combine it with direct sunlight. Under normal circumstances, Calatheas can benefit from a couple of hours of morning or evening sunlight on their leaves, but they’re prone to sunburn if they get more than that – and neem oil enhances this sensitivity.
If you’re applying it as a topical spray, it’s best to keep your plant out of the sun for several days afterward. Make sure it receives only indirect illumination (light that’s reflected off or filtered through other surfaces) during this period. If you’re confused about the distinction, take a look at our article on lighting for Calatheas.
It’s also possible to damage your Calathea with an overly high concentration of neem oil. As with any oil, too much will clog the pores in the leaves, causing them to suffocate. One teaspoon of neem per liter of water should provide the beneficial effects you’re after without smothering your Calathea. If you’re worried your solution is too strong, try testing it on a single leaf first, then waiting a week or so to see whether its health suffers.
Is Neem Oil Safe for Your Kids and Pets?
We mentioned that neem oil only affects creatures that eat the treated plant. But what if you have little kids or furry companions that might decide to chew on your greenery?
We’re happy to report that as long as you stick to the concentration we recommended above, your pets and children should be able to munch on your Calathea’s lucky leaves with no consequences except a scolding.
That said, you should keep the bottle somewhere they can’t get to it. Swallowing a large amount of pure neem oil can sometimes cause lethargy, vomiting, diarrhea, and convulsions. If you find that your toddler has ingested concentrated neem extract, you should definitely call poison control.
How to Use Neem Oil on Your Calathea
To treat an infestation with neem oil, you’ll need to make an emulsion by mixing it into soapy water. The soap is there to help the oil dissolve; any mild dish detergent free of harsh additives like degreasing chemicals should work. Many houseplant owners like to use a soap that includes peppermint oil for a bit of extra insecticidal punch.
Add roughly ⅓ of a teaspoon of soap per liter of water and shake well. The water should be warm but not scalding hot. Now stir in the neem oil – as noted above, a ratio of one teaspoon per liter of water works best. Be careful to mix it well because if the neem doesn’t emulsify properly, it can form dense droplets that are more likely to block your Calathea’s pores.
Fill a spray bottle with this mixture and apply it to every inch of your Calathea, including the undersides of the foliage. Then wet a cloth or brush with the same solution and carefully wipe down the plant.
The best time of day for this procedure is in the evening, due to the reduced risk of sunburn. Remember that the mix only remains stable in water for around 8 hours, so don’t wait too long after shaking it up to use it. Regardless of when you spray down your plant, you should move it at least a few feet back from any nearby windows for a few days.
No matter what kind of pests you’re dealing with, you’ll probably need to repeat this treatment a few times to ensure that you’ve really wiped all of them out. For fast-breeding bugs like spider mites and scale, it’s best to alternate treatments every few days, switching between neem oil and other chemicals like rubbing alcohol or hydrogen peroxide. See our post on Calatheas and spider mites for more info.
You can use this topical treatment even when your plant is healthy, discouraging pests from setting up shop. Even a faint residue of neem helps to repel bugs, and you might catch early invaders before they’ve multiplied enough to attract your attention.
Neem Oil Soil Drench for Calatheas
You can also use neem oil as a systemic pesticide by including it in the water you give your Calathea. The roots will absorb the azadirachtin and it will spread throughout the plant’s entire body. This method is referred to as a soil drench.
This can be an effective preventative measure against pests or a way to combat a really stubborn infestation. It ensures that the bugs can’t avoid the deadly dose by simply hiding somewhere you can’t reach with your spray bottle. A soil drench is especially helpful for clearing fungus gnats, which hatch and grow to adulthood in the soil.
You can make the concentration a little stronger for a soil drench since you won’t be spraying it directly onto your Calathea’s delicate leaves. Try 1.5-2 teaspoons per liter of water, with a corresponding increase in the amount of soap. Then simply pour it into the soil just like an ordinary watering. Repeat this treatment once a month or so until the infestation is cleared, or for as long as you’re looking give the plant some extra armor against bugs.
Used with care, neem oil can be a powerful tool for keeping your Calathea pest-free. The guidance we’ve given above should help you knock out any troublesome bugs without harming your delicate tropical princess. Give it a try, and see for yourself why so many plant owners swear by neem.