Petunias are one of the easiest flowers to grow all year round in warm climates. But that doesn’t mean it’s resilient to pest problems. If you’re out of insecticidal soap sprays, can you use a homemade one?
As a whole, homemade bug sprays for Petunias or other plants have a high risk of causing plant injury. This is primarily due to the concentrated mixture of additives from the ingredients used. It’s better to hose the plant down with water before using diluted insecticidal soap as a last resort.
Below, I elaborate more on this, along with tips to prevent pests on your Petunias. But before that, a brief introduction …
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What Are the Common Pests that Infest Petunias?
Even though Petunias are relatively pest-free, certain bugs may appear and claim free real estate on the flowering plant. Here are a few of those culprits:
- Spider mites
If you’re growing your Petunias in an outdoor garden, don’t immediately take the big guns out and start spraying if you see these pests. Chances are you already have garden-friendly insects like ladybugs and ground beetles getting rid of them. You can read more about them and their benefits in this ‘Beneficial Bugs in the Garden’ article.
But if you have indoor Petunias, you’ll need to do all the dirty work. This is where you need to do a weekly pest & disease check on the plant. You can refer to this ‘Common Houseplant Pests & Disease’ article for signs to watch out for, like holes on leaves and sticky residue on the stems. I highly recommend following the instructions in the link above before even thinking about reaching for the insecticidal or homemade bug spray.
How to Make a Homemade Bug Spray for Petunias?
If you’re not a fan of using insecticidal soaps to eliminate nasty pests on your Petunias, here’s an easy homemade bug spray you can make:
- Obtain a gallon of filtered or distilled water. The purer it is, the better. Avoid tap water, especially if it’s hard water or contains a lot of minerals. Otherwise, it will make your mixture ineffective.
- Pick an unscented, diluted, pure liquid soap variety. This may include anti-bacterial and degreaser constituents. The fewer additives there are, the less damage sustained by the plant.
- Mix 1-2 teaspoons of soap into the gallon of water. Place this solution in a spray bottle and test it on one leaf first. Leave it for 1-2 days before checking on it again:
- If there is no change to the leaf, spray the mixture directly onto the pests consistently for a week.
- If there is visible damage on the leaf, the mixture’s concentration is too high or potent. Wash the plant off with water and redo the soapy solution again.
Important note: A homemade bug spray’s concentration is not carefully controlled or regulated like insecticidal soaps. So it may cause significant damage to the plant, especially sensitive ones. It also may be ineffective on some pests. If you want to know more about hits, I’ve discussed it in detail in this ‘Applying Soapy Water on Plants’ article.
Helpful Tips When Preventing Pest Infestations on Petunias
The best way to avoid a problem in the first place is not to run away from it but to set several preventive measures. Here are a few things you can do to keep your Petunias pest-free:
- Give the plant the best care possible. Most pest and disease problems stem from improper care or infected/infested plant upon purchase. While the latter is a bit tricky to handle, a healthy and well-cared Petunia is unlikely to suffer from any issues. Here are the top four things the plant needs to thrive:
- Full, direct sunlight.
- Well-draining, slightly acidic soil with pH 6-7.
- Watering every 7-10 days.
- Monthly feeding with diluted liquid fertilizer.
- Repot and change the potting media every year to discard hidden pest eggs and larvae. Some may continue lurking in the soil even after removing most of the annoying bugs. So this is the best way to ensure you eliminate them entirely.
- Plant Petunias far away from other nightshade plants like tomatoes and peppers. Because these plants tend to have the same pest & disease problems, planting them together increases the likelihood of it happening. Where possible, diversify your garden and avoid grouping plant members of the same family together.
Frequently Asked Questions About Pests on Petunias
Diluted insecticidal soaps and Neem sprays are safe to use on Petunias to eliminate pests. They need to be applied directly on the insects to take effect and require repeated use for up to 2 weeks. Homemade bug mixtures are also relatively safe so long as the concentration is not too potent.
Here’s what you need to do if your Petunia is overrun with aphids:
1. Quarantine the plant. You want to ensure the infestation is not spreading to your other plants. But make sure to check the rest, just in case.
2. Wrap the pot and plant’s base tightly with plastic. This ensures that no aphids will drop into the soil and lurk there when you do the next step.
3. Spray the plant intermittently with bursts of water. Ensure to do this outdoors or in your tub to minimize mess. Try to get every inch of your Petunia, aiming the spray under the leaves and between the stems.
4. Wipe the plant down with a damp cloth. This helps you remove any remaining aphids still hanging onto your Petunia.
5. Observe your plant for a week to see if any aphids appear again. If they do, it’s time to bring out the big guns and hit them with an insecticidal soap spray. Do this for about two weeks consistently or until after you don’t see any more aphids.
6. Repot the Petunia into a new pot with fresh potting media. This gives your plant a new start while getting rid of any lurking aphid eggs or larvae in the soil.
Whiteflies or mealybugs are the likely white bugs infesting your Petunias. While whiteflies can appear and flutter about when you shake the foliage, mealybugs are typically hidden between new leaves and stems. But they can both be easily removed – follow the instructions listed in this ‘Common Houseplant Pests & Disease’ article to get started.
Vinegar can be too potent to use on Petunias. There is also no evidence proving this homemade remedy effectively removes pests. If the concentration is not diluted, it may cause damage to the plant’s leaves. You can read more about it in this ‘Using Apple Cider Vinegar on Plants’ article.
Caterpillars, tobacco budworms, and cutworms may form holes in Petunias, feeding on the leaves and flowers. These pests are prolific when there are no beneficial bugs like ground beetles or wolf spiders to feed on them. You can remove them by hand-picking them off the plant or using a Bt (Bacillus thuringiensis) spray.
All in all, I wouldn’t recommend making or using a homemade bug spray to keep your Petunias pest-free. You may be adding more unnecessary stress to the plant. Let nature’s predatory bugs do the work for you, or hand-pick them off yourself and keep insecticidal soaps as a last resort. Happy planting!
- Carlin Munnerlyn. (2018). Insecticidal Soaps for Garden Pest Control. Home & Garden Information Center | Clemson University, South Carolina. https://hgic.clemson.edu/factsheet/insecticidal-soaps-for-garden-pest-control/
- Sep 27, F. | H. 1171 | R., & Print, 2007 |. (n.d.). Petunia. Home & Garden Information Center | Clemson University, South Carolina. Retrieved November 15, 2022, from https://hgic.clemson.edu/factsheet/petunia/
- Petunias – University of Florida, Institute of Food and Agricultural Sciences. (n.d.). Gardeningsolutions.ifas.ufl.edu. Retrieved November 15, 2022, from https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/petunia.html
- Managing Pests in Gardens: Floriculture: Petunia—UC IPM. (n.d.). Ipm.ucanr.edu. Retrieved November 15, 2022, from http://ipm.ucanr.edu/PMG/GARDEN/FLOWERS/petunia.html
- admin. (2018, March 6). Budworm – Petunia Calibrachoa, Geranium. Center for Agriculture, Food, and the Environment. https://ag.umass.edu/greenhouse-floriculture/photos/budworm-petunia-calibrachoa-geranium-0