September 2, 2026, 4:48 am | Read time: 3 minutes
For many hobby gardeners, aphids are among the most persistent problems of the entire gardening season. These small suckers quickly form dense colonies on fresh shoots and new growth, weakening the plants. Many then turn to a home remedy known to their grandparents: soft soap. But does this remedy really work as reliably as its reputation suggests? To find an answer, myHOMEBOOK asked Nabu.
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The Most Important Tip Comes Before the Soap
Before discussing soft soap, Silvia Teich, spokesperson for Nabu, has another piece of advice. “The most important tip for a garden with many aphids is to promote beneficial insects,” she says. This mainly refers to four types of insects that love to eat aphids.
- Lacewing larvae
- Ladybugs and their larvae
- Hoverflies
- Parasitic wasps
To attract these natural helpers to the garden, Nabu believes one thing is essential: a bit of wildness. “In a nature-friendly garden, they have a chance to develop as natural helpers and keep the aphid population in check,” Teich explains. Specifically, she recommends avoiding chemicals and artificial fertilizers and planting the garden with a variety of native perennials and shrubs.
Also interesting: Do ladybug larvae help against aphids?
The First Step When Infested
If the aphids are still present, soap isn’t the immediate solution. “We would recommend initially rinsing aphids off the affected plants with a stream of water,” says Teich. This simple method usually works well but needs to be repeated often, as new aphids quickly settle again.
Infusions and Decoctions for Severe Infestations
Only when the infestation is more severe does Nabu recommend using infusions or decoctions to spray the plants. An infusion with soapwort, for example, can remove sticky aphids because the plant contains a soap-like substance that dissolves the aphids’ adhesive substances. Tansy works differently; it contains substances that directly kill the aphids. According to Teich, both plants take effect shortly after spraying. Decoctions made from nettle, horsetail, or garlic are also suitable as natural remedies against aphids.
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And How Does Soft Soap Work Exactly?
This brings us to the original question. “Soft soap works similarly to soapwort,” Teich explains. “It removes the sticky aphids from the plant.” Instead of chemically poisoning the insects, the soap simply makes the surface too smooth and slippery for them to cling to.
Also interesting: Is milk a natural miracle weapon against aphids?
Sparingly and Targeted Instead of Widespread
A study on the parasitic wasp Aphidius colemani also shows the limits of this caution. Adult wasps die at a certain soap concentration, but their larvae inside the aphids remain unharmed. Therefore, researchers recommend using soap in the greenhouse one day before releasing such beneficial insects, rather than doing both simultaneously.
In the end, hobby gardeners have several steps to follow. First, promote beneficial insects and allow the garden a bit of wildness. Then, in case of acute infestation, use a stream of water. And only if that doesn’t suffice, use soft soap or plant infusions sparingly and targeted. It does work, as confirmed by Nabu, but it’s not a free pass for the entire garden.