Natural Insect Control: Aphids.
No doubt about it, aphids are a pain in the neck, especially if they get into your greenhouse. Once inside, natural predators can’t get at them, so the only alternative is to put ladybugs in your greenhouse or use sprays. Just knocking aphids off with a strong blast of water doesn’t really cut it, so we listed some alternatives below for homemade sprays to use on r aphids.
Tomato Leaf Spray:
Tomato plants, as members of the nightshade family, contain toxic compounds called alkaloids in their leaves. When the leaves of tomato plants are chopped, they release their alkaloids. When the alkaloids are suspended and diluted with water, they make an easy to use spray that is toxic to aphids, but still safe around plants and humans.
To make tomato leaf spray, simply soak one to two cups of chopped tomato leaves in two cups of warm water. Let it steep overnight. Strain the leaves out of the liquid using cheesecloth or a fine strainer. Add another one to two cups of water to the liquid and add it to a spray bottle.
Spray the stems and foliage of the infested plant with the spray, paying special attention to the undersides of leaves, where aphids most commonly congregate.
Caution: While this spray is very safe for humans, some people are allergic to members of the nightshade family. If you are one of them, use care in making and applying this spray.
Garlic Oil Spray:
This works against aphids but may also kill ladybugs and other beneficials. Using it in a greenhouse would be fine if you don’t have any beneficial insects you have relocated there. To make garlic oil spray, mince or finely chop three to four cloves of garlic, and add them to two teaspoons of mineral oil. Let this mixture sit for 24 hours. Strain out the garlic pieces, and add the remaining liquid to one pint of water. Add one teaspoon of liquid dish soap. This mixture can be refrigerated and used as needed. When you need to spray, use two tablespoons of the mixture added to one pint of water in a spray bottle. Shake up before spraying to mix the oil with the water.
To use your garlic oil spray, first test by spraying an inconspicuous part of the plant to see if your mixture harms it at all. If there are no signs of yellowing or other leaf damage after a day or two, it is safe to use. If there is leaf damage, dilute the mixture with more water and try the test again.
This natural aphid pesticide works as an instant remedy, killing the aphids on contact. To make this natural pesticide, grate the rind of a large lemon. Boil it in enough water to fill a garden spray bottle. Let the mixture sit overnight. Strain the liquid into the garden spray bottle. Spray the aphids and larvae directly.
While vinegar sprays work well against many types of insect infestations, some delicate plants may be killed by it as well. Start with a diluted solution of 10% vinegar to 90% water and spray on just a couple leaves of the infected plant and wait approximately 3-4 days to see if the leaf on the plant dies. If so, try the lemon or tomato leaf sprays instead.