Black Aphids In a Greenhouse

by kbischoff
(Lafayette Hiill, Pa)

Our gardening club planted about 500 coneflowers in small pots that we are tending in a greenhouse. We intend to sell them in the Spring to raise money. Our problem: Black Aphids. We have tried spraying with Water with Dishwashing solution added but they are teeming with them still. What can we do to save the plants? Would moving them outside kill the aphids without killing the plants. They are now seedling sized.

Doug says that first of all using dishwashing solution is not something I ever recommend. Most of these are detergents and not soaps. And they often burn the heck out of plant (particularly) tender seedlings if not measured out properly.

Get some insecticidal soap (and stop trying to save money on this) :-) Mix it up at the recommended rate and spray as per the label directions. Cover top and bottom of leaves.

That should take care of your problem with the aphids.