I made up a small batch of coffee tea a couple of days, and sprayed it on a lot of my solarium plants potting media. There are always some fungus gnats associated with the media. I also found a plumeria that had a bit of webbing on its tips, so spider mites were there. I misted those tips. I think the tea got rid of the gnats and perhaps even the mites. I will apply the mix again in a couple of days for those insects and mites that might have been missed or hatched.

Thanks again for the tip, Tom.

Great, that's good to know, Ken! I'll be doing that soon.

I have one badly infested geranium plant that I did treat with the Bayer. Within 24 hours the area around the plant was full of dead aphids and whiteflies. Pretty impressive, but it's too deadly to use anymore. Now I have to figure out how to get rid of it. Would it go to our hazardous waste pickups?

I don't know the answer, Karen. Different localities have different regulations. Disposal probably would be listed on the label information and should be found on the web. You might want to call your sanitation department and ask how you should dispose of it.

I have been using the Bayer 3 in 1 for quite awhile in my plant room to kill mealy bugs on my succulents. It has never completely gotten rid of them even when I drenched the soil and sprayed it on them. It sets them back for a while but I usually have to dump the succulents eventually anyway. I really thank @cycadjungle for the information about the coffee. I went right down and took the coffee grounds out of my coffee maker and mixed up some spray and put grounds down on a plant that I had just noticed mealy bugs on.

I had just been considering getting rid of them because it was a constant struggle to try to deal with the bugs but the coffee idea gives me hope!

Susie, I've had to toss countless succulents due to horrible mealybug infestations. They are nearly impossible to get rid of. I really hope this coffee will work well. I just sprayed several of my plants with the coffee solution.

Isn't it maddening Karen! Especially ones that you have had a long time and have gotten big. If this coffee solution works without damaging the plants it would sure be useful for lots of things, even in the vegetable garden.

It is maddening. I think the mealbugs have given me the most grief. Aphids come next. So far I've managed to avoid the spider mites and scale....knock on wood! If it works, I'll be using it on everything around here.

It has only been five days, but I sprayed all the tips of my plumeria (inside the solarium) with the coffee-solution. A few of the tips had evidence of spider mites. So far the young plumeria leaves look great and the spiders haven't woven any webs. Thus, not only does the coffee appear to be gentle on leaves (plumeria leaves can be very sensitive to insecticides and miticides) but may even be effective on mites. Holy cow! No sign of fungus gnats in the soils either.

Thank you, cycadjungle, for the great tip about coffee ground tea. I have one question: how is that different from simply watered down leftover coffee? Is there a recipe or a ratio to use? I, too, fight white flies in my little greenhouse and don't like to use chemicals. I've always added coffee grounds when planting to combat our alkaline soil (and I recycle used filters in the bottom of pots to prevent soil loss). But I've never heard of spraying pests with it. I definitely want to try it!
And thanks to all of you for the info on Bayer. Sometimes reading the label doesn't tell the whole story.
I only have one species with an aphid infestation, climbing milkweed vine (cynanchum racemosum var. unifarium, Talayote). I let the aphids thrive on it because they draw ladybugs. The aphids haven't killed the vines; but if they jump to any other plants, I'll use coffee tea.

Charlotte, brewed coffee is acidic whereas re-used coffee grounds are pretty much neutral. I think during the brewing process, the acids are leached out by the steaming hot water. On acid-living plants, used coffee would be great.

Okay, Ken, this is fascinating. But I'm confused. So all this time that I've been adding used coffee grounds to my planting holes in hopes of increasing the acidity in the soil, it wasn't really doing that? I should have been pouring my leftover coffee on them instead? Okay... So how do I make the spray for aphids/whiteflies with coffee grounds? Do I steep them in cold water? I apologize for being a pest, but I really want to understand this issue.
And now you know how my grandson feels when I call him with a computer problem. :roll eyes:
Thanks for your patience.

This idea did not come from me. I just latched onto it, Charlotte. Yes, the coffee grounds we have been adding to our acid-loving plants did not benefit from the acidity. They benefited from the organic additive. I guess they benefitted.

I put a cup of grounds in a blender with a quart of water and blended it all for about a minute. Then I poured it through a fine-mesh sieve and then through several coffee filters. I tried to spray the mix obtained through the sieve but it clogged the nozzle up. Thus the coffee filters.

I also clogged my nozzle up by not filtering it first. Live and learn.

Okay, that helps a lot! I'll keep using the coffee grounds because I think they help with permeability - but I'll keep my leftover coffee, dilute it a bit, and use that to water plants. My soil is limestone/caliche so it needs all the help it can get.
Karen, sorry about your nozzle. Now we both know.
Thanks, Ken! I'm going to try this recipe tomorrow!

@drdawg When you said you put a cup of coffee ground in the blender. Was that used coffee grounds or fresh?
Also, does the brand matter? I used Pete's coffee, French dark roast

Mine was used grounds. I don't know about different coffees having different results. I grind my own coffee beans every morning and the grounds always go into a 2 qt. canister. When that canister is full it either goes around landscape plants or as part of my potting soil that I mix up in a wheelbarrow.

I just remembered I have a kurege so I think I'm out of luck here

For the Keurig, save the used pods, you could always dump out the used grounds from the pods into a small pot on the stove top filled with water, then steep for a while. Then blend and strain- I would think that would be the same idea.

I may have missed this, but does this work for scale too? I'm suspicious of my monstera......

I'm sorry I have been away for a few days. I was a vendor at a pepper festival this weekend and I have been working on my taxes for the last few days. Just to answer a few questions. Evan though it may work a little bit, blending grounds and showing will only work in a minimal way. You want to cook the alkaloids out of the grounds so the spray will be at high potency. You can cook it many ways. I do it slowly in my barrel. You can take the used grounds and just run it through the coffee machine over and over, until it liquid us real dark. How many times you need to brew it will depend on how many grounds you start with. You can put lots of grounds and cook them in water in a big pot until the water is tall dark. You would have to strain this mixture before you use it in a sprayer. As a direct contact spray, the coffee will kill mealy bugs, aphids, all kinds of scales, white flies, and spider mites. Tom