Coffee spray/coffee grounds insecticide

[JohnAndSancho]

Dumb newbie question. 

 

All of my palms are in pots, most stay indoors especially now that it's winter. I've read lots of posts on here about using coffee as a natural insecticide, but not lots of details.

Does the coffee work like a systemic? How much should I dilute it?

 

I've spent more than I care to admit on insecticidal soap, but I know it only works on contact. 

 

We throw away so much coffee/grounds at work(Marriott) as we keep it hot and fresh in our lobby 24/7 and our industry has been impacted more by Covid19 than probably any other industry on the planet. 

 

Also, if I use the coffee grounds, can I bury them under the soil? I doubt my dog would get into it, but I don't want to take any chances. 

[Dartolution]

Definitely NOT a dumb question. 

Caffeine is toxic to insects, but since the brewing process removes the majority of caffeine coffee grounds are relatively "non-toxic."

I have read where people brew coffee - albeit cheap coffee haha - and allow it to cool and use as a ground/foliar spray but I myself have never attempted this. 

All I can say is that coffee is NOT going to work like a systemic, and that determining what insects you are trying to get under control would be more helpful to know.

It sounds like you are wanting something that has more of a residual effect... 

Generally in MY yard I use only organic insecticides with wonderful results. I use a combination of neem oil, spinosad(which is absolutely my favorite), insecticidal soap(or if I'm out a few drops of regular dawn dishwashing liquid), BT spray, and pyrethrins. 

I use these on a general 2 week rotation or in combination with each other and have VERY little insect issues. Nothing out of control, most everything in balance.

For things like earwigs, snails, and slugs I use Bonides bug and slug killer on the ground. It has worked perfectly well for me. 

 

I caution you on the use of systemics, especially on flowering plants/shrubs as some can translocate into the pollen and thereby kill friendly insects that we benefit from (i.e. Honeybees) as well as many others that are NOT pests. 

 

As far as your coffee grounds from work, if you can bring them home do so, and use them in your yard, pots, and planting beds, compost, veggie garden, and more. 

I use my coffee grounds in my yard, and all of the above to enrich the soil, and feed the earthworms (they seem to love them). This is a VERY good use of used coffee grounds.

You don't have to bury them under the soil, simply scatter them about wherever you want to enrich.

Used coffee grounds are fairly safe around pets (see ASPCA website and other resources) since the caffeine has been mostly removed, and it is unlikely that they will eat a large enough quantity to do any extensive damage. However, your pets, use your own judgement as far as that goes.

I hope this helps!

 

[Darold Petty]

8 minutes ago, Dartolution said:

 

 

I caution you on the use of systemics, especially on flowering plants/shrubs as some can translocate into the pollen and thereby kill friendly insects that we benefit from (i.e. Honeybees) as well as many others that are NOT pests. 

 

 

Yes, exactly.  Thanks for your great summation.  I don't use systemics on outdoor plants because I can't risk poisoning hummingbirds as well as insects. 

[Dartolution]

@Darold Petty absolutely not. I have potted plants (heliconias, pachystachys, justicia etc...) that I do not use systemics on either for that exact reason. The pachystachys is my local hummingbirds favorite shrub to drink from besides the canna lilies. They get grown in an organic mix, and fertilized with espoma tone products mostly with regular feedings of seaweed and molasses. 

 

[Johnny Palmseed]

@Dartolution has summed it up pretty well. I have found coffee grounds to be a deterrent but I doubt it would be anything more than that. I have specifically used them on our “coontie palms” which is a Zamia. They tend to get loaded up with scale and mealy bugs. Coffee grounds help limit the buildup but I doubt any are killed from it. Before COVID, I would bring home grounds from work and dump them all over. Starbucks used to give away “garden grounds” but I don’t know if they still do. I would say if you have access and are willing, dump as much as you want in your yard. It’s organic and you will be unlikely to do any harm.

[JohnAndSancho]

I've been fighting what I think are mealybugs, and i have a lot of plants in a really small space. I haven't seen any visible bugs, cotton, webbing or anything lately, but my 2 cat palms have a really slightly gritty texture to the leaves, and one of them is really going through some things. 

 

Plus all the coffee and grounds are free lol 

[Patrick]

1 hour ago, JohnAndSancho said:

I've been fighting what I think are mealybugs, and i have a lot of plants in a really small space. I haven't seen any visible bugs, cotton, webbing or anything lately, but my 2 cat palms have a really slightly gritty texture to the leaves, and one of them is really going through some things. 

 

Plus all the coffee and grounds are free lol 

Gritty leaves makes me think spider mites... Soapy water takes them out pretty well, or even just a solid rinse with the hose.

[Merlyn]

Caffeine is a systemic, just like neonicotinoids are systemic.  Tom Broome wrote about using coffee grounds to combat CAS (Cycad Aulacaspis Scale).  In my experiments there is no doubt that it works to limit cycad scale and prevent reinfestation, but there's probably not enough caffeine in my used espresso grounds to eradicate it from an infested Revoluta. 

I have three clusters of small Revoluta up front, across the street from my neighbor's heavily infested 5' tall trunking cluster.  I put lots of old espresso on three of them, a little bit on two of them, and none on the other three, in a space about 6 feet across.  The three with lots of espresso have no CAS, the others are mildly or moderately infested. 

A second experiment I did with one in a pot in the backyard.  It was heavily infested and gets espresso ground mulch on a regular basis.  The infestation is slightly less today than it was last year, but it's all still there.  As Johnny and Dartolution said, it's probably a deterrent but not truly useful for bug control.  However it does make a great high-nitrogen mulch!

Actually eliminating the CAS off of Revoluta took a soil drench of Dinotefuran (neonicotinoid) and foliar sprays of organophosphates (Acephate or Malathion) but the most effective treatment was simply washing them off with a strong hose sprayer.

 

[Dartolution]

@Merlyn How interesting! Are there any issues with using a soil drench of brewed coffee? Acidity issues? 

I've got to read up on this!

[Fallen Munk]

Be advised that caffeine inhibits germination and can stunt the growth of some plants.  And spent grounds still has a lot of caffeine in it.  I only use it after it is well composted.

[Merlyn]

1 hour ago, Dartolution said:

@Merlyn How interesting! Are there any issues with using a soil drench of brewed coffee? Acidity issues? 

I've got to read up on this!

I haven't tried any brewed coffee experiments, so I don't know about that.  Here's Broome's article on it.  I asked him about it when I was down at his nursery picking up some Encephalartos and Dioons, he said caffeine is just as effective as Dinotefuran but a lot cheaper.  I'd assume it has the same potentially negative side effects on pollinators, so best not to use it on any blooming plants.  http://www.cycad.org/documents/Broome-Coffee-2007.pdf