Shinzy
Full Member
Posts: 12
Joined: Tue Jan 29, 2013 12:02 pm
Location: Texas

Gnats and small insects in indoor garden?

I've had my indoor garden doing quite nicely until a few weeks ago, when I noticed black specks on my onion stalks. Around the specks, the stalk would dry out, and it spread until the whole thing was covered in tiny black specks and the entire onion plant was dry and shriveled.

They are still green (very pale), no brown spots, and the bulbs look fine and white, but have all shrunk considerably.

The gnats have been getting out of control in my garden area, and when I was examining one of the onion stalks I noticed hundreds of tiny insects that are nearly invisible and pale yellow running up and down the stalks.

Could these be what are causing the onions to do this? And how do I stop them? I've already treated all my pots with an organic pesticide/fungicide spray and it doesn't seem to be helping.

User avatar
rainbowgardener
Super Green Thumb
Posts: 25303
Joined: Sun Feb 15, 2009 11:04 pm
Location: TN/GA 7b

Sounds like you have maybe both fungus gnats and aphids, or possibly just two kinds of aphids. Either way the gnats/aphids especially in big numbers like that can definitely damage your seedlings.

Try soapy water spray (with real soap not detergent) for the aphids. If you have fungus gnats as well, the first step is to let the soil dry out as much as you can between waterings - the gnats need moisture. Try putting a small bowl of soapy water next to where you see the black gnat-like bugs.

Since it sounds like you have a bad infestation already, you might start by just giving your plants a good cleansing. Wrap the pot/soil in plastic wrap to hold the soil in and rinse the plants off well under running water in the sink, get all the bugs off.
Twitter account I manage for local Sierra Club: https://twitter.com/CherokeeGroupSC Facebook page I manage for them: https://www.facebook.com/groups/65310596576/ Come and find me and lots of great information, inspiration

Shinzy
Full Member
Posts: 12
Joined: Tue Jan 29, 2013 12:02 pm
Location: Texas

Thank you very much for the information, rainbowgardener!

What should be the proper soap to water mix? I want to make sure I don't overdo it with the soap.

Unfortunately, I've already pulled up my plants, so I can't experiment with them. I'm washing out the containers now and am going to try replanting as soon as I clean the area to get any remaining bugs.

The good news is my basil plant seems to be just fine, and isn't being affected by any of this! It's been moved to another area of the house with lots of sunshine.

User avatar
skiingjeff
Green Thumb
Posts: 383
Joined: Sun Apr 01, 2012 8:22 pm
Location: Western Massachusetts Zone 6a

Shinzy wrote: What should be the proper soap to water mix? I want to make sure I don't overdo it with the soap.
The mixture I've seen most used is 1 1/2 -2 teaspoons to one quart of water. Good Luck! :)

imafan26
Mod
Posts: 11425
Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

I get black aphids on my onions sometimes, but it is usually when they are in distress. They are either old, over watered (rain), or over crowded.

The lady bugs don't seem to like black aphids much on onions.

Aphids are usually are on old or sick plants. I just pull the onions and rotate them to another part of the garden. If the weather is still cool, I will plant nasturtiums in its' place as a trap plant.

Indoors, I would do a good spring cleaning of the area. Sanitize your benches, control the ants and get rid of the infested plants. Plant a few nasturtiums and put it in place where the onions were. Nasturtiums are a trap plant for black aphids, and can be used as a sentinel plant. Isolate any plants that you are trying to save so they won't bring the problems back after you clean the area. I myself, would not try to save any. From experience, I have learned it is easier to start over, in a different location and with better air and less water.

Below is a link to a recipe for a homemade soap solution. I have also blasted them off with water, but it is hard to get them all.

https://urbanfarmgirl.hubpages.com/hub/G ... -Pesticide
Happy gardening in Hawaii. Gardens are where people grow.

Shinzy
Full Member
Posts: 12
Joined: Tue Jan 29, 2013 12:02 pm
Location: Texas

Thank you all for the information!

First off I'd like to say that the only detergent free soap available in my area is in bar form. I've used a cheese grater to grate off some of the bar, and mixed it with hot water to put in my water bottle. The only trouble I'm having with it is that after a few hours, the soap congeals at the top of the bottle and I have to shake it very hard for a long time before it evens out again.

Second, I'd like to know more about planting a "trap plant". Nasturtiums were mentioned, does that mean any one of the cabbage plants, or a certain one? And will the pests kill it, or will it keep them at bay?

I've already taken all the infected plants out, washed the containers and area they were in, and have replanted with fresh soil.

User avatar
rainbowgardener
Super Green Thumb
Posts: 25303
Joined: Sun Feb 15, 2009 11:04 pm
Location: TN/GA 7b

If you go to a drugstore, they probably have Dr. Brunners which is pure liquid soap, or Murphy's oil soap, or Ivory soap flakes.
/ edin

" Nasturtiums were mentioned, does that mean any one of the cabbage plants, or a certain one?" :?: :?: Were you thinking nasturtiums are cabbages? Nasturtium is a flowering ornamental/ edible plant (vining/ sprawling) related to watercress.

Nasturtium is supposed to be a magnet for aphids (although I haven't really seen that, when I have grown it). That makes it a trap crop because the aphids will congregate on the nasturtium and not bother your other plants (much). Then you can just deal with them there, either with soapy water or just by squishing. Aphids are slow and stupid and will just sit there and let you squish them.
Twitter account I manage for local Sierra Club: https://twitter.com/CherokeeGroupSC Facebook page I manage for them: https://www.facebook.com/groups/65310596576/ Come and find me and lots of great information, inspiration

Shinzy
Full Member
Posts: 12
Joined: Tue Jan 29, 2013 12:02 pm
Location: Texas

I'm sorry, for some reason the light research I did online turned up 'nasturtiums' as being a sort of cabbage. Thanks for the advice on how to use it as a trap plant, though :) This is interesting, if I can find some seeds or a seedling I definitely want to put it with the rest of my plants.

Right now I am using Ivory soap, just having to grind it up myself. If I have any trouble with it I'll look for those brands you mentioned :)

imafan26
Mod
Posts: 11425
Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

Nasturtiums trap mostly black aphids. Black aphids like to go after onions, and cowpeas. If there aren't any black aphids around the nasturtiums will also be relatively clean too.

As a bonus the leaves, seeds, and flowers are edible. I don't care for them myself, it is too peppery.

https://bioweb.uwlax.edu/bio203/s2012/st ... ctions.htm
Happy gardening in Hawaii. Gardens are where people grow.

pow wow
Senior Member
Posts: 227
Joined: Tue Mar 13, 2012 1:55 pm
Location: Alberta Canada

Re: Gnats and small insects in indoor garden?

The best solution that I know and use is the yellow sticky traps. You must have them south of the 49th. Little yellow cards that are sticky on one side. You bend them and put them on these plastic sticks that you stick into the soil. Gnats really go for yellow.
If your garden centres don't have them you can use any yellow paper or card board with some liquid honey or something clear and sticky smeared on it. Trust me on this, it works well and the fungus gnat population will decline down to zero.

tomc
Super Green Thumb
Posts: 2665
Joined: Sun Apr 10, 2011 6:52 am
Location: SE-OH USA Zone 6-A

Re: Gnats and small insects in indoor garden?

Doctor Bonner's liquid (try a health food store) soaps, Ivory also makes a (try piggly-wiggly) liquid soap. To name two.
Think like a tree
© 2016 Invisable Inc.

Greens
Full Member
Posts: 53
Joined: Fri Apr 05, 2013 6:52 am
Location: Indiana

Re: Gnats and small insects in indoor garden?

A lot of your problem could be your setup inside. Make sure you have a oscillating fan blowing softly over your plants. Its difficult for insects to get comfortable if there is good air circulation. As mentioned earlier, allow the medium to dry out well. This sometimes means not watering for a week or two. Another pest indoor growers face are mites. These are small period sized bugs that huddle up together on the underside of leaves laying eggs everywhere including the soil. In short they feed on the plant. They also multiply rapidly like fungus gnats. Spider mites sometimes can give tell tale signs of theyre presence by spinning webs as well. This would be pretty noticable. Neem, crab shell meal, soapy water, etc. I would try all and pray something works.
Indiana is:
Cold and Wet

imafan26
Mod
Posts: 11425
Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

Re: Gnats and small insects in indoor garden?

Gnats are related to vinegar flies (fruit flies). Leave a container of vinegar to attract them, you can make a cone at the top of the container with a coffee filter with the bottom tip of the cone snipped out. That way the flies go into the container and cannot get out. They will drown in the vinegar.

There are also light traps. The ones I have seen use UV light bulbs and a sticky trap. The gnats were attracted to the light and trapped by the sticky paper.

Cleaning the area and drying out the plants should help fix the problem. Run a fan to help dry out the soil and keep the gnats from landing.
Happy gardening in Hawaii. Gardens are where people grow.

sepeters
Senior Member
Posts: 266
Joined: Sun Jan 06, 2013 3:24 pm
Location: AZ, zone 9

Re: Gnats and small insects in indoor garden?

Is there some sort of soil amendment that discourages soil gnats? I up-potted my boyfriend's office plants for him a while back and he says he hasn't seen any gnats since then. I recently dropped off a couple gallons of worm poo tea at his office and he made me take "pest tour" showing me how everyone else had gnats in their plants. Some of them were bone dry and as soon as I poured the tea in them the bugs came swarming out. The only answer I could give him was that my dirt was magic. :> Anyone got a real answer?

User avatar
rainbowgardener
Super Green Thumb
Posts: 25303
Joined: Sun Feb 15, 2009 11:04 pm
Location: TN/GA 7b

Re: Gnats and small insects in indoor garden?

cinnamon. It's a natural anti-fungal that controls the fungus the gnats feed on. I just put a little bit of cinnamon in the water I water with and never have trouble with fungus gnats or damping off.

I quit using the cinnamon for awhile recently, because my seedlings were big, past the stage where you have to worry about damping off. Sure enough after maybe a week or so of no cinnamon, the first fungus gnats showed up! It's one version of a controlled experiment: no treatment, treatment, no treatment, applied to the same subject group. Looks like pretty good evidence to me.
Twitter account I manage for local Sierra Club: https://twitter.com/CherokeeGroupSC Facebook page I manage for them: https://www.facebook.com/groups/65310596576/ Come and find me and lots of great information, inspiration

imafan26
Mod
Posts: 11425
Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

Re: Gnats and small insects in indoor garden?

From what I have read. Most of the problems stems from over watering and not from intrinsically bad soil.
Happy gardening in Hawaii. Gardens are where people grow.

User avatar
rainbowgardener
Super Green Thumb
Posts: 25303
Joined: Sun Feb 15, 2009 11:04 pm
Location: TN/GA 7b

Re: Gnats and small insects in indoor garden?

Well, the problems arise from the conditions of indoor gardening - continued moisture and limited air circulation. It isn't exactly over-watering in the sense that you can't really let seeds/ seedlings dry out. I never have problems with the fungus gnats or other bugs/diseases with my regular house plants, because I let them dry out thoroughly in between waterings. But can't do that with the seedlings. But yes, it is the conditions, not the soil.
Twitter account I manage for local Sierra Club: https://twitter.com/CherokeeGroupSC Facebook page I manage for them: https://www.facebook.com/groups/65310596576/ Come and find me and lots of great information, inspiration

sepeters
Senior Member
Posts: 266
Joined: Sun Jan 06, 2013 3:24 pm
Location: AZ, zone 9

Re: Gnats and small insects in indoor garden?

That sounds perfect for the office plants! Thanks, RBG!

Return to “Organic Insect and Plant Disease Control”