The containers for my fall crops already have fungus gnats. Last year I tried nematodes and yellow sticky traps, both of which didn’t work. This weekend I saw my local nursery sells bags of cedar sawdust - it smells SO nice, and I think it would repel the fungus gnats.
The nagging problem is that cedar IS EXCELLENT at repelling insects and fungus. I’m a container gardener and from year to year (after thoroughly drying it to disinfect it) reuse my potting soil. And since I live in the balmy, humid south, I also use cedar oil on the wood in my closets and cupboards to prevent insects and mold … it’s expensive, but really works.
From browsing other threads on this site, I see that many people here are aware of the importance of biologically alive soil. Especially for those of you growing on land previously used with toxic plants like tobacco, or eucalyptus, what are your thoughts about cedar?
Cedar seems to be a general fungicide, and I see from the posts here many people are aware about the importance of mycorrhizal fungi (Mycorrhizae! Myco what?? – The Garden Professors™ , https://www.xtreme-gardening.com/mykos-mycorrhizae , for the uninitiated). So there is the qualm about likely killing the mycorrhizal fungi, plus I pay extra for fertilizer that has other bio active micro lifeforms (bla bla, whatever the fertilizer bags proclaim).
Once I add cedar sawdust to my soil, even if it is dusting on the tops of my pots of seedlings, there is no getting it out of my closed system!
Information? Thoughts?
PS Melon, I remember you using Mosquito bits for fungus gnats … if you happen to wander by, how much do you use and how do you apply it?
ive used cedar sawdust mulch for years. if you used alot of it maybe it could be a problem over time but a little is ok. i find over time the rain leaches the oils from the wood and at that point it composts about the same as any other evergreen wood. buried fresh and green would probably cause issues but I’ve never done it. i have a cedar mill down the road i get mine for free. i use in the chicken coops also and it then rots down in 2 years when put out mixed with chic. manure. what i get is small shavings, not fine sawdust though. coarser its less likely to compact and become hydrophobic on you.
I grew up in Humboldt where the area’s biggest crop needs to be organic and mold/mildew/bug free. The best way to obtain this is with neem cake aka neem seed meal. It does not harm beneficials and adds some nutrients. I finally got rid of fungus gnats and ants in my green house by liberally feeding all pots, still have happy worms.
I put a few scoops into the watering cans and let it sit for at least half an hour before i water the plants with it. I also just dump some everywhere that has standing water and leave it in my watering cans most times until i feel the need to rinse them out.
From what I’ve read, it’s safe for animals and humans for the most part so i don’t mind having it around.
When i root things, i also put some in a water bottle and poke holes in it or stick some in squirt bottles and water my cuttings with it.
People forget that fungus gnat larva also eat roots so rooting cuttings can be eaten by larva if not careful. I found this out with growing amaryllis indoor once.
One application seems to work for a long time lol. Sometimes I’ll throw it into the grass too when I’m fed up with catching them in my hair during the summer months. In the grass they seem to work for a month or so depending on how moist the soil is. Doesn’t seem to affect the worms or any other creatures in the grass
Unfortunately I can’t have a compost pile.
I’d be adding fresh cedar and once it is in the system there is no getting it out. Years ago when I did have a compost pile I remember you couldn’t add poison ivy to the pile - the organic matter would compost fine, but the itchy oil did not. I’m thinking I better skip the cedar idea until I can move and have a bigger garden.
Oooh! Today I recovered the dirt from a pepper plant that was doing poorly and found the pot had a huge ants nest in it. Let them eat Neem Cake, right?! Thank you for this!!
Oh, you water with it - that’s easy! They sell this stuff at Home Depot, I’ll get some tomorrow.
Stupid fungus gnats decimate my carrots and onions seedlings, and make my other seedlings have a hard time getting started in life.
ive been mulching with cedar for nearly a decade. i just kept piling it on 3in. at a time every spring. this was fresh from the mill and has had no undesired effects. the oils that leach out musnt have much effect going into the soil as if you dig under it into the soil, its full of worms. don’t think it sticks around like juglone. probably turns volatile and off gases on warm days.it also seems to rot at a similar rate to other types of woodchips I’ve used which surprised me.
I mulched a large ornamental bed with cedar trees that I chipped up myself. There were zero issues with the health of the plants, other than being happy about the moisture retention.
I scored five bags of cedar shavings and trimmings probably from someone’s furniture build project. Heaped it around my peach trees hoping it’ll keep away some of the baddies for peaches, for a few years anyway. 10 months out the peach trees love it still.
