All potting soils, unless sterilized, potentially harbor insects or their eggs. Since it is very costly to sterilize soils, very few are. All have hundreds of species of fungi, some potentially problematic, others of no consequence or beneficial. Most problem fungi are air born anyway, so as soon as a planting is established, it's no longer sterile - especially if the planting was established from a plant that didn't come from seeds personally planted

I've never had any issues with insects arriving in the soil that I know of, and the highly aerated soils are much more inhospitable to the fungi that cause root/crown/stem rots and other damping off diseases. Is it best to start seeds in a sterile medium - yes. Have I ever had a problem establishing seeds or cuttings in the 5:1:1 mix or the gritty mix - no, I haven't.

Also, soils IN pots are much less bug-friendly than soils in windrows or bags, and any bugs can usually be counted on to vacate the soil soon after your plantings are established. The other consideration is that, like me, the large fraction of growers growing in bark-based soils or in peaty soils amended with pine bark aren't reporting any incidences of bug problems.

Al

Ok good, also, with my current plants being in MG, the only insect problem I ever have is fungus gnats. From what I understand, they live in damp soils, and feed on decaying plant materials. They don't bother anything, but they can be annoying. Is the 5-1-1 mix going to be less hospitable to fungus gnats then MG??

Yes - all airy soils are much less hospitable to gnats because the soil surface dries quickly. If you water on an 'as needed' basis, you won't have a gnat problem.

Food for thought: The directive to water only 'as needed' begins to lose its imperative nature as soils open up. For instance, I water everything on a schedule. Albeit, I have plants on different schedules, but I have a little card in the basement that is marked like this: SU,Th,MO,FR,TU,SA. It tells me that I need to water most plants every 4 days, and I do - religiously. A few of those get watered every 2 days, and a VERY few in tiny, tiny pots get watered every day.
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As soil porosity increases, the PWT is reduced or disappears entirely. Since it is ONLY the PWT and associated anaerobic conditions accompanying it that the advice to 'water only as needed' is predicated upon, the advice is not applicable unless the reason for offering it is in play.

Al

I completely agree.

Fungus gnats are a non-issue in grit or bark-based mixes.

I do have an aphid problem indoors, but I don't think it's the bark....I think they're
on the Hoyas that hang in the maples during the Summer.

Josh

Perfect! My wife is going to be thrilled when I tell her that those annoying "fruit flies" are not going to be a problem anymore. I've never have aphid issues indoors, but man, do I have some serious aphid issues on my aspen trees in summer. That'd be the reason I don't put ANY plants outside in the summer anymore. That and once, I had a large jade outside, which I always did in summer. When I was about a foot away from the door while bringing it inside for the night in fall, a chipmunk jumped out of a whole it had dug in the soil. I didn't even notice it until the little critter popped out, but I can't even imagine what would have transpired later that day had that chipmunk made it into the house.

Joe

Great story, Joe! I do love chipmunks...in their proper environment, of course! ;-)

Another advantage of grit and bark-based mixes is the cleanliness of the mix when watering.
The water that flows out of the container - the effluent - isn't dark, tannic, and staining, as
you'd see from water draining through bagged soils composed of peat moss and other organics.

It's an all-around superior method of container growing.

Josh

I keep my bonsai plants up on growing benches all summer, and when winter bears down, I move them into the garage. I am at least 400 yards from a small creek that winds through the west side of the slope on our west. Imagine my surprise when I started into a repot on a conifer of some sort, early in the spring, only to discover a salamander still sleeping soundly in the soil!!! He must have flown up into the pot - I have no idea how he got there, as my benches are set on 4x6 wooden posts it would have had to climb to make its way to its winter quarters. Think it knew it was going to overwinter in a relatively snug garage when it chose it's spot? ;-)

Al

I had a fungus gnat issue on a plant and read on a thread here that watering with peppermint tea will kill them. I tried it once and have not seen any more 2 weeks later. I plan on going through a few more cycles though. I also sprayed the top of the soil with disinfectant because I had mold growing on the surface so that may have helped too. My plant (draceana) was not affected by either.

I also have a question similar to this topic - I re-potted a Sans that was in pre-packed potting soil and there were nasty, gross, milipedes in it. I'm extremely grossed out and creeped out by these things. If I do the gritty mix will this still possibly be an issue due to the bark? Otherwise I plan on doing all in-organic and treat it semi-hydroponically (sp).

It's the organic fraction of the soil that attracts them to the rotting plant matter in the first place. The gritty mix doesn't support large populations of the micro-organisms that rot vegetation, AND, the hydrocarbon chains the bark is made up of are rich in a lipid called suberin. Suberin is sometimes referred to as natures water repellent because it is so effective at stopping the effect that moisture has on decay. Suberin is also resistant to the oral secretions millipedes use to soften material before they eat it. What I'm getting at is, there isn't anything in the gritty mix to make millipedes want to stick around, so if you happen to find one hiding out under the pot, it's likely transitory and only there because it got caught out in the open when the sun came out & needed a quick hideout.

If you had mold growing on top of your soil, and gnats, we probably need to look at your watering habits and your soil. I'd be careful about spraying any disinfectants because the bacteriostats and types of fungicides they contain are often phytotoxic (plant poisons). If they aren't, the vehicle that carries them (the liquid that makes up most of the spray) could easily be.

Let me know if you need any help with the soil. It CAN be something of a pain to locate all the ingredients, but once you find/acquire them, you'll be very glad you did.

Al

Excellent - thanks. I plan on getting rid of that bad soil with the gnats and others ASAP but it's a pretty big pot and I'll probably have to get extra ingredients. I actually went ingredient shopping yesterday and had to get repti-bark because the true landscaping/nursery places are not open yet.

You might want to consider adding where you live and your USDA zone to the user info that shows up in your posts - to make it easier to help with specific advice. Maybe I can help you locate what you need. I've done it often enough that I'm pretty efficient at it. ;o)

Al

I tried a while ago but it didn't work, maybe it will work now. I'm in the Northern Chicago/Southern Wisconsin area! I know there are John Deere landscaping places around but that's about as much as I know so far!

Well, worst case scenario, I am in the SE Wisconsin area, I found my source! $4.99 for a 2 cubic foot bag, and they had a whole palet of it. You'd be driving a bit though, about 15 minutes north of Milwaukee.

Your biggest challenge will prolly be the bark, but I already know where you can get perfect, pre-screened fir bark - from the same place I buy mine - Oakhill gardens in Dundee (near Carpentersville), NW of CHI, The Turface should be available at any of the John Deere dealers. If not, let me know & I'll find it for you. All you need now is the grit. Call rural elevators (grain storage facilities) that also sell feeds, or feed stores that sound like they might cater to farmers (skip the chain outfits). Ask for Gran-I-Grit brand grit in grower size or #2 cherrystone. If they don't have it, ask if they know who does, then go on to the next on the list. If the regular yellow pages aren't helpful, the online yellow pages might be. That's usually the resource I use to help others find what they need.

Al

Since I switched to using the Gritty Mix, all signs of fungus gnats have disappeared. It's not the type of environment they prefer or can thrive in, so they aren't present. No more annoying little gnats!

When I consider the sources of the ingredients I use, there's really no issue with undue insect, bacterial or fungal problems.

I still watch for spider mites or other tiny insects that like plant material... but I haven't had any issues.

Joe, I'm in Chicago and I found the grit at a Feed Store on Harlem, south of I-55 - I think it's in Summit. It's easy to find, though, just exit 1-55 at Harlem, go south, and it's on the right hand side in short order.

The bark is hard. It's a heck of a tramp for me to get to Oakhill, especially since I don't own a car! I've sometimes had luck at the big box stores, but usually not.

Less expensive than Reptibark for people who need small quanitites may be ordering either the finest grade of fir bark or the finest grade of New Zealand bark at Roberts Flower Supply online. Their price for the bag is the same as Oakhill, if I remember correctly, but you pay $12 for shipping. (that's if you buy the large bag) The best part is that it's perfectly uniform, perfectly sized and no screening is needed.

One of the things that rarely gets discussed is the fact that a plant's defense 'system' is linked directly to it's vitality. Vitality is roughly it's state of health. Plants are much like people, in that their energy levels, fitness, stress levels, all play a part in how able they are to resist things like insects and disease. Defense is energy driven, and the greater the amount of stored energy or the faster current energy is being produced and used (metabolism), the better able the plant is to resist stress and strain. We know an athlete's immune system operates at a higher level than that of an overweight couch potato.

Root health is also inextricably connected to plant health and vitality, and in that, connected directly to a plant's ability to resist the attacks of insects and disease. In the case of FGs, they are very closely associated with heavy soils and the over-watering that so often goes part & parcel with them, so changing soils and watering habits is key. At issue, is the problem of HOW to eliminate an environment that favors gnats w/o resorting to watering in sips to keep prolonged soil saturation out of the picture. The easiest way, of course, is to adopt a soil that eliminates the need to water in sips AND allows you to water copiously and still not be concerned about root rot OR gnats.

The HUGE added plus is that the highly aerated soils can at all times, even at container capacity (when fully saturated) provide a soil environment, the volume of which is always 100% root friendly, which brings us full circle to roots' connection to plant health/vitality and plants' ability to resist insects and disease.

I've posted these 'Whitcombisms' before. They were gleaned from the works of Dr Carl Whitcomb, PhD, who wrote what is probably the bible on growing plants in containers. Some "Whitcomb-isms":

"If the root system ain't happy, ain't no part of the plant happy"

"Roots control the tree, the stems and branches just think [not my emphasis] they are in charge."

"The more roots to share the load, the faster the dirty work gets done"

"Roots provide the fuel for the plant engines we call leaves"

"Each root tip casts a vote to decide what the top will be allowed to do"

"Top growth gets all the glory, but the roots do all the dirty work"

He also notes that "Stress can ALWAYS be measured in the root system before symptoms appear in the top [of the plant]".

Al