Elliot Coleman has written that it takes time for starts to develop mycorrhizal relationships in cool soil which slows their establishment for lack of adequate phosphorous. I never searched for corroborating research to this, but if it’s true, having the right fungus in the potting mix might make a difference even for plants moved to normal soil with symbiotic fungus already in the mix. Of course, adding water soluble P would likely work also.
However, I do believe that if you added a small amount of compost to the mix or even garden soil you would get a similar result. I do this when I move peppers and toms into larger pots for the last sizing up before transplanting anyway… maybe one part compost to 3 of potting soil. Planting these species into cool soil is not helpful anyway… they just sit there until the soil warms up. By the time I put tomatoes in the ground they ae 3’ tall and holding a crop of green tomatoes. This vastly extends my harvest season. I don’t have enough indoor light to do quite the same for my peppers- they get much smaller containers.
We use Mykes root stimulator, but I haven’t done anything scientific to prove it works. My rationale is I’m in largely grassland area, so maybe the trees need the extra fungal boost if whatever in the ground isn’t forest adapted.
I’m starting some Castanea henryi seedlings and was searching for information on this species when I came upon the report linked below. Ever since I’ve been trying to figure out how to get some Boletus edulis spawn to mix into my potting soil. Just look at page 6 to see a comparison of seedlings grown with and without!
I’m not sure how good any of the pre-packaged products are and I believe that you may need to get specific species/types of mycorhizal associations going that works best with what you are growing. For instance, with chestnuts, I’ve seen other information that the mycorhizal association with puffballs can have a strong effect. But of course, B. edulis (porcini) are more delicious. Unfortunately, I couldn’t find a follow-up study that showed whether these seedlings were planted out and ultimately produced a crop of tasty mushrooms at the base of the trees down the line.
You may need to copy and paste this long URL to get it to work.
We moved into a new house just over a year ago and to have something to plant I ordered various cheap seeds off amazon that many were mixed for reviews on getting anything to sprout. I decided to try a myco product to help. For one packet of seeds I forgot to apply it to 1 out of 3 seedling trays. Every single seed grew except in that one tray I got nothing. I tried sprinkling some on top and watering it in, disturbing the soil, chilling them in the fridge overnight, exposing them to more light but nothing would make those seeds sprout when the entire rest of the packet all sprouted.
I’ve been sticking myco on everything since then and keep ending up with a higher germination rate than planned for as well as 100% transplant survival. A landscaping company said the only person they’ve never had to go back and replace trees or large bushes for always dusts the hole and plant roots in myco before they are put in the ground.
We have badly compacted heavy clay soil that has been sprayed with herbicides multiple times a year for who knows how many years before we moved in. I immediately noticed where ever the dogs dug up the soil in the yard there was a sour smell instead of normal dirt odors. It’s been bothering me since last spring. I spent last year adding soil organisms including bacteria, myco, and nematodes along with gypsum, humic acid, and charcoal.
A grapevine reappeared from where they used to grow until the previous home owners gave up on them and cut them all down. Several flowering plants no one remembered existing also suddenly exploded around the yard and up the side of the pool. I think the old fir tree my husband and his dad were certain needed chopped down is even showing some improvements. My husband commented on the amount of needles growing from the trunk now. I can’t figure out exactly what is wrong with it since it has no obvious damage or diseases besides losing nearly all it’s needles in the past and never recovering them but there are numerous possibilities of soil issues with compacted clay soil, a pool that has been drained into the yard every year (clay likes to stick to salts and chemicals), and “mulched” with round river pebbles around the trees and along the fenceline. In some places I had to dig nearly 2’ down to loosen enough of the soil encasing the rocks for soil testing.
Some soil definitely needs beneficial populations of fungi and bacteria restored. Most places used as a lawn for an extended period of time are likely to benefit even if not in as bad of condition as our current soil. Crop yields and growth of prairie restoration locations has been pretty convincingly improved by spraying products containing common soil bacteria. If those soil organisms are useful for restoring used land even when it’s near less disturbed wooded or wild growing areas then adding fungi seems it would also be likely to help.
You would probably achieve the same eventually with just adding organic material and compost but it will take longer. We did try scooping up a few plastic bins and buckets of soil from edges of woodlands and areas left to grow wild to help innoculate our yard with soil that had not been essentially sterilized by recent common lawn/garden practices.
More plant diversity also helps. Some plants encourage myco and the growth of various beneficial soil organisms. Grass and food crops generally do not. Clover and other legumes can help re-establish the microscopic life in the soil. A few herbs were also mentioned in various articles I read. Heal-All (Prunella vulgaris) is becoming popular to add with clover to lawns in order to keep the soil healthier and reduce additives and maintenance needed. Slowly the idea of single plant species lawns and some modern farming practices are being changed to restore depleted soil and reduce needed fertilizer and chemical applications. Part of the process is usually some method of recovering the destroyed populations of micro organisms as well as various larger soil dwellers.