Baja_Costero said:Yes, that is an instruction for installing plants in the ground. Mixing potting soil with native soil helps the newly installed plant find its way from potting soil (where it grew up) to native soil (where it will end up). Rather than forcing the plant to make a hard transition, the mix you use to refill the hole gives it a sort of bridge to its endpoint.
Best explanation. Now I understand. FWIW, I'm doing mostly container gardening because the soil on our property is poor. Some spots I have revitalized with amendments, but containers are easier for me because the plants thrive in them. Well, mostly.
Let me put it another way. Potting soil is essentially sterile and you add some dilute fertilizer after the seeds have sprouted inside in it. Soil is microbial active with stuff that can harm a small seed but is beneficial to a growing plant.
Does that help any?
Yardenman said: I make a potting soil blend each year from peat, perlite, vermiculite and compost. A trashcan full each year. I seem to use it up each year. But that is for containers and seed cells.
NMoasis said: Okay, now I understand your question. We've had the debate about reusing potting soil several times in various threads and there are different opinions (from Always to Never) and different recipes and approaches. Yes it is confusing. Ask five gardeners and you'll get six answers!
I can only speak for myself. I reuse & refurbish mine—I have too many large pots to be constantly replacing it. Minus roots and not if the plant appeared diseased. I don't have a regular recipe. This year so far I've mixed in some new rich bagged soil, compost and slow release fertilizer. I'll adjust that depending on what I'm potting. Might add some coco coir for more water retention or perlite for more drainage.
There are YouTube videos about how to renew used soil. Some I've seen were so complicated it didn't seem worth the expense and hassle. I'd suggest finding one that seems workable for you. As long as your gutter compost is thoroughly decomposed it would be a good addition.
Kathy547 said: I have bags of garden soil, perlite, & poultry grit. I want to mix them to use in some containers outside & for some houseplants I need to repot. I have read different measurements but am leaning on 2 parts soil & 2 parts a mix of grit & perlite. (1) Does this seem right for a general purpose mix? (2) Anything else I should add?