Making potting soil

soeasytocraft

Does anyone make their own seed starting potting soil? I have always purchased for starting my seeds.

This year did not go well. The first bag killed all 40 of my beautifully freshly rooted Elderberry tree starts. The second "organic" brand was full of fungus gnats and the germination was not what it should have been. Very disappointed! My usual brand was finally back in stock to start all over. Sigh.

With this lack of success and all the toxic pollution in our environment perhaps we all need to create our own mix? I have pretty good garden soil and compost. Must admit to having lots of weed seeds that would be a real problem for seed starting.

Any experienced gardeners have suggestions where to start?

Tave

@soeasytocraft If your garden soil is good, try baking it. The smell of baking soil brings back fond memories of my Dad getting ready for spring and planting seeds.

I fill a deep baking sheet with good dirt and bake it until it gets to around 82-90C on a quick-read thermometer. That should kill all evil things, including weed seeds. Just make sure you don't scorch it by letting the temperature get too high. This site has alternative ways to sterilize your soil for seeds.

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/sterilizing-soil.htm

Torey

Good idea to bake the soil if there are lots of weed seeds.

I mix garden soil, compost and some peat. This works for me because our soil is quite alkaline so the peat helps acidify it a bit. If I am going to use it for seeding, I will put it through a sifter. But I don't bother if it is going to be in larger pots.

marjstratton

I have heard the cooking ones soil not only destroys the microorganisms but also destroys much of the soil structure. But I don't know what temperature they were taking it to.

Monek Marie

@marjstratton To cook soil you need to use a very low heat or you will kill microorganisms. I usually just put it in the oven and let the heat from pilot lights heat it. Or you can solarize it.

I have bought some pretty lously potting soil in the past so I tend to make my own. I have several recipes. Let me dig them out.

There are some good companies out there for soiless mix and potting soil but they have a price too and I like to save where I can.

soeasytocraft

@Denise Grant If you have a chance to share those recipes that would be great!

Thanks to all for the baking idea too. I will definitely try to be prepared for next spring! No more disappointments I hope!

Monek Marie

@soeasytocraft

One fast recipe: use equal part of coco coir or peat moss, compost, and perlite. I prefer coco coir or leaf mold over peat moss. Peat moss is in limited quantity so I find a replacement when I can.

I use my own compost and make leaf mold by collecting leaves, mowing over them first then putting in a black plastic bag with a little moisture and let set during winter months. By spring they should be broken down and are fantastice to use in place of peat.

Overall when I make potting soil I am looking for mixtures I have at home that I made that I know will work and will save me money. I also find my potting soil works better than store bought.

I'll post a few more recipes in a bit.

Tave

@marjstratton This is from the Gardening Knowhow article - "Place a meat (or candy) thermometer into the center and bake at 180 to 200 degrees F. (82-93 C.) for at least 30 minutes, or when soil temp reaches 180 degrees F. (82 C.). Anything higher than that can produce toxins."

You're right; we need to be careful not to overheat the soil to preserve its structure. Once the seedlings are strong enough to be planted outside or in a pot, the microorganisms will reestablish themselves. However, seedlings that die from damping off or weeds choking them out can't be resurrected. Sometimes, it's a matter of choosing the lesser evil.

gardneto76

I often mix a seed starting bag with more coco core & perlite. I occasionally add in some compost but only if it is really broken down. I have found I am more successful at starting seeds if I add in the starting bag. Once my starts are going they transplant well into my normal compost filled pots. I have not tried baking my compost, as hubby thinks I am crazy when I mentioned it to him. Plus he bought the seed starting mix for me. 😁😂

jowitt.europe

What an interesting discussion. And a useful one. Earlier I used my compost, recently I mix my garden soil with some bought garden soil. The young plants Grow very well, so I continue this practice, but now, following this discussion I am just thinking, why not return to my own starting soil again.

I have never tried heating soil. I am also worried about destroying the structure and microorganisms. When I come to thinking about weeding... well, I am not very much against it. And, as I do not destroy the seeds by heating, I do not have to sow many plants, especially herbs and eatable weeds and I can share or exchange them with my herbal friends.

soeasytocraft

@Tave Thanks for the very interesting link to the article on sterilising soil. It might be fun to try a pressure cooker using steam.

@Denise Grant Thanks for the recipe! Lots of leaves here so will definitely gather some come fall. I have never ever seen Coco coir for sale in our area. Must be to close to the North Pole for that. 😂This almost makes me excited for fall! 😁

dipat2005

Thanks for all of the interesting ideas. I used to make my own soil but found a company here that has just the perfect combination for me.

marjstratton

@Denise Grant and @Tave, thank you for the information. I am trying to resurrect some used potting soil for and use it for some of my indoor plants this year and have been a bit worried about what may be in some of that soil. I don't have a functional oven except for my little toaster oven which wouldn't do much soil. Maybe I'll try my yogurt method. Put some jars of hot water in a cooler to incubate it.

Owl

I read somewhere about mixing equal parts castings and coir for potting up seedlings and it said that they won’t need fertilizer until they are ready to plant outside. It made great sense to me because I’m famous for killing my seedlings with fertilizer. I have an urban worm bag that I just started last fall so I don’t have enough castings yet so I bought a cheap bag of castings and mixed in some of the fresh castings to add the microbe population and then mixed it with coir and it did wonderful. I have been really impressed by the fast growth and lack of bugs and weeds that I usually have to contend with. Great discussion!

Monek Marie

@Owl Worm casting are known for help with controlling insects and overall health of a plant.