Help! We're almost out of potting soil/seed-starting mix!

There's just a bit left at the bottom of our last bag and we still have at least a couple more trays-worth of things that should really be started in flats and potted up before being transplanted outside. (We are at special risk if we catch COVID-19, so we have had to completely eliminate trips to any stores or the post office where our box is for now.) For those of you seeking to reduce or eliminate inputs as we are, what solutions/replacements do you have for a good seed-starting mix that you can find or make around the homestead or surrounding environs? Thank you for any help and guidance!

I've been using scoops of soil from the best part of the garden mixed with soil scraped from under piles of leaves. Quick & easy & it seems to be working well.

I never buy potting soil, I generally just mix some rich dirt with compost or composted manure I have here. Its what they do before they bag it and sell it to you anyway, so I skip the middle-man!

I started some goji berries from seed and learned they won't really like traditional peat-based soils, so I mixed my native soil with some perlite for the containers - working better than I thought. If you had some extra slow-release ferts on hand, it could be fine for most stuff.

Can you order some stuff online? I would look for:

Perlite, slow release fertilizer, and vermiculite (for starting seeds). All of these are light weight so shipping costs wouldn't be terrible.

I've also played around with the idea of starting seeds in kitty litter (without all the scents/chemicals), but haven't done it yet.

Or you could bake and screen some of your native soil and attempt to start seeds that way. I've never done it, but It's on my list of experiments.

Thank you for these quick responses!

I should say that I'm primarily concerned about using this to start picky seeds (I start less picky seeds in our soil, with some added compost if needed, maybe some sand, depending on the seed). But this would be for things that might need a sterile mix without weed seeds and not too dense, with some air space in it, for example, so that it can get a healthy start. Also, we don't have the ability to receive orders right now because it's not safe for us to go to our box at the post office in town, so we're pretty dependent on what we can find or make around home. Once it's alright to go out, and/or once we get our new mailbox installed closer to us, we'll have more options, of course.

We were particularly trying to brainstorm a replacement for vermiculite or perlite. A thought: There's lots of dried cow manure around here, and we've already played around with throwing it in the kiln while firing clay. It makes something a little like bubbly glass, and of course after being fired it's sterile. If we were to break that up into little pieces (which aren't too sharp, so in that way not exactly like glass), do y'all think that might fill the role of something like vermiculite or perlite? Is there something else similar that we might be able to make using the kiln during a regular firing? (We might do one tomorrow night anyway.)

Brandon, do you use an oven to bake soil? Without an oven (don't have one yet), could it be done either just exposed to the sun over the course of a few days -- potentially under a pane of glass -- or alternatively over an outside fire in a big dutch oven or covered oval roasting pan, you think? It seems like the kiln might be overkill for that. ;)

Thanks again!

I'm trying to conserve my seed starting mix as much as possible.  If it becomes necessary to move the seedlings into a larger container before moving them into the garden, I'm planning to recycle the soil from last year's containers.  Not the most ideal situation, but like you I am not interested in leaving my home right now.  Do you have access to sand?  That may help with the drainage issues.  

I'm also going to experiment with transplanting some of my more tender plants before the last frost date.  It's a risk and a lot of work to cover and uncover the beds every day but I think I can make it work.  

In my area, Walmart grocery is delivering Miracle-Grow potting mix. As far as seed starting mix, i always use expanded coconut coir.

If you can order a bag of peat moss. Do a 50:50 mix of the peat moss and your garden soil. This is basically store bought potting soil. If you are going to not transplant and just grow in pots, then add a cup of general purpose fertilizer to the batch, if you are making a wheel barrel sized batch of potting soil. Also, add a handful of dolomitic lime to the batch. Fully composted material can be added as well.

Here in Michigan nurseries have been deemed nonessential, yet liquor stores and marijuana shops are still open. I would like it if steps were being made to encourage gardening. I guess they want people to continue to strain the grocery stores and supply chains. I guess you can see what brings in the most taxes.

Anyways, the info in this thread will be helpful for potential gardeners.
I think I will start extra veggies and try to give them away.

Sorry if I got too political for you.

Mike Barkley wrote:I've been using scoops of soil from the best part of the garden mixed with soil scraped from under piles of leaves. Quick & easy & it seems to be working well.

This is the best way to get some "potting soil".  Find some trees that are mostly in the shade where grass will not grow.  The leaf litter under them can be scraped back to exposed what is commonly called leaf mold.  It is a form of natural compost and you can grow in it without doing anything else.

Another idea is to use coffee grounds.  I don't know if anyone has tried using them straight so this would be a great experiment. If nothing else mix the leaf mold with the coffee grounds.

Smashed up char would be overkill, but a good substitute for perlite/vermiculite.  

Here is the link to a thread discussing the crushing of said char.  When done with it, you've got biochar!

Justin Gerardot wrote:Here in Michigan nurseries have been deemed nonessential, yet liquor stores and marijuana shops are still open. I would like it if steps were being made to encourage gardening. I guess they want people to continue to strain the grocery stores and supply chains. I guess you can see what brings in the most taxes.

Anyways, the info in this thread will be helpful for potential gardeners.
I think I will start extra veggies and try to give them away.

Sorry if I got too political for you.

I have been struggling with this philosophy lately. Even though garden goods have been deemed as non essential the stores that sell these products are still open. Therefore, I was still able to get supplies. I noticed that Tractor Supply was a lot less busy than Home Depot here. But that may not be the case where you are. I wonder if farm supply stores are still open where you are, I would highly doubt they would close these, considering farmers need access to them to grow food.

Beth Wilder wrote:
Brandon, do you use an oven to bake soil? Without an oven (don't have one yet), could it be done either just exposed to the sun over the course of a few days -- potentially under a pane of glass -- or alternatively over an outside fire in a big dutch oven or covered oval roasting pan, you think? It seems like the kiln might be overkill for that. ;)

Thanks again!

That's a tough one. If you don't have an oven, you likely don't have a microwave either. And the pane of glass likely won't work if it's still chilly outside.

You could try chemical sanitation (like alcohol and letting it evaporate), H2O2 would probably be too weak. Or, maybe boiling? Anything to get the temp as high as you can without changing the chemistry - which I imagine the kiln would do.  Your roasting pan idea seems like it would work.

You can put an ad on your local craigslist for someone to get what you need for you and drop it somewhere on your property to keep safe distancing. You can also ask them to sanitize whatever they are getting. One is able to prepay at the local big box stores, at least at the Lowe's and Home Depots around where we live, and then all you have to do is pay the person who is picking it up for you. You don't need much so anyone with a car can do the run. People are happy to do these types of errands at a very reasonable cost these days.

Brandon McCarthy wrote:That's a tough one. If you don't have an oven, you likely don't have a microwave either. And the pane of glass likely won't work if it's still chilly outside.

You could try chemical sanitation (like alcohol and letting it evaporate), H2O2 would probably be too weak. Or, maybe boiling? Anything to get the temp as high as you can without changing the chemistry - which I imagine the kiln would do.  Your roasting pan idea seems like it would work.

Thanks! Yeah, definitely no microwave. Anything using electricity to create heat doesn't work too well on our relatively small-scale solar system (which, I should clarify, is more than enough for our needs in almost every instance -- we're not suffering in any way, we just don't expect to do things like run an electric kettle or microwave). On the plus side, it's actually pretty warm here at this time of year -- high of 81F today! low of 45F tonight, but we could definitely still get another frost between now and May 15 -- and quite sunny most days. We're rationing our remaining rubbing alcohol and Everclear so that we'll have it for our hands, doorknobs, etc. in case we do need to go out in an emergency, as well as, in the latter case, for making home remedies. So I think I'll try some soil in a black pan under glass during the day and some in a roasting pan on the outside stove at night. I'll let y'all know how it goes. Thanks again!

How important is it to sanitize the soil?  I plant seeds directly into the soil outdoors so how is it different if I am planting inside?

Another option to sanitize the soil might be just using a light.  Kind of like the kids easy bake oven that will actually bake things?  Use a light over the soil in a confined space so it will heat up.

First time I hit the quote thingy.
Well Michigander. From north Saginaw Bay area originally. Like the growing season better in south central VA. But... Our trick was to take some of the black sandy loan soil we had and bake it for a bit on ol trays at 200° And yes it was inside  our kitchen oven an stunk up the house. Used (And still do) 4' florescent lights, 1 cool and 1 kitchen/bath bulb to get a decent spectrum of light. Wife is off the truck to keep her Lupus down and work on property. We give away bout 30% of our garden last year. Expanded garden this year. Got some gonzo local heirloom beans. Talked the neighbor into continuing his charity bean acre. He is 77.i tape to be able to take over for him soon. And switch to natural methods.
God bless.

Justin Gerardot wrote:Here in Michigan nurseries have been deemed nonessential, yet liquor stores and marijuana shops are still open. I would like it if steps were being made to encourage gardening. I guess they want people to continue to strain the grocery stores and supply chains. I guess you can see what brings in the most taxes.

Anyways, the info in this thread will be helpful for potential gardeners.
I think I will start extra veggies and try to give them away.

Sorry if I got too political for you.

Anne Miller wrote:How important is it to sanitize the soil?  I plant seeds directly into the soil outdoors so how is it different if I am planting inside?

Another option to sanitize the soil might be just using a light.  Kind of like the kids easy bake oven that will actually bake things?  Use a light over the soil in a confined space so it will heat up.

That's what I was wondering too. I just trick the weed seeds in my potting soil into germinating too early by watering the soil and keeping it in a warm and dark location for a week or two. While there might be bad microbes in the soil, sterilizing it would also kill the good ones.

John Wolfram wrote:

That's what I was wondering too. I just trick the weed seeds in my potting soil into germinating too early by watering the soil and keeping it in a warm and dark location for a week or two. While there might be bad microbes in the soil, sterilizing it would also kill the good ones.

I think some people worry about damping off. My concern is that if you use sterile potting mix, there are no good microbes forcing people to use artificial fertilizers instead of compost or compost tea to feed their plants. Since molds are an issue in my ecosystem, I compromise. I use 3" deep pots (at least) and put mostly compost mixed with soil and a bit of perlite, a bit of ash from the woodstove, some vermiculite, and a bit of coir if it needs it to also help hold moisture. I put that mix in the bottom 3/4 of the pots and only use a thin layer of the sterile mix on top. Beth doesn't have the perlite or vermiculite, but using fresh char will steal the nutrients from the seedlings. If she can make char, I would suggest she mix it with water and the best compost she can and stir it for 3 days or so in a warm place and I've heard adding some molasses to help feed the microbes can help them multiply quickly. Then I'd scoop the char out and mix it with compost and soil and give it a try. She's suggested she's going to try sterilizing some soil, so I would also suggest she put mostly unsterilized soil in the pots first, and only use the sterilized soil for the top bit. So much also depends on the type of soil (I have to thin our heavy clay with something), how bad you think the weed seeds are in the soil, and how long the seeds you're planting will take to germinate. Some bottom heat can go a long way to helping seeds germinate at the short end of their window, but if you don't have a RMH bench to use (it's in my dreams!) I've resorted to an insulated container with hot water under seed trays (but I use small seed trays.)

Anne Miller wrote:How important is it to sanitize the soil?  I plant seeds directly into the soil outdoors so how is it different if I am planting inside?

Another option to sanitize the soil might be just using a light.  Kind of like the kids easy bake oven that will actually bake things?  Use a light over the soil in a confined space so it will heat up.

Could you not just poor boiling water on the batch of soil to be used? I think boiling water would kill any insect eggs in the soil.