Peat in container mix

[hiker_]

My neighbor gave me some "container mix" which I used to pot up my tomato seedlings. They seem to like it, so I figured I'd make some more of her recipe for the determinates I'm planning to keep in containers.

It is:

2 5 gal buckets sphagnum peat
1 5 gal bucket perlite
1 5 gal bucket vermiculite
1 cup dolomitic lime

Has anyone used this kind of container mix with good results?

And...

The mix she gave me was already mixed. And moistened.

I now have a bale of not at all moistened peat.

She's talking about making layers of peat, water, peat, pile heavy stuff on top of it, etc., etc....

Someone else tells me nah, just soak the *vermiculite* before mixing everything and the peat will get moistened from that (but would that throw off the peat measurement?)...

So I thought I'd ask here. Anyone who uses peat in container mix, how do you moisten it?

When following a mix recipe with peat, how do you measure it (before or after moistening it and does that make a difference to your measurements)?

[luigiwu]

a lot of water is what it takes. If you bought your peat as a compressed bale, yup, just keep adding water and stir it up. I measure it dry.
If you don't have a cement mixer and need to mix a big batch, try putting it on a tarp and then picking up a corner and kicking the stuff towards the middle. repeat at each corner etc. hosing it down until its no longer dry

[hiker_]

Thanks!

When you mix your container mix, I hear you're supposed to moisten it and let it sit 1-2 weeks so the lime can activate and change the pH. Everyone, do you do that? Do you get away without doing that?

If you do wet it in advance, and you use a slow-release fertilizer, should you add it to the mix at the same time as the lime, and then let it sit for 1-2 weeks? Or would that cause the fertilizer to release while it sits and then burn the plants when you pot them into the mix?

[luigiwu]

I make my potting mix with the lime mixed in and premoisted. When I plant, I add a ring of 10-10-10. That's it. No waiting around and letting the mix 'stew.'

[hiker_]

That's a relief to hear! In that case, I'll probably just mix it dry tomorrow (because that's when I have time to) and moisten it...just before potting up? Is that when you wet it? The same day, or a day before, or...what do you mean by "premoistened"?

Thanks!

[luigiwu]

premoisten means my whole potting mix is already hydrated (water added) before I fill my containers.
I measure out all the ingredients (with the exception of fertilizer) and I add water. The damp/premoistened mix is ready for containers at that point.

[hiker_]

Thanks! Let me see if I understand you. This is what you do?

1. Mix all ingredients except fertilizer.
2. Add water.
3. Put into containers the same day.
4. Top dress with fertilizer, also the same day.
5. Pot up, also the same day.

OK...I hope it'll work just as well if I mix it dry and just leave it dry for 1-2 weeks until I'm about to pot up. Keeping it dry should prevent mold...I hope (it's been pretty humid here). Thanks for being so patient with me!

[luigiwu]

pretty much, except putting a ring of fertilizer is the very very last thing I do - are you familiar with Earthboxes and its methodologies?
I think its fine to leave your diy potting mix dry but honestly, I don't think you really have to worry about 'mold' even if you moistened the mix beforehand... peat holds water for a long long time. Plus this mix will be sitting out in the rain etc!
Again, I've mentioned this before but you'll be surprised at how much water it takes to wet compressed peat!

[hiker_]

EarthBoxes, that does clarify, thanks!

I'm worrying because I got hairy white mold growing on the mix that my neighbor gave me. Which was the above recipe and she had premoistened it. But...I had added a little Bio-Tone and stored it in two 5 gallon paint buckets. So it was sealed and the mold had food. I'm kicking myself now.

I was planning on stacking the containers in the garage so they'd be out of the rain till I needed them. Maybe instead I should leave them out in the rain so they get some wetting! I think my real problem before was adding the fertilizer and leaving it sealed.

Anyway, thanks again!

[fonseca]

Bio-tone contains Mycorrhizae, so I would consider white mold a good sign. How does it smell? I know my soilless mix has finished "cooking" when I see lots fungal activity. I inoculate with Mycogrow Soluble and let it sit for around three weeks.

When using organic fertilizer like Bio-tone, which has a substantial amount of high-nitrogen feather meal in it, you should let the mix rest for at least a few days. If you plant in it immediately after mixing, you may experience nutrient burn firsthand when using Bio-tone at the recommended rate.

More importantly, you want to give the microbiology time to get established, and the lime time to raise the PH. IME this can help prevent issues like nutrient lockout and burn. My container mix is rather hot, since my goal is not to add fertilizer for the rest of the season.

I like to amend sphagnum peat with dolomite lime, and then moisten separately from the rest of the ingredients. I use a surfactant as well, as peat can be extremely hydrophobic when completely dry. Since your recipe is for parts, pre-wetting the peat will increase its volume and affect your ingredient ratio, so I would measure it dry.

I then combine all ingredients in a giant pile on a tarp, and water with fresh vermicompost tea. I'll turn it the next day and water in more tea if it's too dry.

I think your recipe will be effective for container growing. You might consider replacing three gallons of peat with two gallons of quality mushroom compost and one gallon worm castings. That would put you at 5% castings in the final mix, which is a good place to be. I personally use a lot more compost as a percentage, but this is a safe amount to add to your recipe, without readjusting the ratios of other ingredients.

Pictured below are mycelia in one of my soil batches. The visible ingredients include biochar, coir husk chips, medium vermiculite, and coir fiber. Not visible is composted cow, horse and chicken manure, along with mushroom compost, worm castings and a base of sphagnum peat and coir pith, plus a host of amendments. It's easy to get carried away.

I love growing organically in containers. It has its challenges, but the reward is delicious.