Questions about soilless mix

[DurbanDan]

Hi everyone,

I recently acquired some pro-mix potting mix and used it to pot up some seedlings. It consists of about 85% peat moss, and 15% perlite. It comes amended with a wetting agent as well as lime to balance pH, but I have not checked it for myself. When I potted my plants I increased the ratio of perlite:mix to about 1:3. I also picked up some Neptune's Harvest organic fish and seaweed ferts (2-3-1).



Has anyone had experience with this medium? and if so what kind of watering/feeding schedule should I be aiming for so that I don't end up with root rot or nute burn? Should I spend the cash on decent pH meter to make sure the peat moss doesn't become too acidic?

any feedback would be greatly appreciated...

 

[Droopy Dog]

You will need to add more lime. Just like the perlite, the promix doesn't have enough in there. Powdered dolomite lime, ~1tbl/gallon of mix.

Yes, spend the money on a decent pH meter and calibration solutions. It will save you all sorts of aggravation and is money well spent.

DD

 

[DurbanDan]

Thanks for the feedback DD.


I just went and picked up a nice pH kit from my old science teacher. He said I can borrow it for as long as I like and than any time in the future so.. score! More money stays in my pocket.

I'm going to check my pots tonight and see if I need to get some more lime yet. I've read that the sphagnum moss will make increasingly acidic as it is broken down by microbial action. All my babies look to be flourishing so far but I'll definitely play it safe and keep some lime on hand when I transplant them to their final containers.

I've been just hand watering (with rain water) every 2-3 of days when the medium starts getting dry. I guess I've been treating it like a typical soil grow. Its amazing how much water the stuff will hold. I think I was probably overwatering for the first couple of weeks.. trying to get some run off during waterings. I've backed off since to avoid root rot and/or locking out oxygen.

I haven't introduced any ferts yet but I will probably do so gently at about 1/4 strength. If they look happy I'll water the ferts into them once every week and up the doses as I go. The pro-mix doesn't look very nutrient rich but I am hesitant to run nutes every time I water as if it were a hydro setup. I just don't know if its really necessary?

 

[Droopy Dog]

Get the powdered dolomite lime and extra perlite on hand now. Mix it into the promix dry. Put it into a waterproof container/bucket/whatever and add water till the mix is saturated, but not floating. LOL

Dry peat moss is very hard to get wet the first time and it's best to have the lime get wet and interact with it before use. Lime is not like a nute that you add whenever, but needs to be there from the get go. It is just very finely ground rock and a slow release.

I usually add the perlite and lime and whatever other meals are going in, wet it down and let it sit for several days or more before use.

I also always water to run off, ~30%+-. This will avoid any salt build ups and if you don't over nute, any need to flush.

DD