Wednesday, March 16, 2011

Mixing Homemade Potting Soil

Seed starting is about to get underway again so I needed to mix up some potting soil. I used to just use pro-mix but it gets quite expensive once you start doing alot of potting. You are looking at saving about 50% when you mix your own. Here is my recipe:

Dan's Mix

3 parts peat moss
1 part compost
1/2 part vermiculite
1/4 part pearlite
2 cups dolamitic lime (based on a 23.75 gallon batch, adjust accordingly)

I measure all parts with a 5 gallon bucket, this simplifies the process. The real key to this mix is the dolamitic lime. Peat moss is acidic and the dolamitic lime gently neutralizes the acidity, making for happier seedlings & plants.

I start by screening the peat moss into a wheelbarrow and gradulaty add the dolamitic lime. With that done I screen the compost into the wheelbarrow. Screening is not imparative but it does remove alot of sticks and clumps that little seedlings don't like. Leaving the sticks in also robs the soil of nitrogen as they break down.

When the soil is prepared I then added the vermiculite & pearlite. Then everything is mixed thoroughly with a square shovel.

Here is the final product. It is airy, holds moisture well and should make for some happy plants.


  1. Great mix! If I had money to buy the add-in ingredients, I'd use this, but for now they get compost, sticks and all. Hehe, you may have seen how well that makes soil blocks though. And maybe when I build my chicken coop I'll make a screen like yours, but it'll use 1/4 inch holes, what's that about 1 cm, as that's what I'll use for my coop and expect to have some left over.

  2. Hey Rich, the screen is made with hardware cloth. I think the holes are about a 1/4". It just separates out all the big stuff. I have not tried the mix with soil blocks, I think it might be a little to loose to hold together.

  3. How great that you make your own!

  4. that is a good mix. Glad you pointed out the necessity of the lime with the peat. Most don't realize that. I do buy a generic of pro mix which is less expensive and it seems to work the same.

  5. That is a nice looking batch of potting soil! The savings sound significant enough to make the extra work worthwhile.

  6. That mix looks fabulous! We make our mix for pots too and the secret ingredient is our own humus :)
    Greetings from Uruguay!


  7. This is a great seed starting mix. I can't wait to see what you mix up for actual potting soil.

    I use:
    2 parts coco coir
    1 part perlite
    1 part compost
    Dolomite lime- 1 tablespoons per gallon or 1/2 cup per cubic foot

    This mix is fertilized with 1 tsp. blackstrap molasses and Jack's Classic dry fertilizer every other watering, and a touch of epsom salt when needed.

    It works great!

  8. We should do the same thing...have all the ingredients and it's cheaper.

  9. Great mix recipe. Your final product looks good.

  10. Dan, I have the same inquiry as red icculus. I'm starting a balcony garden (much like prue's) and I would like to know what kind of soil mix I should use. I got a LOT of bags of garden soil on sale, but I know I can't just put that in the boxes because it will pack down over time. Let me know! Maybe I can adjust your seed starting mix a bit with less coco coir (that's the medium I'm using).

  11. Kalena Michele - The recipe would work well in containers. You can also adjust the compost to coco coir ratio to 50/50 as well. You do want to make sure it stays light and drains well though or the plants will die.