PRO-MIX 16 qt. Bag Premium Organic Seed Starting Mix

PRO-MIX 16 qt. Bag Premium Organic Seed Starting Mix


$21.99 Regular price
  • In stock - departs in 2-3 business days

This bulk seed starting mix is an all-purpose potting soil for professional and hobby growers everywhere. Use peat-basted seed starter soil to kick-start produce, herbs, flowers, cuttings…you name it! It's particularly effective for starting perennial flowers and shrubs indoors before transplanting them outside.

PRO-MIX Organic Seed Starting Mix has a 6-1-2 NPK ratio, which is ideal for green, leafy growth and also makes a good fertilizer. MYCOACTIVE technology produces stronger roots to help plants resist transplant shock and general stress - and spur them to grow up to 20% larger than standard seed starting soil. The coco fiber maintains good moisture levels to prevent rotting.

A single application of PRO-MIX seedling starting soil will feed your plants for up to three months, offering the sustained nutrients they need at this early stage. It's OMRI-listed for organic gardens and requires no additional mixing or preparation. Greenhouse Megastore sells PRO-MIX seed starting mix in bulk for high-volume growers and has free shipping on qualifying orders.

PRO-MIX Seed Starter Organic Mix Features:

  • Formulated with quality all-natural horticultural ingredients for growing a wide range of plant species.
  • Contains MYCOACTIVE technology with Mycorrhizae, an exclusive biological growth enhancer that promotes plant growth, root strength and stress resistance for increased yields.
  • Provides easier plant care than standard mixes and results in improved seedling performance.
  • Organic fertilizer that gradually feeds plants for up to three months.
  • 16-quart loose fill bag
  • NPK: 30-5-10
  • OMRI-listed


  • Canadian sphagnum peat moss
  • Coir (coco fiber)
  • Perlite
  • Limestone
  • Organic fertilizer
  • Mycorrhizae - PTB297 Technology

Additional Information

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Customer Reviews

Based on 34 reviews
John Bhend (Harrisville, US)
excellent seed starter

I use this mix exclusively to start all of our seed, second year. Germinations were fast and 99% of our seeds grew!

Shawn Morse (Charlotte, US)
Great results!

The best seed starting mix out there!

Karolee Withers (Big Lake, US)
Great seed starter

We used this mix exclusively to start all of our seed. Germinations was fast and 99% of our seeds grew!

C.G. (Coeur d'Alene, US)
Overall good, but still has sticks and twigs

Pro-Mix Premium Organic Seed Starting Mix is largely a very nice quality fine-grained mix, HOWEVER there was more than 1 cup of large sticks and twigs in the mix/bag. I picked them out by hand.

Legacy Review

The Pro-Mix Premium Organic "Seed Starting" mix I got was really just potting mix. It had large chunks of bark, twigs and chips of wood products. Something must have gone wrong with the screening process when this was getting mixed and bagged. I did send Greenhouse Megastore a picture and they made it right with me.. Great service.. poor product on this bag . I have purchased a lot of Pro-Mix garden products and this purchase was the only one that didn't meet my expectations. Seed starter mix should not be "chunky".

Legacy Review
Pro-Mix Premium Organic Seed Starting Mix

Always have a good result with this product. It does a good job feeding my seedlings for a couple of months until I put them into the ground. It has higher amounts of N-P-K than other similar products that are more available at local hardware stores, garden centers, etc.

Legacy Review
Very disappointed this year

I have been using this mix for the past few years. This year, I was only able to buy it at Greenhouse Megastore for TWICE the price I usually pay. I was very disappointed with the quality...a lot of peat clumps, sticks and twigs this year. I sifted them out. After a few weeks I had tons of grass growing in the mix. What the heck happened with this "used to be" fine seed starting mix Pro-Mix? Won't buy again

Herb Winter
Rough starter

Had to pick out a lot of hard sticks and quite a few rocks. I expected a seed starting mix to be much more refined.

Legacy Review
The Best Seed Starting Mix

Over the years, I have tried a lot of different seed starting mixes, but I have found Pro-Mix Premium Organic Seed Starting Mix is the best I have ever used. The Mycorrhizae, their exclusive biological growth enhancer, promotes excellent growth and root formation. I will use no other.

Legacy Review
Infested with fungus

I ordered two bags and liked it while using the first one. Then I opened another bag and found all media surface was covered with yellow grains' fungus with a strong smell of fungus. Tossed the whole bag. What a waste!