Comparison: Best Organic Seed Starting Soil (Updated | Nov 11th)
Not just any mix will do—organic seed starting soil sets the foundation for strong roots, vibrant growth, and a thriving garden. But with so many options out there, how do you choose the best one? We’ve tested top contenders to help you find the perfect blend that’s nutrient-rich, easy to use, and truly organic—because your seeds deserve the best shot at life.
- Best for peat-free power: Back to the Roots 3-in-1 Seed Starting Mix 6 Quarts
- Best for expandable volume: Back to the Roots Organic Seed Starting
- Best for mycorrhizae boost: Espoma Organic Seed Starter Premium Potting Soil Mix – All Natural & Organic Seed Starting Mix with Mycorrhizae. For Organic Gardening
- Best for coconut coir: Burpee Organic Coconut Coir Concentrated Seed Starting Mix
- Best for peat classic: Jiffy Natural & Organic Seed Starting Soil Mix
- Best for nutrient pellets: WONDER SOIL | 100 Organic Seed Starter Pellets | Ready to Plant Seed Starting Soil Loaded with Pre-Mixed Nutrients | Fast Germination | Indoor or Outdoor | 100 Count
- Best for regenerative compost: Coast of Maine Organic & Natural Sprout Island Blend Seed Starter – Seed Germination & Root Plant Cuttings w/ Composted Manure
Product Comparison: Best Organic Seed Starting Soil
Back to the Roots 3-in-1 Seed Starting Mix 6 Quarts, 100% Organic & USA Made for Herbs, Veggies, Flowers, w/Nutrient Rich Plant Food, Worm-Castings, & Moisture Controlling Yucca Brown
- NUTRIENT-RICH, NATURAL, AND ORGANIC SOIL: Grow a bountiful garden in your home with the Back to the Roots All-Purpose Natural and Organic Peat-Free 3-in-1 Seed Starting Mix, packed with the nutrients needed for your plants, flowers, and vegetables to thrive
- MYCORRHIZAE, YUCCA EXTRACT, AND COCONUT COIR FOR STRONG ROOT DEVELOPMENT: This organic potting soil has mycorrhizae, coconut coir, and yucca extract which enhances the root’s uptake of water and the nutrients required by your plants for growth
- FEATURES pH BALANCING DOLOMITIC LIMESTONE: The dolomitic limestone of this potting soil has a combination of calcium carbonate and magnesium carbonate which effectively neutralizes acidity and prevent nutrient deficiency
- ZERO-RISK GARDENING AND GREAT FOR THE PLANET: Made in the USA and 100% guaranteed to grow; If you have any problems, we will send you a new bag to get you growing; Mined peatlands contribute yearly CO2 emissions equivalent to what cars all over the world are releasing — that’s why we think it’s so important to leave peat alone and offer the 1st premium, 100% peat-free soil in the market
- THE PERFECT GIFT: The perfect holiday gift, it comes in a beautiful packaging so that it’s ready to be given to foodie, garden-loving and eco-conscious friends and family; This kit is also part of our Grow One Give One campaign, simply share a picture on social media, tag us and use the campaign hashtag, and we’ll donate a kit to a classroom of your choice
Back to the Roots Organic Seed Starting, Compressed Block expands to 12 Quarts, Made for Herbs, Veggies, Flowers
- A balanced pH, which means it’s truly all-purpose. Use alone or as an amendment for anything in a pot or in the ground — vegetables, flowers, herbs, and even starting seeds.
- Expands to 12 Quarts
- Peat Free OMRI Listed, assuring organic production, handling, and processing
- 100% SATISFACTION GUARANTEE: If you are not satisfied or have any issues with this product, just shoot us a note and our dedicated customer support team will make sure we get you growing or send you a refund/replacement.
- GROWONEGIVEONE — Share a photo of your growing garden and we’ll donate a Kids Grow Kit and STEM elementary school curriculum to a classroom of your choice.
Espoma Organic Seed Starter Premium Potting Soil Mix – All Natural & Organic Seed Starting Mix with Mycorrhizae. For Organic Gardening, 16 qt, bag – Pack of One
- CONTAINS: This organic Seed Stating soil mix is a rich blend of sphagnum peat moss & perlite with yucca extract and lime to ensure correct pH.
- MYCO-TONE: A blend of endo & ecto mycorrhizae.
- WHEN TO USE: Use to germinate and start seeds. Great for flower, vegetable, herb & more plant types. Can also be used to root stem and leaf cuttings.
- PROMOTE ROOT GROWTH: Organic seed starter mix ensures ideal moisture retention and aeration.
- ORGANIC GARDENING: Contains a rich blend of only the finest natural ingredients. No synthetic plant foods or chemicals are used.
Burpee Organic Coconut Coir Concentrated Seed Starting Mix, 16 Quart
- ORGANIC COCONUT COIR: Made from recycled coconut husks, coir is a light, sustainable growing medium that holds the perfect amount of moisture for starting seeds. 100% biodegradable soil alternative. Environmentally-friendly and a renewable alternative to peat moss. OMRI listed and certified organic.
- IDEAL GROWING MIX: Improve seed germination and root growth with this premium coconut fiber mix, which improves nutrients absorption! Great for flower, vegetable, herb & more plant types. OMRI listed. Naturally disease and pathogen resistant, it will help you grow healthy live plants.
- EASY TO STORE & EXPAND: Each compact coconut coir brick expands into 8 quarts of seed starting mix, providing 16 quarts total. Just add water to expand! Dehydrated bricks save space until planting. Once expanded, coconut coir provides a quality growing medium for all types of plants – indoor plants, house plants, outdoor plants, and more!
- NATURALLY CONSERVES WATER: Renewable coco coir has excellent moisture retention and better air circulation than peat. This eco-friendly, premium seeds starting mix combines well with other potting soil and compost for container plants & raised beds.
- 100% GUARANTEED: Burpee is committed to the success of all gardeners. We treat each order with care to ensure healthy seeds, plants, soil mixes & gardening supplies are sent in excellent condition. If you are unsatisfied with your purchase, we aim to make it right!
Jiffy Natural & Organic Seed Starting Soil Mix, 10 QT (2 Bags (20 QT)
- This Jiffy Seed Starting Mix Includes: peat moss, vermiculite and lime.
- Peat Moss: Peat can hop up to 20x it’s weight in water, provides aeration for plant roots and helps retain nutrients plants need.
- Vermiculite: Prevents soil compaction, retains moisture and improves aeration. Can soak up to 3-4x it’s volume in water!
- Lime: Promotes a healthy PH balance in soil.
WONDER SOIL | 100 Organic Seed Starter Pellets | Ready to Plant Seed Starting Soil Loaded with Pre-Mixed Nutrients | Fast Germination | Indoor or Outdoor | 100 Count
- ORGANIC SEED STARTING PELLETS: We are the ONLY Organic Coco Coir that contains enhanced nutrients. Ours coconut coir includes worm castings, mycorrhizae, kelp, and more to encourage faster germination & healthier growth! Feeds your plants for up to four months!
- LOADED WITH PRE-MIXED NUTRIENTS FOR FASTER GERMINATION! Wonder Soil Pellets are loaded with nutrients for faster germination. Pellets include worm castings, mycorrhizae, kelp, calcium and organic nutrients.
- ADD WATER & WATCH IT GROW! Add water and watch Wonder Soil expand and grow to 4 times its original size leaving you with nutrient rich coco coir seed starting soil mix.
- PERFECT FOR ALL INDOOR/OUTDOOR SEEDING APPLICATIONS: Our seed starter pellets are the perfect choice for all seed starting applications both indoor or outdoor.
- USED BY PROFESSIONAL GROWERS & NURSERIES: Used by professional growers, nurseries and experienced gardeners globally.
Coast of Maine Organic & Natural Sprout Island Blend Seed Starter – Seed Germination & Root Plant Cuttings w/ Composted Manure, Mycorrhizae, Worm Castings & Kelp – Enhanced Drainage (8 Qt)
- PREMIUM INGREDIENTS: This specifically crafted organic compost blend for seed germination and rooting cuttings is carefully formulated to provide essential nutrients that supports seedling development, drainage and aeration.
- READY TO USE SEEDLING SOIL: Coast of Maine Organic Seed Starting Mix is ready to use in cell packs, trays or flats. This nutrient starter charge includes mycorrhizae, worm castings, kelp & fully cured compost for healthy growing plants.
- EARTH FRIENDLY COMPOST FOR SOIL: OMRI listed for organic use, our organic potting soil for annuals reflects Coast of Maine’s commitment to nature-conscious, responsible gardening practices.
- HARVESTING A BRIGHTER FUTURE: Since 1996, Coast of Maine has been dedicated to sustainable, regenerative practices that nourish healthy plants. Our indoor and outdoor gardening products are made with all-natural components, providing a sustainable, planet-friendly solution for enriching garden soil. Our commitment to quality and environmental stewardship ensures that every product supports a healthier garden and planet.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
Buying Guide
FAQs
What key factors should I consider when picking an organic seed starting mix?
Look for a balanced pH, presence of mycorrhizae or kelp for root development, and a sustainable base such as peat‑free coconut coir or compost. Moisture retention and aeration are critical, so ingredients like perlite, vermiculite, or coconut coir are valuable. Finally, check for certifications (OMRI listed) and any added nutrients that can speed germination.
How does a peat‑free mix compare to a traditional peat‑based mix?
Peat‑free mixes, like those using coconut coir, provide similar water‑holding capacity while offering better aeration and a renewable source, reducing environmental impact. Traditional peat mixes often have excellent moisture retention but can be acidic and are harvested from sensitive peatlands. For eco‑conscious gardeners, peat‑free options usually deliver comparable germination rates with a smaller carbon footprint.
Which product gives the best value for larger gardening projects?
The Back to the Roots 3‑in‑1 Seed Starting Mix expands to 6 quarts, while the compressed block version grows to 12 quarts, effectively doubling the volume for a similar price point. Burpee’s coconut coir brick expands to 16 quarts, offering the most bulk per unit but requires water activation. If you need the highest quantity per dollar, the expanded 12‑quart block or the 16‑quart coir brick are typically the most cost‑effective choices.
What advantages do added mycorrhizae and kelp provide in seed starters?
Mycorrhizae form a symbiotic relationship with plant roots, improving nutrient and water uptake, which leads to stronger seedlings. Kelp contributes natural hormones and micronutrients that stimulate germination and early growth. Together they create a more resilient start, especially in indoor or low‑light conditions.
How do expansion bricks affect storage and convenience?
Compressed bricks, such as Burpee’s coconut coir or Wonder Soil pellets, stay compact and dry until you add water, saving space in cabinets and reducing shipping weight. Once hydrated, they expand into a ready‑to‑use mix, eliminating the need to pre‑mix large bags. This format is especially handy for gardeners with limited storage or who prefer to prepare only the amount they need.
Is a compressed block that expands to 12 quarts better than a pre‑mixed 6‑quart bag?
A compressed block offers more flexibility because you can expand only the quantity you require, reducing waste and often lowering the cost per quart. Pre‑mixed bags provide immediate use without the extra step of adding water, which can be preferable for quick projects. Choose the block if you value volume and storage efficiency; choose the bag for convenience and instant readiness.
Why is pH balancing important in seed starting mixes?
A neutral to slightly acidic pH ensures nutrients remain soluble and accessible to young roots, preventing deficiencies. Products like Back to the Roots include dolomitic limestone, while Jiffy adds lime to stabilize pH and counteract acidity from peat or coir. Maintaining proper pH reduces the need for later soil amendments and promotes uniform germination.
Which mix is most suitable for indoor seed trays and starter kits?
Jiffy Natural & Organic Seed Starting Soil Mix is formulated for small containers, offering a lightweight blend of peat moss, vermiculite, and lime that provides excellent moisture control. Back to the Roots 3‑in‑1 also works well indoors, with added coconut coir and yucca extract for stronger root systems. For the most sustainable indoor option, consider the peat‑free coconut coir bricks from Burpee or Wonder Soil, which expand to a fluffy, well‑draining medium.