Comparison: Best Costco Miracle Gro Organic Potting Soil (Updated | Nov 11th)
If you’ve ever stood in the gardening aisle wondering which potting soil truly earns its stripes, you’re not alone. At Costco, the hunt for the best value meets quality—especially when it comes to Miracle-Gro’s organic options. But does the bulk buy live up to the hype? Spoiler: not all bags are created equal.
- Best for quick-release feed: Miracle-Gro Organic Outdoor Potting Mix
- Best for balanced moisture: Miracle-Gro Organic Indoor Potting Mix
- Best for large outdoor pack: Miracle-Gro Organic Outdoor Potting Mix
- Best for outdoor bundle: Miracle-Gro Organic Outdoor Potting Mix
- Best for indoor bundle: Miracle-Gro Organic Indoor Potting Mix
- Best for mini indoor bundle: Miracle-Gro Organic Indoor Potting Mix
- Best for organic bounty: Miracle-Gro Performance Organics All Purpose Container Mix with Natural and Organic Ingredients
- Best for six-month feed: Miracle-Gro Potting Mix
- Best for vibrant six-month: Miracle-Gro 2 Pack Potting Soil Mix for Container Plants
- Best for peat-free premium: Back to the Roots 100% Organic Potting Mix (Value 12 Quart) | Premium Blend | Made in The USA
Product Comparison: Best Costco Miracle Gro Organic Potting Soil
Miracle-Gro Organic Outdoor Potting Mix, for Outdoor Container Plants, Contains Quick-Release Natural Fertilizer, OMRI Listed, 16 qt.
- Miracle-Gro Organic Outdoor Potting Mix contains a quick-release natural fertilizer and also feeds plants for up to 2 months
- This potting mix is made with responsibly sourced peat (one hundred percent of peat sourced from certified producers)
- Use this organic potting mix with all types of outdoor container plants, including flowers, vegetables, herbs, annuals, and perennials
- To plant in pots, fill the container partially full with potting mix, place the plant in the pot after loosening the root ball, cover with more mix and water thoroughly
- One 16 qt. bag of Miracle-Gro Organic Outdoor Potting Mix fills one 12-inch container (amounts may vary based on the size of the root ball)
Miracle-Gro Organic Indoor Potting Mix, Protects Against Over and Under Watering, for Indoor Container Plants, Houseplants and Starter Plants, OMRI Listed, 16 qt.
- Miracle-Gro Organic Indoor Potting Mix protects indoor plants against over and under watering
- This organic container mix is made with responsibly sourced sphagnum peat moss (one hundred percent of peat sourced from certified producers), coir, and quick-start natural fertilizer
- Use this potting medium with all types of indoor container plants, including houseplants and herbs; also great for seed starting
- To plant seeds, fill container with potting mix, follow seed package planting directions, and water; To use with transplants, partially fill container, place plant after loosening the root ball, cover with more mix pressing lightly, and water
- One 16 qt. bag of Miracle-Gro Organic Indoor Potting Mix fills one 12-inch container (amounts may vary based on the size of the root ball)
Miracle-Gro Organic Outdoor Potting Mix, for Outdoor Container Plants, Contains Quick-Release Natural Fertilizer, OMRI Listed, 25 qt.
- Miracle-Gro Organic Outdoor Potting Mix contains a quick-release natural fertilizer and also feeds plants for up to 2 months
- This potting mix is made with responsibly sourced peat (one hundred percent of peat sourced from certified producers)
- Use this organic potting mix with all types of outdoor container plants, including flowers, vegetables, herbs, annuals, and perennials
- To plant in pots, fill the container partially full with potting mix, place the plant in the pot after loosening the root ball, cover with more mix and water thoroughly
- One 25 qt. bag of Miracle-Gro Organic Outdoor Potting Mix fills three 10-inch containers (amount may vary based on the size of the root ball)
Miracle-Gro Organic Outdoor Potting Mix, for Outdoor Container Plants, Contains Quick-Release Natural Fertilizer, OMRI Listed, 16 qt., 2-Pack
- Miracle-Gro Organic Outdoor Potting Mix contains a quick-release natural fertilizer and also feeds plants for up to 2 months
- This potting mix is made with responsibly sourced peat (one hundred percent of peat sourced from certified producers)
- Use this organic potting mix with all types of outdoor container plants, including flowers, vegetables, herbs, annuals, and perennials
- To plant in pots, fill the container partially full with potting mix, place the plant in the pot after loosening the root ball, cover with more mix and water thoroughly
- This bundle includes two 16 qt. bags of Miracle-Gro Organic Outdoor Potting Mix; each fills one 12-inch container (amounts may vary based on the size of the root ball)
Miracle-Gro Organic Indoor Potting Mix, Protects Against Over and Under Watering, for Indoor Container Plants, Houseplants and Starter Plants, OMRI Listed, 16 qt., 2-Pack
- Miracle-Gro Organic Indoor Potting Mix protects indoor plants against over and under watering
- This organic container mix is made with responsibly sourced sphagnum peat moss (one hundred percent of peat sourced from certified producers), coir, and quick-start natural fertilizer
- Use this potting medium with all types of indoor container plants, including houseplants and herbs; also great for seed starting
- To plant seeds, fill container with potting mix, follow seed package planting directions, and water; To use with transplants, partially fill container, place plant after loosening the root ball, cover with more mix pressing lightly, and water
- This bundle includes two 16 qt. bags of Miracle-Gro Organic Indoor Potting Mix; each bag fills one 12-inch container (amounts may vary based on the size of the root ball)
Miracle-Gro Organic Indoor Potting Mix, Protects Against Over and Under Watering, for Indoor Container Plants, Houseplants and Starter Plants, OMRI Listed, 8 qt., 2-Pack
- Miracle-Gro Organic Indoor Potting Mix protects indoor plants against over and under watering
- This organic container mix is made with responsibly sourced sphagnum peat moss (one hundred percent of peat sourced from certified producers), coir, and quick-start natural fertilizer
- Use this potting medium with all types of indoor container plants, including houseplants and herbs; also great for seed starting
- To plant seeds, fill container with potting mix, follow seed package planting directions, and water; To use with transplants, partially fill container, place plant after loosening the root ball, cover with more mix pressing lightly, and water
- This bundle includes two 8 qt. bags of Miracle-Gro Organic Indoor Potting Mix; each bag fills two 8-inch containers (amounts may vary based on the size of the root ball)
Miracle-Gro Performance Organics All Purpose Container Mix with Natural and Organic Ingredients, Feeds Container Grown Vegetables, Flowers and Herbs for up to 3 Months, 1 cu. ft.
- Organic Goodness: Grow vibrant flowers, herbs, and veggies with Miracle-Gro Performance Organics All Purpose Container Mix made with organic and natural ingredients, like aged compost, for the spectacular results you expect
- Bountiful Harvests: Get twice the bounty versus unfed plants for more container-grown vegetables, flowers, and herbs
- How to Use: Perfect for all your indoor and outdoor container gardening, simply fill your favorite pots with this potting soil and watch your flowers, vegetables, and herbs thrive
- Nourish: This premium organic container soil provides continuous plant nutrition for up to 3 months, helping your potted plants flourish
- Trusted Results: Grow confidently with this OMRI Listed container mix that gives you the Miracle-Gro results you love with the organic and natural ingredients you want
Miracle-Gro Potting Mix, For Container Plants, Flowers, Vegetables, Annuals, Perennials, Shrubs, Feeds for up to 6 Months, 16. qt., 2-Pack
- Miracle-Gro Potting Mix feeds container plants for up to 6 months so you get more blooms for more color (vs. unfed plants)
- How to use: To use this potting medium, fill a container about 1/3 full with potting mix, place your plant in the soil, and fill the rest of the pot, pressing lightly
- What’s included: This bundles includes two 16 qt. bags of Miracle-Gro Potting Mix, each able to fill one 12-inch container (exact amounts may vary based on root ball size)
- Where to Use: Use this home gardening product with all types of container plants, including annual and perennial flowers, vegetables, herbs and shrubs
- This potting soil mix Grows Plants Twice As Big (vs. unfed plants)
Miracle-Gro 2 Pack Potting Soil Mix for Container Plants, Flowers, Vegetables, Shrubs, Annuals, and Perennials, Feeds for Up to 6 Months, 2 Cu Ft
- BIGGER PLANTS: Watch your container plants flourish with this potting soil that feed for up to 6 months to grow plants twice as big versus unfed plants
- VIBRANT COLORS: Get ready for a spectacular show of more blooms for more color versus unfed plants transforming your containers into dazzling displays
- WHERE TO USE: Perfect for all indoor or outdoor grown containers plants, including flowers, vegetables, herbs, and houseplants
- HOW TO USE: Pick a pot with drainage, fill it 1/3 full with this ready-to-use container mix, add your plant and fill in with more soil, then water; it’s that easy to create beautiful container gardens
- COVERAGE: Each 2 cu. ft. bag of Miracle-Gro Potting Mix fills two 14-inch containers (actual amount may vary depending on the size of the root ball)
Back to the Roots 100% Organic Potting Mix (Value 12 Quart) | Premium Blend | Made in The USA
- 100% Organic and Peat-Free: Our potting mix is 100% organic and peat-free—made from upcycled plant matter and wood fines from across the U.S. No imported peat, just better soil with a lighter carbon footprint.
- All-Purpose: Our premium potting mix is versatile and well-suited for herbs, veggies, fruits, and flowers. It caters to all your gardening needs, and is proudly made in the USA.
- Better Moisture Control and pH Balance: Our premium soil blend incorporates yucca extract for moisture control and dolomitic limestone for pH balancing.
- 100% Satisfaction Guarantee: Not satisfied? Let us know. Our support team will get you growing with a replacement or refund—no questions asked.
- 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.
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 should I consider when choosing between organic indoor and outdoor potting mixes?
Look at where you’ll be planting – indoor mixes are formulated to prevent over‑ and under‑watering, while outdoor mixes include a quick‑release natural fertilizer for tougher conditions. Check the ingredients: indoor blends often use sphagnum peat moss and coir, whereas outdoor blends rely on responsibly sourced peat. Also consider container size and how long you want the nutrients to last, typically two months for outdoor and up to three months for some all‑purpose mixes.
How do the 16‑qt and larger bag options compare in value?
Larger bags, like the 25‑qt outdoor mix, generally offer a lower cost per quart and can fill multiple containers, making them ideal for bigger projects. Smaller 16‑qt bags are convenient for occasional gardeners or for trying a product before committing. Bundles that include two 16‑qt bags often provide a modest discount compared to buying single bags, while still offering flexibility.
Is there a noticeable performance difference between Miracle‑Gro’s organic mixes and the Back to the Roots blend?
Miracle‑Gro’s organic mixes include a quick‑release natural fertilizer that feeds plants for up to two or three months, which can produce faster growth and larger blooms. Back to the Roots offers a peat‑free, 100% organic blend focused on sustainability and balanced moisture, but it doesn’t contain added fertilizer, so you may need supplemental feeding. Choose Miracle‑Gro for immediate nutrient boost, or Back to the Roots if you prioritize eco‑friendly ingredients.
Can I use the same potting mix for seed starting and mature plants?
Yes, both the indoor and outdoor organic mixes are suitable for seed starting because they provide a light, well‑draining medium. For mature plants, the added natural fertilizer in Miracle‑Gro mixes supports continued growth, while the Back to the Roots mix works well with regular feeding. Always follow the seed packet’s planting depth and water requirements for best results.
What are the key features that make the indoor mixes protect against over‑ and under‑watering?
The indoor mixes contain a blend of sphagnum peat moss and coir that regulates moisture retention, helping prevent waterlogged roots or rapid drying. They also include a quick‑start natural fertilizer that releases nutrients steadily, reducing the need for frequent watering. This balanced composition is ideal for houseplants that are more sensitive to moisture fluctuations.
How many containers can I expect to fill with each product size?
A 16‑qt bag of either indoor or outdoor mix typically fills one 12‑inch pot, though actual amounts may vary with root ball size. The 25‑qt outdoor bag can fill about three 10‑inch containers, while the 2‑pack 16‑qt bundles cover two 12‑inch pots. The Back to the Roots 12‑qt bag is designed for general use and can fill several smaller containers, depending on plant size.
Is there a noticeable price advantage to buying bundled packs versus single bags?
Bundled packs, such as the two‑bag indoor or outdoor mixes, often provide a slight discount compared to purchasing individual bags, making them a cost‑effective choice for gardeners needing multiple containers. Additionally, larger volume bags reduce packaging waste and lower the per‑quart price. However, if you only need a small amount, a single bag may be more economical to avoid excess product.