Comparison: Best Costco Potting Soil Mix (Updated | Nov 11th)
We’ve dug into the dirt (literally) to compare the top potting soil mixes available at Costco, weighing quality, value, and real garden results. Whether you’re repotting houseplants or starting a summer veggie garden, let us help you pick the perfect mix without the guesswork.
- Best for peat-free organic: Back to the Roots 100% Organic Potting Mix (Value 12 Quart) | Premium Blend | Made in The USA
- Best for 6-month feed: Miracle-Gro Potting Mix
- Best for gnat-resistant indoor: Miracle-Gro Houseplant Potting Mix: Fertilized
- Best for organic outdoor feed: Miracle-Gro Organic Outdoor Potting Mix
- Best for moisture-control mix: Miracle-Gro Moisture Control Potting Mix
- Best for all-purpose growth: Miracle-Gro Potting Mix
- Best for coconut coir indoor: Miracle-Gro Indoor Potting Mix
- Best for balanced water indoor: Miracle-Gro Organic Indoor Potting Mix
- Best for mycorrhizae indoor mix: Back to the Roots 100% Organic Indoor Potting Mix (Value 12 Quart) | Promotes Healthy Houseplant Growth| Made in The USA
- Best for fast root starter: Miracle-Gro Seed Starting Potting Mix
Product Comparison: Best Costco Potting Soil Mix
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.
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 Houseplant Potting Mix: Fertilized, Perlite Soil for Indoor Gardening, Designed to Be Less Prone to Gnats, 4 qt.
- Growing indoors is easy under the right conditions; Miracle-Gro Houseplant Potting Mix combines key elements plants need to thrive
- Recommended for growing beautiful indoor houseplant varieties like Pothos, Spider Plants, Monstera, Philodendron, English Ivy and more
- This indoor plant soil is less prone to gnats, thanks to the combination of perlite, sphagnum and peat moss that’s just right
- Certified by the Mulch & Soil Council as a quality product in compliance with industry standards
- A single 4-qt bag fills an 8-inch container; for even more spectacular results, start regular feedings with Miracle-Gro Plant Food 30 days after planting
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 Moisture Control Potting Mix, For Container Plants, Protects against Over- and Under-Watering, 8 qt., 2-Pack
- Miracle-Gro Moisture Control Potting Mix feeds plants for up to 6 months and Grows Plants Twice As Big! (vs unfed plants)
- This potting medium protects against over and under watering; also absorbs up to 33% more water than basic potting soil* with exclusive AquaCoir Formula (*soil that does not contain sphagnum peat moss, coir, and wetting agent)
- Use this gardening product with all types of container plants, including flowers, vegetables, annuals, perennials, and shrubs
- To use this potting soil, fill a container about 1/3 full with potting mix; place your plant in the pot and cover with more mix
- This bundle comes with two 8 qt. bags of Miracle-Gro Moisture Control Potting Mix; each fills two 8-inch containers (exact amounts may vary depending on the size of the root ball)
Miracle-Gro Potting Mix, For Indoor or Outdoor Potted Plants, Flowers, Vegetables, Shrubs, Annuals, and Perennials, Feeds Up to 6 Months, 8 qt.
- Feeds all potted plants: Miracle-Gro Potting Mix feeds all types of potted plants, including flowers, vegetables, shrubs, annuals, and perennials for up to 6 months
- Promotes growth: This potting soil Grows Plants Twice As Big! (vs. unfed plants)
- Boosts color: Get more blooms for more color (vs unfed plants)
- Application: To apply 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; water thoroughly
- Coverage: Each 8 qt. bag of Miracle-Gro Potting Mix fills two 8 inch containers (exact amounts may vary depending on the size of the root ball)
Miracle-Gro Indoor Potting Mix, Blended for a Variety of Houseplants, Feeds for up to 6 Months, 16 qt., 2-Pack
- Miracle-Gro Indoor Potting Mix feeds houseplants for up to 6 months and is designed to be less prone to gnats (contains no compost or bark, which are known to shelter fungus gnats)
- This potting mix contains coconut coir, which holds and releases water and helps soil re-wet
- Where to use: Blended for a wide variety of indoor container plants, including climbing, foliage, flowering, and tropical plants
- How to use: To use, fill a container about 1/3 full with potting mix; add more mix after placing your plant in the pot
- What’s included: This bundles includes two 16 qt. bags of Miracle-Gro Indoor Potting Mix, each able to fill one 12-inch containers (exact amount may vary based on the root ball size)
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)
Back to the Roots 100% Organic Indoor Potting Mix (Value 12 Quart) | Promotes Healthy Houseplant Growth| Made in The USA
- FORMULATED FOR INDOOR USE: Our Potting Mix contains organic yucca extract that aids in retaining moisture in the soil whichs keeps your indoor plants happy and healthy
- ROOT-BOOSTING MYCORRHIZAE: This beneficial soil component provides your plants with a natural, organic way to boost their root development and nutrient uptake
- ORGANIC AND PEAT-FREE: Our indoor potting mix helps reduce greenhouse emissions and environmental impact, making it a responsible choice for conscious consumers
- BALANCING DOLOMITIC LIMESTONE: Balances the alkalinity and acidity levels of the soil, which ensures that your plants receive the necessary nutrients from the potting mix to grow healthy and strong
- SAFE FOR PETS AND PEOPLE: Made without bark or compost, this potting mix is less prone to indoor gnats and pests, making it a worry-free option for your indoor gardening needs
Miracle-Gro Seed Starting Potting Mix, 8 Quarts (Pack of 2), For Use in Containers
- Specially formulated for fast root development
- Enriched with Miracle-Gro Plant Food
- Excellent for starting cuttings
- Use when starting from seed and with leaf, stem or root cuttings
- This bundle includes two 8 qt. bags of Miracle-Gro Seed Starting Potting Mix
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 look for when choosing a potting mix for indoor plants?
Focus on moisture retention, pH balance, and pest resistance. An organic mix with yucca extract or coconut coir helps keep soil evenly moist, while peat‑free formulas reduce the risk of fungus gnats. Also consider whether the mix includes built‑in fertilizer for longer feeding periods.
How does Back to the Roots 100% Organic Potting Mix compare to Miracle‑Gro Indoor Potting Mix?
Back to the Roots is peat‑free, uses upcycled plant material and yucca extract for moisture control, making it a more environmentally friendly option. Miracle‑Gro Indoor includes peat, perlite, and a quick‑release fertilizer that feeds plants for up to six months, which may produce faster growth but has a higher carbon footprint.
Is a fertilizer‑infused mix like Miracle‑Gro Moisture Control worth the extra cost?
Fertilizer‑infused mixes can boost growth and produce larger blooms, especially for heavy feeders like vegetables and flowering annuals. However, if you prefer to control nutrient levels yourself or use organic amendments, a plain organic mix such as the Back to the Roots or Miracle‑Gro Organic Outdoor may be more cost‑effective.
Which potting mix offers the best value for large container gardening?
Miracle‑Gro Moisture Control comes in a two‑bag 8‑qt bundle that feeds plants for up to six months and absorbs 33% more water, providing good value for big pots. For an organic alternative, the Miracle‑Gro Organic Outdoor 16‑qt bag also fills a 12‑inch container and includes a natural fertilizer, though it may need supplemental feeding later.
Can I use the same potting mix for both indoor and outdoor containers?
While many mixes work in both settings, indoor mixes like Back to the Roots Indoor Potting Mix are formulated without bark or compost to reduce gnats, making them ideal for houseplants. Outdoor mixes such as Miracle‑Gro Organic Outdoor contain peat and are designed for harsher temperature swings, so they generally perform better outside.
What are the benefits of a peat‑free potting mix?
Peat‑free mixes lower greenhouse‑gas emissions and often use renewable materials like wood fines or coconut coir, which improve sustainability. They also tend to have better aeration and drainage, reducing the risk of root rot in both indoor and outdoor containers.
How important is the added pH‑balancing component in a potting mix?
A balanced pH ensures nutrients are available to plant roots; mixes with dolomitic limestone, like Back to the Roots, help maintain a neutral to slightly alkaline environment. This is especially crucial for vegetables and herbs that are sensitive to acidic soils.
Should I consider a seed‑starting mix for my garden projects?
Seed‑starting mixes, such as Miracle‑Gro Seed Starting Potting Mix, are lightweight and sterile, promoting fast root development and reducing disease risk. They lack heavy fertilizers, so you’ll need to add a balanced feed once seedlings emerge, but they provide an excellent foundation for healthy growth.