Compost blocks are sold at garden centers, home improvement stores, and online retailers

Compost blocks — also called coco coir bricks or compressed coconut husk — are stocked at most places that sell gardening supplies. Home Depot and Lowe's carry them in their garden sections, usually near potting soil and mulch. Local independent garden centers often stock them year-round, and some nurseries will special-order if they don't have them in stock. Online, Amazon, Wayfair, and specialty gardening sites like Johnny's Selected Seeds ship them, though shipping costs can be high because blocks are heavy.

Prices vary by brand, size, and where you buy. A single block typically costs between $3 and $8, depending on whether it's a small 5-liter brick or a larger 10-liter one. Buying in bulk — packs of 5 or 10 blocks — usually brings the per-block price down. Local pickup from a garden center often costs less than shipping, so it's worth calling ahead to check what's in stock before you drive.

Key Takeaways

  • Home Depot, Lowe's, and local garden centers stock compost blocks in their gardening sections, usually year-round.
  • Online retailers like Amazon and specialty gardening sites ship blocks, but shipping costs are significant because of weight.
  • Prices range from $3 to $8 per block depending on size and brand, with bulk purchases offering lower per-block cost.
  • Calling ahead to confirm stock saves a trip, especially for larger orders or specific brands.
  • Some garden centers will special-order blocks if they don't have them on hand.

What to look for when choosing a brand

Not all compost blocks are identical. Some are pure coconut coir, while others are blended with peat moss, perlite, or other amendments. Read the package label to see what's actually inside — if you're using the block for seed starting, you may want one with perlite already mixed in. If you're using it as a soil amendment for containers or raised beds, pure coir works fine.

Check the expansion ratio on the package. Most blocks expand to 2 to 3 times their compressed size when you add water, but some brands expand more or less. This matters if you're calculating how much finished soil you'll end up with. Brands like Coco for Cannabis, Jiffy, and Espoma are widely available and consistent, but store brands from Home Depot and Lowe's work just as well and cost less.

Buying in person versus ordering online

Buying in person lets you inspect the block for damage and avoid shipping fees. A single block weighs 1 to 2 pounds when compressed, but a pallet of 50 can weigh over 100 pounds, so shipping costs add up fast. If you need only one or two blocks, a local garden center is usually your cheapest option.

Online ordering makes sense if your local stores don't stock the brand you want, or if you're buying in bulk and the retailer offers free shipping on large orders. Amazon Prime can deliver blocks quickly in some areas, though you'll pay more per block than you would at a garden center. Compare the total cost — block price plus shipping — before you order.

Seasonal availability and stock issues

Compost blocks are most readily available in spring and early summer when gardeners are starting seeds and planting containers. Fall and winter stock thins out, though most big-box stores keep some on hand year-round. If you're planning a large project in winter, order early or call ahead to confirm availability.

Supply chain delays have affected some retailers, so if a store's website says a block is in stock, call before you go. Garden centers sometimes run out of popular brands mid-season, especially during spring planting rush. Smaller independent nurseries may have less selection but can often order what you need within a week.

Bulk purchasing and wholesale options

If you're buying 20 or more blocks, wholesale suppliers and agricultural co-ops sometimes offer better pricing than retail. Landscape supply companies often sell to homeowners and will quote bulk orders. Some online retailers offer tiered pricing — buy 10 blocks and get a discount, buy 25 and get a steeper one.

Costco and Sam's Club occasionally stock compost blocks in their seasonal gardening sections, usually at a lower per-block price than retail. Membership is required, but if you're a member and need a large quantity, it's worth checking what they have in stock during spring and summer.

Storage and shelf life

Compost blocks keep indefinitely if stored dry. Once you open a block and hydrate it, use the finished coir within a few weeks for best results — it can develop mold or odor if it sits wet for months. Store unopened blocks in a cool, dry place away from direct sunlight. A garage, shed, or basement works fine.

If you buy blocks in bulk and won't use them when ready, keep them in their original packaging or in a sealed container. Moisture and pests are the main concerns, so avoid damp basements or outdoor storage where rain can reach them.

Frequently Asked Questions

Can I buy compost blocks at grocery stores or big-box retailers other than Home Depot?

Some Walmart locations stock compost blocks in their garden sections, though selection is usually smaller than at Home Depot or Lowe's. Costco and Sam's Club carry them seasonally. Local grocery stores rarely stock them, so a garden center or home improvement store is your best bet.

What's the difference between a compost block and a bag of potting soil?

Compost blocks are compressed coconut coir that you hydrate yourself, so you pay less per volume and create less packaging waste. Potting soil bags are pre-mixed and ready to use but cost more and take up more shelf space. Blocks are better if you need large quantities; bags are better if you need soil right now.

Do I need any special tools to open and use a compost block?

No. You can break apart a dry block with your hands or a garden fork, then soak it in water in a bucket or wheelbarrow. It expands as it absorbs water. Some people use a drill with a paddle attachment to speed up mixing, but it's not necessary.

Are compost blocks cheaper than buying potting soil by the bag?

Usually yes, especially if you need a large volume. A block that expands to fill a 5-gallon bucket costs less than buying five bags of potting soil. For small projects, the savings are minimal, but for filling raised beds or large containers, blocks are more economical.

Can I return unopened compost blocks if I change my mind?

Most garden centers and home improvement stores accept returns of unopened blocks within their standard return window, usually 30 to 90 days. Check the store's return policy before you buy. Online retailers vary — Amazon typically accepts returns, but specialty gardening sites may have stricter policies.