Stop Guessing Which Soil Blocker to Buy. Answer These 4 Questions First.
Some links in this article are affiliate links — if you buy through them, we earn a small commission at no extra cost to you.
Here’s the thing nobody tells you before you buy a soil blocker: the mini blocks are not for beginners. They look like the obvious starting point — cheap, compact, make 20 at a press — but they’re actually the hardest size to use and the most likely to send a first-time soil blocker back to plastic cell trays forever.
The soil blocking world has a clear hierarchy, and most guides bury the lede. So let’s skip the preamble: answer four questions, and you’ll know exactly which blocker to buy.
Question 1: Have you ever soil blocked before?
If no: Buy the 1.5” Medium Blocker. Full stop. Come back to this guide when you’ve used it for a season.
If yes: Keep reading.
The medium blocker is the unanimous starting recommendation across every experienced voice in the soil blocking community. “If you’re going to just choose one soil blocker to start with, I would highly recommend this medium one.” The block size is forgiving enough that most seedlings go straight to the garden without needing to pot up, the blocks hold together reliably, and it works for the widest range of crops.
Medium Blocker (1.5”, 5-cell) · ~$40 · Buy on Amazon
The one limitation worth knowing upfront: if you later decide you want to pot up within the soil block system, the medium doesn’t fit into a 2” block cleanly. The geometry doesn’t work — the soil collapses around the insert. If you eventually want a block-to-block potting system, you’ll need the mini + 2” combo, not the medium + 2”.
Question 2: How many seeds do you start per season?
| Volume | Right tool |
|---|---|
| Dozens to a few hundred | Medium (1.5”) or 2” blocker |
| Hundreds to low thousands | Mini (3/4”) + 2” combo |
| Thousands | SwiftBlocker |
If you’re a home gardener with a few trays, the medium handles everything sensibly. The 2” blocker is worth adding if you grow a lot of tomatoes, cucumbers, or peppers — more on that below.
If you’re at the scale where you’re timing your seed starts by the flat and counting germination rates carefully, the mini’s 20-block-per-press throughput starts to matter. You plant one seed per cell, pot up only what germinates into 2” blocks, and never waste space on dud cells. It’s efficient — but “if you can get good mini blocks, that is the sign of a good soil blocker, because the small ones are the most finicky.”
At market-garden scale — thousands of seeds, hundreds of flats — the SwiftBlocker is in a different category entirely.
Question 3: What crops are you starting?
Greens, brassicas, herbs, cut flowers: The 1.5” medium handles all of these without potting up. The Standing 35 is also excellent here — more on that in a moment.
Tomatoes, cucumbers, peppers, squash: This is where the 2” blocker earns its keep. The larger block means you’re building a substantially bigger root system before transplant. One grower documented harvesting ripe cucumbers two to three weeks faster after switching from smaller blocks to 2” — the transplant size advantage is real for long-season fruiting crops.
2” Blocker (4-cell) · ~$40 · Buy on Amazon
The trade-off is space. Two-inch blocks take up significantly more tray real estate per plant, and they use more soil mix. For a tray of lettuce, that’s overkill. For 12 tomato transplants, it’s the right call.
Question 4: Do you have physical limitations or just really hate kneeling?
The Standing 35 is the only blocker in this category designed for upright use. You press from a standing position — no bending to tray level required. It makes 35 blocks per press and fills a standard 10x20 flat with three pressings (105 plants). At roughly 1.25” per block, most crops go straight to garden without potting up.
Standing 35 Blocker (1.25”, 35-cell) · Price varies · Buy on Amazon
It’s genuinely underrated for people growing greens and flowers at mid-volume. The ergonomics alone justify it if kneeling over trays is a problem.
The SwiftBlocker: Only If You’re Growing at Scale
SwiftBlocker (200-cell, ~1”x1”) · ~$300 · Buy on Amazon
The SwiftBlocker is an American-made tool (Michigan) that produces 200 blocks in a single press into a standard 10x20 flat. The time savings at high volume are dramatic — and it’s also, as one market gardener noted, “probably way more soil blocking than you need if you are a home gardener.”
At $300, this only makes sense if you’re starting enough seeds to feel the time cost of hand-pressing a few blocks at a time. The blocks are slightly larger than standard minis (~1”x1”), which means they dry out a little less aggressively. Compatibility note: it requires a flat-bottom tray with no drainage channels — standard seed trays with ridged bottoms won’t work.
If you’re a market gardener who’s been hand-pressing minis by the hundreds per week, this is worth every dollar. For everyone else, it’s a novelty.
The Mini Blocker: Last Resort, Not First Choice
Mini Blocker (3/4”, 20-cell) · ~$30–$40 · Buy on Amazon
The mini produces 20 blocks per press and is the most space-efficient option by far. For crops where germination is unpredictable — starting one seed per cell and only potting up what germinates — it eliminates wasted tray space.
But the cons are real: mini blocks dry out significantly faster than larger sizes and require more attentive watering. The corners tend to stick and blocks can fall apart during pressing. And critically, they don’t pot up cleanly into the 1.5” medium — they only pair with the 2” blocker.
“Con: they are finicky to use. These are the hardest ones to press out.” If you haven’t already gotten the feel for a well-formulated blocking mix and a clean press, the mini will frustrate you.
What No One Tells You About Soil Blocking Equipment
The mix matters more than the tool. Blocks that crumble aren’t a tool problem — they’re a mix problem. A proper blocking mix (peat or coir, compost, perlite, lime, blood meal or similar) compresses differently than generic potting soil, which will fail. Your blocker is only as good as what you’re pressing.
Tray selection is non-negotiable. Trays with drainage channels cause blocks to tip and degrade. You need flat-bottom trays with low side profiles — the low sides allow air to circulate around the blocks, which reduces algae and fungal issues. This isn’t optional at any scale.
Maintenance is minimal but matters. Don’t leave blockers submerged in water between uses. If they start squeaking, a little oil on the metal parts keeps them going indefinitely. A properly maintained blocker is essentially a forever tool.
One thing to specifically avoid: peat-based blocking mixes from brands that can’t confirm PFAS-free status. A few sources called this out specifically. If you’re using peat, it’s worth checking.
The Short Version
If you read nothing else: buy the 1.5” medium blocker first. It’s the right tool for most home gardeners and the right way to learn whether soil blocking is for you before investing in a full system.
Once you’ve got a season under your belt:
- Growing lots of tomatoes and cucumbers? Add the 2” blocker.
- Want to scale up throughput efficiently? Add the mini (paired with the 2”, not the medium).
- Kneeling is a problem? Skip everything else and get the Standing 35.
- Running a market garden at real volume? The SwiftBlocker is what you’re looking for.
The worst move is buying the mini first because it’s the cheapest and looks approachable. It isn’t. Start with the medium, and work your way out from there.