Which Blocker Is Right For Me?
Every Swift Blocker makes the same kind of block — the question is how many at a time, and how big. Match the tool to your batch size: the Nano fits a windowsill and starts a home garden, the Mini fills backyard-market batches, and the Commercial line presses a full 1020 tray of market-farm seedlings at once. Two minutes below and you'll have your answer.
Find your fit
Question 1 of 3
What are you using it for?
How many blocks do you press at once?Each tray below is drawn at its real cell count.
What will you mostly grow?Blocks are drawn to scale against each other.
- Does block size matter for different seeds?
- How long can a seedling stay in each block size before it needs to come out?
- Best for home gardeners and small spaces
- Best for backyard market gardens
- Best for market farms and high-volume growers
- What if I'm potting up cuttings or larger seedlings?
- Frequently Asked Questions
Does block size matter for different seeds?
As a general rule, smaller blocks suit small, fast-sprouting seeds, and larger blocks suit bigger seeds or anything that will sit in the block longer before transplant. A smaller block also dries out faster and needs potting up sooner, so match the block to how often you can realistically check on it.
How long can a seedling stay in each block size before it needs to come out?
Each block size has a rough ceiling, regardless of how fast a particular crop grows — these are working ceilings, not stopwatch numbers:
| Block size | Rough ceiling |
|---|---|
| 0.9″ | ~3 weeks |
| 1.125″ | ~3–4 weeks |
| 1.5″ | ~4–6 weeks |
| 2″–2.25″ | ~6 weeks |
Past that point the block itself becomes the limiting factor — it dries out or runs out of root room — even for a crop that would otherwise be happy to wait longer. Soil-blocked seedlings also tend to reach transplant size noticeably faster than the same crop in a plug tray, so if you're working from a plug-tray seed-starting chart, expect to transplant earlier than it says. Naturally slow growers like lisianthus or delphinium will outgrow even the largest standard block before they're garden-ready, so plan to pot those up partway through rather than holding them in one block the whole way.
Best for home gardeners and small spaces
The Nano series reuses kitchen-waste-size containers and trays, making it the easiest entry point into soil blocking. It comes in four cell counts and block sizes — 25-cell at 0.9 inches for tiny, fast-germinating seed; 16-cell at 1.125 inches and 9-cell at 1.5 inches for most everyday vegetables, herbs, and flowers; and 4-cell at 2.25 inches for larger seed or anything you'll hold in the block a bit longer before transplanting. The 25-cell's 0.9″ blocks are where most cut-flower seed wants to start — zinnias, snapdragons, celosia — while the 4-cell handles sweet peas and squash.
Best for backyard market gardens
The Mini series is the step up from Nano: sized for a smaller footprint than the Commercial line, but built for more volume than a single tray. The Mini 75 makes the same fine, 0.9-inch block as the Commercial 200; the Mini 27 makes the same 1.5-inch block as the Commercial 72 — so you get Commercial-size blocks at backyard-market batch sizes — a flower farm's workhorse density, scaled down.
Best for market farms and high-volume growers
The Commercial series (50, 72, 128, and 200 cell) fits a standard 1020 tray and is built for repeated daily use. More cells per press means a smaller block and faster turnover for high-volume seeding; fewer, larger cells suit crops you'll grow on longer before they go in the ground — tomatoes, peppers, and the flowers you're bumping up rather than germinating fresh.
What if I'm potting up cuttings or larger seedlings?
The Dahlia Blocker, in the Commercial collection, is built specifically for potting up dahlia cuttings, melons, pumpkins, and other larger transplants. It's also a good choice if you pre-sprout larger seed on a damp paper towel before blocking — the bigger cell gives a transplanted sprout room to grow right away. See Making Blocks: Step by Step for that technique.
Prefer a chart? See the size guide.
Frequently Asked Questions
Which Swift Blocker is right for me?
Home gardeners and small spaces are best served by the Nano series; backyard market gardens fit the Mini series (27 or 75 cell); market farms and high-volume growers should choose the Commercial series (50 to 200 cell). For potting up cuttings or large seedlings, the Dahlia Blocker is purpose-built for that job.
Does soil block size matter for different seeds?
Yes — smaller blocks suit small, fast-germinating seeds and dry out faster, while larger blocks suit bigger seeds or transplants that will sit in the block longer before going in the ground.
Keep growing: Soil blocking 101 · Size guide · When to start seeds — or Shop all blockers