Making Blocks: Step by Step

Every Swift Blocker follows the same rhythm — fill, scrape, lift, seed — whether you're pressing four blocks on a windowsill with a Nano or two hundred in a 1020 tray with a Commercial model. Here's the whole process, from wet mix to seeded tray, with a checkpoint at every step. A few places the technique changes by size are called out as you go.

Nano vs. Commercial, at a glance

Same tool, two scales. Three places the technique differs by size:

	Nano	Commercial
Footprint	Under 5″ square — any small tray or reused container	A standard 1020 tray
Loading the cells	Fingertips for the smallest sizes; heel of your palm for the Nano 4/9	Heel of your palm — the cells are large enough throughout
Ejecting	Lifts straight up and releases cleanly on its own	Ease it loose with a back-and-forth rocking motion, back edge first

Phase 1 — Prepare the mix

1. Wet the mix. Add warm water a little at a time, kneading between additions so moisture reaches every part evenly — dry pockets in the middle produce weak spots in the finished block. On the smaller Nano cells a mix that's too dry shows up as crumbling almost immediately, so it pays to be thorough here.

   Done when: a squeezed clump releases a drop or two of water between your fingers, and still holds its shape when you open your hand.

   If no water comes out: the mix is too dry — add more warm water and knead again before moving on. A mix that feels almost right here will be too dry to hold a block.

Phase 2 — Load the blocker

2. Set the blocker on a flat, firm surface. A Commercial model sits with the bottom tray underneath it; a Nano sits directly over a small tray or any solid-bottomed reused container under a 5-inch footprint.
3. Grab mix and push it into the cells. Use the heel of your palm to press down on the larger cells — not just your fingertips; switch to fingertips for the smallest Nano cells.

   Done when: the mix doesn't compress any further and there's no visible gap between the mix and the cell wall.

4. Work the corners of each cell last. Push a small extra pinch into each corner with a fingertip and press again.

   Why this matters: a rounded handful covers the center but bridges across corners, leaving an air pocket. Blocks that crumble at transplant almost always broke from an under-packed corner.

5. Leave the frame intentionally over-stuffed — mix should mound slightly above the top edge across the whole frame.

   Done when: there's a visible ridge of excess mix above the top edge everywhere. Any low spots mean a cell underneath isn't fully packed — add more mix and press again before scraping.

6. Scrape the top flush with the Swift Scraper held flat across the top edge, one pass from back to front.

   While scraping: feel for any resistance from sticks or debris and pull them out — anything left catches during ejection and drags a block out of shape.

   Done when: the top is flat and level with no hollow spots, and the scraper came away clean.

Phase 3 — Eject the blocks

7. Set the top tray flat on top of the loaded frame. Press it down gently so it seats evenly — don't press hard.
8. Lift the bottom tray up through the top tray. On Commercial models, use a back-and-forth rocking motion — ease the back edge up first, then the front. The Nano is simpler: lift it straight up and it releases cleanly on its own, no rocking needed.

   Done when: all blocks are standing upright with sharp edges and flat tops. The lift should feel like opening a stuck jar lid — firm but not a struggle.

   Won't release: the mix is too dry. Don't force it — that tears blocks in half. Re-pack with wetter mix.

   Blocks slump or won't stand: mix is too wet or a cell was under-packed. Stir a small amount of dry mix into the remainder before the next press.

9. Lift the blocker frame away. Rinse it now if mix is drying on the frame — dried-on mix makes the next ejection harder.

Phase 4 — Seed and cover

This is where the seed-before-eject trick pays off: if you sowed into the bottom tray before pressing and dusted it with vermiculite, this step is already done. If not, here's the after-eject version — a pinch of zinnia seed or a single tomato seed per dimple, whatever you're sowing, seated the same way.

10. Press each seed firmly into its dimple so it's touching moist soil on all sides — not resting on an air gap in the center.

    Contrast: a seed touching soil on all sides germinates; a seed resting in an air pocket won't, even if the rest of the block is moist.

11. Cover with a thin layer of fine vermiculite — just enough to hide the seed. A slightly drier version of your soil mix also works.
12. Move the tray to your germination setup — grow lights, heat mat, and humidity dome as usual. Bottom-water from the start; see Watering for the full routine.

What good blocks look like — and what to watch for

A correctly made block has sharp edges, stands upright without leaning, and doesn't crumble when you pick it up. The surface is a uniform dark brown with no pale dry patches. Roots will fill the block and stop at the edge (air pruning) rather than circling as they would in a plastic plug, so the root ball lifts out cleanly at transplant time — how soon depends on block size; see When to Start Seeds for the size-by-size timing.

Quick reference — symptoms and fixes

• Blocks crumble: under-packed or under-wetted. Pack harder and wet the mix more.
• Won't release: mix too wet. Stir dry mix into the remainder.
• Seeds don't germinate: seed not touching soil. Press each seed in firmly.
• Mix sticks to top plate: skipped vermiculite when seeding before pressing. Always cover seeds with vermiculite before ejecting.

Before your first tray

Answer these three without looking back:

1. What should a squeezed clump of mix do when the moisture is right?
2. Which part of each cell is most likely to be under-packed?
3. How much effort should ejecting the bottom tray take?

If you're confident on all three, you're ready to mix your first batch.

More options: large seed, pre-sprouted seed, and seeding before pressing

Do I need to do anything special with large seed, like pumpkins or squash?

Soak large seed overnight before sowing it directly into a block. A dry seed swells as it takes up water, and if that happens inside a tightly packed block it can crack the block open from the inside. Soaking first lets the seed swell before it's in the block — this matters most on the bigger cells (Nano 4, Commercial 50, the Dahlia Blocker).

Can I transplant a pre-sprouted seed straight into a block?

Yes — sprout the seed on a damp paper towel first, then lift it out with tweezers and set it into the block's dimple, covering lightly with vermiculite. A larger cell — the Nano 4, or the Dahlia Blocker — is a good match for this. For very small seed, skip the paper towel: the new root tends to bind into the paper fibers and tears when lifted. Sprout small seed on a moist medium in a shallow container instead, where it releases cleanly.

Can I sow seeds before the blocks are pressed out?

Yes — once the bottom tray is filled and scraped smooth, place a seed in the center of each block in the tray before pressing anything out. After placing every seed, sprinkle the whole tray with vermiculite, then press out as normal. Don't skip the vermiculite: the clay in the mix turns sticky once wet and will cling to the top plate without it — especially noticeable with pelleted seed.