Seed Starting 101

Start your seeds in soil blocks to produce robust transplants for your garden without the wasted expense of starter pots.

Compressed soil blocks have been used by farmers for years. Serious gardeners have also discovered the benefits of using custom soil blends to produce strong, healthy transplants without the use of pots. The extra step of compressing the soil into a block is easily offset by the greater volume of undisturbed root mass which translates into a rapidly maturing, pest resistant transplant. Ready to up your gardening game?

Seedlings in Soil Blocks

Seedlings in Soil Blocks

Seed starting in soil blocks reduces transplant shock.

Photo by: Debbie Wolfe

Debbie Wolfe


  • soil blocker tool
  • soil blocker mix
  • water
  • tray
Metal Soil Blocker Tool

Metal Soil Blocker Tool

A metal soil blocker tool can make multiple blocks of soil at a time.

©Debbie Wolfe

Debbie Wolfe

Some Notes About Supplies

As with all things gardening, there are options at each step in the process, supplies included. The cost of a basic soil blocker that produces four 1.5 inch blocks is reasonable.

Hand Pressing in Wet Soil into Soil Blocker Tool

Genlty Press in Soil into the Soil Blocker

The soil mix used to make soil blocks has the consistency of oatmeal once water is added.

Photo by: Debbie Wolfe

Debbie Wolfe

After trying some of the DIY blocker options, we have come to the conclusion that the factory made models are worth the money. We do make our own blocking mix out of peat moss, vermiculite, compost, garden soil, powdered lime and organic fertilizer. For a gardener just getting started in the use of soil blocks however, the price of ready-made blocking mix is fair. As for water, we prefer either rainwater, distilled water, or day-old tap water so that chemicals used in water purification are minimized. The tray is for receiving the newly made blocks and possibly seeding, not for growing. It should have a firm, flat bottom. Plastic is easy to keep clean, and lasts for many plantings. We use an old baking sheet pan.

Adding Water and Filling the Blocker

Hand Pressing Soil Blocker Tool

Press Soil Blocks Onto a Tray

A soil blocker tool can make multiple blocks at once.

Photo by: Debbie Wolfe

Debbie Wolfe

To get started, place some of the blocking mix into a flat bottomed container for wetting. Reserve some dry blocking mix to add in as water is squeezed out during blocking and the slurry gets “soupy.” Stir in enough water to make a slurry with the consistency of oatmeal. Don’t worry about getting it perfect. You can always add a bit more water or blocking mix to adjust the texture.

Make the Blocks

Soil Block

Tray of Soil Blocks

Soil blocks are an effective way to start seeds.

Photo by: Debbie Wolfe

Debbie Wolfe

Start by dipping the blocker into water. This will prevent the blocks from sticking when you attempt to eject them. Next, press the blocker into the slurry, twisting your wrist slightly as you firm it against the bottom. Pick up the blocker, and use either your hand or a flat instrument (like a spatula) to remove excess mix from the bottom of the blocker. Finally, hold the blocker firmly against the bottom of the tray and squeeze the release as you pull the blocker off the blocks. It sounds like a lot of steps, but it takes maybe ten seconds from initially pressing into the slurry until the blocks are released.

Make a lot of Blocks

Soil Block with Seeds

Single Soil Block with Seeds

Add a couple of seeds to the little depression on top of the soil block.

Photo by: Debbie Wolfe

Debbie Wolfe

Make more blocks than you think you will need. Especially during the first few attempts at making blocks, there will be a few duds. If the blocks are too wet, or fall apart, simply throw them back into the slurry for reuse. This process is best done all at once, prior to seeding, because it takes space and time. Plus, when you are in a rhythm you don’t want to stop and plant, then restart.

Add the Seeds

Once the blocks are made, it’s time to seed. For most vegetables, herbs and flowers, one or two seeds per block will be plenty. We have consistently experienced high germination rates, and feel that it’s easier to toss a couple of empty blocks where seeds did not germinate back into the blocking mix, rather than spend time thinning 98 blocks that were seeded too heavily.

Caring for Soil Block Seedlings

Seedlings in soil blocks need the same care as other young plants. Keep them consistently moist, covering with plastic until the seeds sprout. When the blocks begin to feel dry to the touch, the best ways to provide water are either through “flooding” or “fogging.” Most home gardeners will find that flooding is the simpler method: place the tray into a container of water that is up to half the depth of the blocks, and allow them to absorb as much as they will for five or ten minutes. Fogging requires a micro-mist for five to ten minutes at a time.

As with all seedlings, once the plants have sprouted, they require very bright light in order to develop properly. Indoors, supplemental fluorescent light, twelve hours a day, two inches from the foliage is adequate. Harden the seedlings off gradually, prior to planting in the garden. Do not break up the roots at planting time.

The expansive, undisturbed root system of seedlings in soil blocks will out-compete weeds in a well prepared garden bed. They will establish very quickly, with almost no transplant shock. Their overall vigor makes them highly resistant to insect and disease infestations. For quality, health and economy of labor, try soil blocks.

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