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Ladbrooke soil blockers are a money- and time-saving tool for small farmers or gardeners who start lots of seedlings throughout the year. Here’s why and how to use them. 

If you’ve read our free seed starting ebook or watched our seed starting video classes, then you might have noticed a brief overview of Ladbrooke soil blockers.

No single “right” way to start seeds 

There are lots of different ways to start seeds: direct sowing outdoors, starting indoors in plastic cells, starting indoors in biodegradable pots, etc.

It’s important to note that there is no SINGLE right way to do things for every seed variety. Every seasoned gardener we know ends up developing their own preferences after many years of trial and error. Often, like us, this means they use different methods depending on the seed variety they’re starting.

Do you HAVE to use Ladbrooke soil blockers to start seeds? Nope.

But for some gardeners growing certain seed varieties there are some very big benefits that make Ladbrookes a great choice. Same thing goes for you small farmers out there! 

2″ soil blockers and organic artichoke seeds. Plants that traditionally don’t do well in plastic cells because they don’t like to have their roots disturbed often grow and transplant nicely when started in Ladbrooke soil blocks.

Why Use Ladbrooke Soil Blockers?

We use Ladbrooke blockers when starting seeds that benefit from, or require, germination temps higher than our indoor air temps (which are usually around 70°F when we’re starting our summer seeds indoors in February).

This includes our favorite nightshades like: 

  • tomatoes (germ temps 75-85°F),
  • eggplants (75-90°F),
  • tomatillos (70-90°F),
  • peppers (70-95°F), and
  • ground cherries (75-85°F).

Nope, Ladbrooke soil blocks aren’t warmer on their own right. We have to put the finished blocks on a heat mat and use a heat mat thermostat to bring the soil temps up into the ideal temperature range for optimal germination.

Ladbrooke soil blocks are more space and waste efficient

Can’t you do the same thing with plastic or biodegradable cells too? Yes, but by using Micro 20 3/4″ blockers, we can start 312 seedlings in a single tray. (They’re called “Micro 20″ because they produce 20 small 3/4” soil blocks each time you punch out a set.)

That means, compared to plastic cells or biodegradable pots, the Ladbrooke Micro blocks provide anywhere from 3x – 10x more space efficiency. So unless you want to buy 3-10 more heat mats, Ladbrooke blockers work great when you’re starting a lot of seeds that require high germination temperatures.

Another big benefit of Ladbrooke soil blockers: less waste. You don’t have to buy new plastic seed cells or biodegradable pots if you use Ladbrookes.

Now, if you’re gardening in a small space and you just have a dozen or so seeds you want to start, Ladbrooke blockers may be overkill given your specific needs. You decide…

Tomato and pepper seedlings in Ladbrooke soil blocks getting their first true leaves.

How to Use Ladbrooke Soil Blockers

You’ve got the why figured out, but how in the heck do you use these newfangled Ladbrooke soil blockers to grow seedlings?

First of all, here’s a list of supplies you’ll need to use Ladbrooke soil blokers:

Here’s a step-by-step guide for using Ladbrooke soil blockers:

Step 1. Prep your seed tray.

Put your choice of the following into the seed tray: aluminum foil, parchment paper, or a 1020 mesh insert. A single tray will hold up to 312 3/4″ x 3/4″ mini blocks.

Step 2. Make your soil block mix OR go to the next step if you bought pre-made soil block mix.

Here’s the recipe we use for our SMALL micro blocks (we use a slightly different recipe for our large blocks):

Recipe for SMALL ¾” micro Ladbrooke soil blocks:

  • 4 parts peat moss (we’ve found coconut coir is too crumbly to work well in soil blocks)
  • 1 part compost
  • mix all ingredients together
  • some people also like to mix in all-purpose organic mineral fertilizer at this point to reduce/eliminate the need to apply dilute liquid fertilizer as the seedlings grow.

*The above ingredients need to be passed through a sieve in order to make sure they’re broken up and free of any “chunks.” We use a 1/4” hardware cloth nailed to a frame for this purpose. 

Step 3. Wet the soil block mix.

If you’re using a soil block blend, or once your homemade dry ingredients are mixed, stir in water. Then let the wetted mix sit for 30 minutes to absorb the liquid.

You want the final consistency of the mix to be like wet oatmeal. The soil blockers will squeeze out a lot of water. 

Step 4. Start blocking.

Dip your small 3/4″ mini blocks into a bowl of water. This helps prevent the soil blocks from sticking to the metal as you push them out into your seed tray.

Push soil blocker into damp soil mix, twisting slightly back and forth as you push down. Soil should be very firmly packed into each blocker cube before pushing them out onto seedling tray.

We find it helpful to run your hand along the bottom of the blocker, smoothing out the bottom of the blocks so they sit evenly in the trays.

3/4″ micro blocker, water & soil block mixture

Smoothing the bottom of the blocks out so they sit level in their tray. Sorry for the blurry picture!

Step 5. Push blocks out onto seed tray(s).

Push the soil blocks out of the blocker into position on your seed tray. If you position the blocker vertically, you can get 3 entire blocks snugly across the tray x 5 blocks lengthwise. We add the final rows of blocks by hand, for a total of 312 blocks per tray.

Again, to help prevent soil blocks from sticking to blocker, dip blocker into water each time after putting soil block on tray, before making next round of blocks.

Pressing the Ladbrooke blocks out into a tray

Step 6. Label and record seed varieties.

Place a strip of paint tape or masking tape onto one side & one end of your seed tray. Label the side A-Z and the end 1-12 corresponding to each row.

If you’re using different seed types in each tray, make sure you note the placement of seeds in a google doc or excel spreadsheet. (Example: A1 – B6 = Peacevine Tomato, B7 – C12 = Aunt Molly’s Ground Cherry.)

Labeling your plants from seed to harvest ensures that you know what varieties performed best. Or it means you can grow the things you like best again, save seeds from them, or buy new seeds as-needed.

We label our blocks using painters tape + a sharpie and record the information in a spreadsheet because traditional plant labels don’t work well with this many seedlings. The pink overlay is photoshop magic to show you how the grid works.

Step 7. Add seeds & cover.

Add seed(s) to each block, then lightly cover each cube with either:

  • your soil mixture, OR
  • a dusting of vermiculite (puffed mica).

This helps keep seeds moist/insulated to ensure optimal germination. (*If you’re starting seeds like catnip or chamomile that are labeled “light-dependent germinators,” don’t cover them as they actually need sunlight exposure to germinate.)

Tip: When placing small seeds like brassicas we’ve found it helpful to wet a pencil tip and pick up & place the seeds in their divots. With flatter seeds like tomatoes, eggplants and peppers, using long-handled tweezers seems to make the job a bit easier.

Placing tomato seeds with long-handled tweezers. The parchment is there to separate large blocks of the same type of seed – in this case most of these seeds are ‘Estamino’, an organic tomato rootstock that we use for grafting heirloom tomatoes for better disease resistance.

Step 8. Cover tray and place on heat mat.

Place finished tray on heat mat set to the ideal temperature range for the seeds you’re growing. If you’re doing cool weather seeds with lower germination temps, you won’t need a heat mat.

If you have a dome for the seed tray, put it on now. If not, use saran wrap and tape to make a dome to ensure adequate moisture in the tray.

You don’t need to have your grow lights on at this point since the seeds have not germinated, unless they’re light-dependent germinators.

Step 9. Mist and wait.

Using a spray bottle (one that lasts for years), lightly mist the tops of the blocks each morning and night (12 hour cycle) until the seeds germinate to ensure they stay damp, but not wet, like a well wrung out sponge. There should not be standing water in the bottom of your tray.

Step 10. Germination: remove dome, add light.

Your seedlings start to sprout – yay! Now, you’ll want to immediately do two things:

1. Remove the plastic or saran wrap dome. After germination, a fungal disease called “damping off” can kill your seedlings if the moisture levels and air circulation are inadequate.

2. Put your seedlings under grow lights (here’s the DIY setup that we use). We keep our grow lights about 2-3″ above the top of the plants.

If you don’t have grow lights, keep them in front of a sunny, south-facing window. Even then, with modern energy efficient windows, it’s hard for your seedlings to get enough light indoors without grow lights.

Step 11. Go through cotyledons and true leaves stage.

After germination, your seeds will send up plumules (stems) with small cotyledons (embryonic first leaves) on the tips. 7-10 days later, they’ll develop their first “true leaves” that resemble the leaves of the mature plants.

As they get longer root systems, you can switch to watering by gently pouring water into the bottom of the tray. The plant roots will help hold the blocks together.


Tomato seedlings developing true leaves in small Ladbrooke soil block. The tomato seedling on the right is actually a bit too “leggy” since it was too far away from the grow lights, but it will recover once potted up and provided with adequate light.

Step 12. Block them up.

Pepper seeds blocked up from the 3/4″ micro blocks into the 2″ mini blocks.

After your seedlings have formed true leaves, you’ll want to “block up” your seedlings to the next size of Ladbrooke soil blocks. (The 2″ Mini 4 blocks + 3/4″ cube inserts, which attach to the 2″ block and make a perfect 3/4″ cube-shaped void in the center so you can nest the 3/4″ mini blocks inside.)

If you don’t want to use a pre-made soil blocking blend, use the recipe below for your larger blocks (we use a slightly different recipe for our small and large blocks):

Recipe for LARGE 2” Ladbrooke soil blocks:

  • 5 Gal sustainable peat (we’ve found coconut coir is too crumbly to work well in soil blocks)
  • 5 Gal Compost
  • ¾ Gal Sand
  • ¾ Gal Vermiculite
  • screen peat and compost through 1/4” screen or hardware cloth so no chunks


1. Screen the dry materials 

The above ingredients need to be passed through a sieve (we use a 1/4” hardware cloth nailed to a frame) in order to make sure they’re broken up and free of any “chunks.” Once sifted, thoroughly mix all dry ingredients together in a large bucket or wheelbarrow.

Some people also like to mix in some all-purpose organic mineral fertilizer at this point to reduce/eliminate the need to apply dilute liquid fertilizer as the seedlings grow.

2. Wet and mix.

Once your dry ingredients are mixed, stir in water, then let the mix sit for 30 minutes before blocking. You want the consistency of the mix to be like wet oatmeal – if it’s too dry, your blocks won’t hold together.

Step 13. Harden off seedlings, then transplant.

The time between germination and transplant should be 6-8 weeks. Any longer and you risk stunting your plants due to inadequate root growth area.

During this time, keep your soil blocks damp but not wet. Also, keep your seedlings under 10-12 hours of grow light time per day.

A week before transplanting, you’ll want to “harden off” your seedlings. This simply means acclimating them to direct outdoor sunlight, which is more intense than grow lights. If you don’t harden them off, they can become severely sunburned or be killed.

Chicory hardening off before being transplanted. Due to its large taproot, chicory typically doesn't start indoors and transplant well - but it does quite well in Ladbrooke soil blocks.

Chicory hardening off before being transplanted. Due to its large taproot, chicory typically doesn’t start indoors and transplant well – but it does quite well in Ladbrooke soil blocks.

Plan to harden your seedlings off outdoors over the course of a week as follows:

  • Days 1 – 3: Place your seedlings outdoors in a shady spot that will only get 3-5 hours of direct sunlight throughout the day.
  • Days 4 – 5: Place your seedlings in a slightly sunnier spot that will get about 5-6 hours of direct sunlight.
  • Days 6 – 7: Place your seedlings in a full sun spot.

Finally, always check your 15 day weather forecast before transplanting your seedlings outdoors. Frost, freezes, severe weather… these can cause a lot of heartache, so plan accordingly!

You’ve now successfully grown your own garden seedlings using Ladbrooke soil blockers! 

Read our article about tips for getting your new transplants established outdoors in their final spot in your garden.

Happy Gardening!

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