Soil blockers – reflections on using them for a season

Soil Blockers (mini on the left, medium on the right)

I have to admit we are sometimes tempted by the odd gadget or two and last year at the Flowers from the Farm conference in Birmingham we were tempted to buy some ‘Soil blockers’.

One of the reasons for purchasing these was an ambition to try and reduce the amount of plastic, particularly plastic pots, we use for propagation. The ‘Soil Blockers’ allow you to create individual blocks of compost which you can sow your seeds into directly.

The Ladbrooke ‘Soil Blockers’ we bought come in three sizes; a ¾ inch mini block, a 2 inch medium block and a 4 inch large block. One very interesting feature is that using a special indent the mini block can be neatly slotted into the medium block and the medium block can be slotted into the large block when you want to transplant your developing plants. We purchased the mini and the medium sized blockers.

Mini Soil Blocker from underneath showing the shaping that creates the indent for each seed
Mini Soil Blocker from underneath showing the shaping that creates the indent for each seed

In theory the air around each block stops the roots of different plants tangling together and they are therefore less prone to damage when you come to plant out in the garden.

Medium Soil Blocker from underneath showing the shaping that creates the indent for each seed
Medium Soil Blocker from underneath showing the shaping that creates the indent for each seed

So how did we get on.

Creating the compost blocks works very well. Each block comes neatly out of the blocker and has a small dibble (technical term!) in the top to allow you to place your seed in. The down side is that loading the blocker with damp compost can be a rather messy business. We tend to start sowing early in the season to give our plants a good head start. Because it is cold and miserable outside we often work in the snug kitchen sowing seeds and pricking out. It is quite easy to sow seeds indoors with dry compost in small seed trays which you can carefully water but really not practical using large buckets of damp wet compost and a soil blocker. Really a job for the greenhouse only.

Compost blocks
Moist compost blocks in standard seed tray ready to receive the seeds

Being able to sow individual seeds in separate blocks made good use of expensive F1 seed in particular and the seeds did seem to germinate very well.

One seed (in this case garden peas) is placed in each indent ready for germination
One seed (in this case garden peas) is placed in each indent ready for germination
Indent filled with fine vermiculite to cover the seed keep the soil and seed moist
Indent filled with fine vermiculite to cover the seed keep the soil and seed moist

Our main problems began to emerge once the plants had started to grow. We found it quite difficult to keep the blocks moist enough. This was particularly the case for the smallest mini blocks. Watering from above tended to break down the compost blocks we had carefully created so the only satisfactory way to keep them adequately moist was to place the trays in a shallow bath of water and leave them to soak. This worked well but was extremely time consuming and was not really practical for the large number of seed trays we have to deal with each year.

The idea of being able to slot a mini block into the larger medium block also appealed but we found this to be very time consuming and we soon lost patience with this approach.

Over time we stopped using the mini block and sowed our seeds directly into the medium block. When the plants were large enough we either planted the blocks directly out into the garden or potted them up into larger plastic pots as appropriate. The roots held the blocks together very well and we did find them extremely easy to plant out or pot up at speed.

We found that some plants thrive better than others in the blocks – probably because we were struggling to keep them all watered well in the greenhouse and polytunnels as the weather warmed up. I was quite surprised to find that the medium blocks worked very well for podding peas for the vegetable garden. Because I loose a lot of seeds to mice and voles if I sow directly into the ground I have for a number of years started my peas off in modules and then planted these into the ground when they are big enough to look after themselves. Sowing individual seeds into the medium blocks created strong robust plants which then grew away wonderfully well when planted out. There was little or no disturbance to the roots and I think they appreciated this.

The fact that we have brought the ‘Soil blockers’ out to use again for a second year I think shows they are a valuable addition to our gardening equipment. I don’t think they actually saved us much time or reduce the number of pots we use but for some plants they worked very well indeed. In reality we use our plastic pots again and again, year after year. The watering was a real problem and so I suspect we will only use the ‘Soil Blockers’ this year for seedlings that really hate root disturbance and worked well with this approach.

Further information

Ladbrooke Soil Blockers are available from www.soilblockers.com

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2 thoughts on “Soil blockers – reflections on using them for a season”

  1. Very helpful post – thank you! Like you, I tend to use my plastic pots time and time again. I have been considering moving to newspaper pots for things that I know will grow on very quickly in spring…..but actually, I find I don’t have very much newspaper anymore!!! I will give it a try though..

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