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Bumping Up

Soil blocking can be a bit of a pain - getting the moisture level right in the growing medium, packing and setting out all of those little squares - but I've had fewer problems with disease or pests since I went to soil blocking. The plants seem to thrive (perhaps because the blocks use more soil than other methods) and I can easily clean and reuse trays.

The other cool thing about soil blocking is how they are designed for repotting, i.e., 'bumping up.' The model I use has 1/2", 1 1/2"* and 2" squares. The 2" squares come with a 1/2" square insert so that a nice clean square is molded in the soil block into which the 1/2" blocks fit perfectly.

A full tray of 1/2" blocks is 300 blocks. Since the same tray holds only 48 of the 2" blocks, I do sometimes face a dilemma - fill lots of trays, or cull to the best seedlings. My general approach is to plant 60 of each variety in a 300 block tray, and then keep the best of those.

This method is probably not efficient for large-scale planting, but the quality we get from each balances it out for us. Bumping up today:

  • Veronica Alba (white Veronica)

  • Iceland Poppies 'Champagne Bubbles' (I usually have tons of these but for some reason had poor germination this year. Unfortunately, we've run out of seed)

  • Himalayan Poppies

  • Stock

* The 1 1/2" blocks are used for starting larger plants that grow quickly like zinnias, amaranths, tomatoes and even melons. They will not be transplanted into larger sizes.


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