Plot #59 Trials and Observations

Growbag Trial Update: Good Growth So Far

This year I’m trialling the new SylvaGrow Peat-Free Planter from Melcourt, alongside a ‘bog-standard’ tomato growbag. Here’s a quick update…

This year I’m trialling the new SylvaGrow Peat-Free Planter from Melcourt, one of which I was very kindly sent for the purpose, alongside a bog-standard 50% peat, 50% “forest gold” growbag (which happens to be from Bulrush).

All four tomato ‘Maghrebi’ plants have been growing happily away in the 6’x6′ allotment greenhouse since they were planted out in early June. I’ve been watering them regularly, with as close to the same amount of water per growbag as I can judge, and have fed them a couple of times with liquid comfrey feed, again at the same rate, give or take.

So far all four plants are doing well, but there are noticeable differences:

  • Height – I measured all four plants the other day, from the top of the growing medium to the tip of the highest shoot. Both the SylvaGrow plants had grown to 1.5 metres, and both the Bulrush plants had topped out at between 1.2 and 1.3 metres.
  • Water Retention – On Tuesday morning (when the pics were taken) before I watered, I noticed that whilst the Sylvagrow plants were still nicely turgid, both the Bulrush plants were wilting at the tips (pics below, Sylvagrow first) after their last watering on the previous Sunday afternoon. This tentatively suggests that – given the same amount of irrigation in each planter and as the plants in the SylvaGrow are actually larger, and therefore should be drawing up more water – the rate of evaporation from the peat mix is greater than from the SylvaGrow, causing it to dry out faster.

All four plants have set fruit, which is growing but not showing signs of ripening just yet. I’ve not checked for differences between the size or set-rate of the fruits, but I’m planning to do a quick survey next time I’m down at the plot.

The final proof of this (not-at-all scientific but hopefully quite interesting) trial will be in the harvesting, when I’ll weigh and grade the fruit as they come off the plants.

Further updates to follow.

2 replies on “Growbag Trial Update: Good Growth So Far”

Hi Sue – details of the contents of the Sylvagrow are on their website, ( They do mention green compost but say it’s “carefully sourced and certified so I’d assume that means they’re trying to avoid potential aminopyralid etc. contamination.

No idea about the Bulrush, they just call it “Forest Gold”, which could be anything from sawdust to bark chips…

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