A quick recap on my last facebook post on this subject. Over the last 20 years, we have used several different suppliers of horticultural composts. Some were amalgamated or bought out, others we changed as we sought local suppiers and more recently, better quality in peat free composts. 3 years ago, a difficult decision had to be made. We had enjoyed a great relationship with Godwin’s over the years but their peat based business was not keeping up with the times and their lack of commitment to quality of the peat alternatives in their products was severely compromising the efficacy of the final produce. In 2021 we moved to Melcourt Industries, a company with unsurpassed experience in peat free substrates and we had many nods of approval in the quality of their range. We had no intention of changing until a sample arrived on our doorstep from a Somerset company, who were using digestate from their own farm based digester, thus avoiding the use of imported coir and woodchip. This ticked several important boxes for us. The bulk of the product was the reuse of a substrate that had already been used for energy production (rather than being produced and transported simply to make compost). Reuse drastically reduces the carbon footprint of any raw material. The fact that it was farm based and located in Somerset ticked another two boxes. The fact that it is cheaper than the Melcourt products is perhaps not a surprise, given that there is greatly reduced transport and the fact it is also certified as Organic is another bonus. But what is it like to use?
RocketGro is a young company but they are not fly-by-nights. They have clearly done their research, are continually adapting and have first class merchandising. However, I’m keen to experiment in our nursery and to hear from others about how their products are performing in the garden.
I apologise if I have used this analogy before, but you can’t buy and electric car and expect it to perform as if it had a petrol or diesel engine. You need to sit back and change your driving strategy to ensure that you maximise the benefits of electricity and minimise the down side. Critics that simply try to compare like with like are missing the point entirely. The same with peat free composts. The dangers are the moisture capacity (how much water will it hold, how quickly will it dry out and how hard is it to rewet), How coarse is the product, does it cap when over watered or is it too loose allow roots to easily spread within it. In the past, high conductivity (concentration of nutrients) has been inconsitent, primarlily because of the use of compoted organic waste as a major constituent. For anyone who has watched their seedlings germinate, only to turn yellow and fade away will understand. High conductivity often results in the concentration of nutrients being higher in the compost than in the roots of the young plants. This results in reverse osmosis and water actually being drawn out of the plant, hence it dying. Excessive nutrients in a compost is often indicated by the white salts appearing on the surface. This are the nurtrient salts being left behind after the moisture has evaporated off.
It is too early for me to draw firm conclusions but here are my observations so far:
Across the product range, the consitency of the digestate is remarkably similar and consistent. It is definately coarser than the Melcourt composts but contains plenty of smaller particles, so that the overall consistency is not far of an unprocessed peat. Unlike peat, it has a strong odour which I would associate with “farmyard” I think this is no bad thing but may come as a surprise to first time users. It certainly smells like it means business. So farm, I have used the container mix and the tree & shrub mix for hanging baskets and potting on fruit trees. Both are simply peat free composts and both seem to handle the same, although the substrate compostition is obviously subtly different. When wet it is spongy and the top surface does dry out redily. However, the compost does hold a lot of moisture and surprisingly, the stated warning is to be careful of overwatering. The composts certianly do re-wet easily if allowed to dry out, which is a bonus compared with most peat alternatives and I would say it is easier to re-wet than peat itself.
I have also tried the Multipurpose compost, which has added loam (or at least the constituents of loam). The addition clearly makes the compost heavier and the particles of sand and clay are clearly visible in the compost and on my hands after using it. I have used this compost to sow larger seeds in, such as beans and sweetcorn, but I think it is too loose to guarantee germination of smaller seeds. That said, I spilt a few lettuce seeds into my bean compost and they seem to have germinated in record time!
Smaller seeds I have used the Seed and Cutting compost and there is a dramatic difference in the consitency of this compost, compared to all the others in the range. It has been finely processed and has enough loam to make it almost seem like a fine loam. It is well drained and does not cap, unlike some peat based seed composts. So far it has performed well and the photos show that at the moment, everything had germinated and looks healthy.
I have done quite a bit of experimenting and going forward, for larger seeds I will probably use Multipurpose in the base of the modules and use seed compost as the top dressing. This is mainly because the coarser MP compost does look a bit coarse for the small modules. Having finer compost on the top will hopefully reduce moisture loss.
I’m obviously a bit nervous at the moment and hoping for the best but at the moment, all looks good. I would be very interested to hear about customers experiences, good or bad, and perhaps we can help eachother learn how to maximise the benefits of RocketGro composts?