~ Margaret Atwood
I’ve been experimenting again. And since it is time for many of us to get seeds started for some fall vegetable crops I thought I’d give you another peat free option for indoor seed starting.
Hydroponics is the process of growing crops in water with no soil. Well known to those who grow hydroponic is rock wool. Historically rock wool has been used for decades in some European countries for housing insulation. Today it has been adapted for commercial applications around the world to grow our vegetables in greenhouses. Rock wool is a product of super heated rock until it sort of explodes into fine filaments, kind of like cotton candy (candy floss), then is formed into a usable material. At least that’s my loose translation of what it is. You can get a more detailed explanation at http://grodan101.com/about-us.
Rock wool for seed germination is formed into cubes. It is all natural and chemical free. Each cube is wrapped in plastic which makes it easy to write your planting date and seed variety on the side. It is said to be a biodegradable plastic, but I prefer to remove it when I plant them into the soil, so the roots that emerge out the sides are not hampered in any way. I doubt it biodegrades very quickly. After all plastic is plastic and I don’t want it in my garden. Maybe someday they will change it to a paper wrap. In my situation I don’t need it to be wrapped at all but I suppose commercially the big growers do.
The manufacturer states that rock wool is recyclable but, I think more likely only at the commercial level of use rather than for the average home gardener. Since it is made of rock it does not decompose so as we use a few each season they are more likely to end up in our compost piles after we clean out our vegetable beds at the end of harvest. Crumbling them up into smaller pieces as you find them, they will provide a means of looser soil structure adding to your soil’s tilth, much like stones or sand provide, helping drainage and bringing air down into the soil.
Rock wool cubes are a good choice for starting seedlings because of its air/water transferability. There is little risk of rotting seeds from being too wet as long as it is not sitting in water. I also think they are not so quick to dry out like peat pellets do. I started this tomato
on March 16 and today it is growing and blooming beautifully in my garden.
If you study this option on the internet, you’ll find lots of rules and do’s and don’ts. For instance there is talk of initial Ph level adjusting, lemon juice remedies, and some chat groups say you can’t transfer these into soil growth, etc. I didn’t do any of that and I did plant this tomato into the soil and had no problem at all. The only thing I did do prior to putting the seed into the cube is rinse it well in running water. If you are used to using peat pellets, I used the rock wool in the same way. I moistened it thoroughly first, inserted the seed, kept it moist but not soggy wet and waited for the seed to do its thing. I’ve used them on a heat mat or not, either way.
They cost a little more per each than peat pellets or coir pellets. I didn’t really shop around, I just went to my local hydroponics store for the sake of convenience and time so you may find better prices. If you are looking for peat free alternatives, I encourage you to experiment with rock wool cubes.
In Bloom in My Garden Today: Alyssum, Armeria pseudarmeria latifolia ‘joystick mix’, Asiatic lily, Baptisia, Begonia ‘bonfire’, Bletilla pink, blueberries, Carnation, Daisy(white double), Daphne caucasica, Digitalis grandiflora, Fuchsia, Gaillardia (blanket flower), Hardy Geranium, Heuchera, Hosta, Kniphofia ‘little maid’, Iris, Lavender, Lobelia, Mullen chaixii ‘Album’, Nepeta ‘six hills giant’ (catmint), Peas, Phygelius ‘new sensation’ (cape fushia), Rose, Salvia, Sedum, Thyme, Tomato, Veronica ‘royal candles’