More Media Notes
Choosing a rooting medium is an important step best taken with your ultimate goal in mind – a healthy plant suited for your growing style. Most plants that we root are intended to be moved into larger pots and space for rooting them is often at a premium. Some rooted cuttings are made for hydroponic gardening systems so are best started without any soil at all. These realities have spawned clever products that allow strong roots to develop efficiently in small spaces and without soil. You can purchase or make your own rooting cubes from a variety of materials.
A disclaimer here – I did not have children until I was over 30 years old and today they refer to everything about my life before they arrived as ancient history, or Old Mama. Therefore, Old Mama and other dinosaurs once had to cut or punch out small squares of florists’ oasis to make cubes for rooting. It was time-consuming to do all that carving and the oasis shattered too often in the process. As a result, the ‘cubes’ varied in size and the least perfect shapes got crammed into cells and flats instead of being neatly arrayed. Such variance does not just look messy; it can be a challenge to keep the different sizes watered evenly. Mechanical punches helped with the sizing, but still it took time to perfect enough cubes for large projects. These days, you will find neat oasis and other foam cubes and sheets that are sold in custom-sized flats, ready to wet and stick with as many cuttings as you have room to root. If you are short on space, remember that you can always put more squared shapes into a space than similar sized round ones.
Bark starter cubes have many of the same qualities that pots of finely ground bark do, and will produce similar stocky roots. I find them useful for rooting small caliper woody stems and some succulents. Both need to dry out more than other cuttings to prevent rot, and bark works for them.
Oasis cubes make a good rooting media for green plants and some woody ones, and, like rock wool flats, is very desirable if you are growing in a hydroponic system without soil. Yes, you can wash roots of seedlings produced in soil before adding them to the system, but oasis and rock wool produce cleaner roots that are far less likely to pollute it. Water these materials and use a clean tool to poke a starter hole for each cutting. Although I am an inveterate recycler, these are not products to reuse and must be discarded to avoid contamination.
There is usually more than one way to root any particular plant, but maintaining a variety of different rooting media plus pots, flats, and cubes can be daunting. Gardeners often settle on one or two methods that make sense for their plants and their growing conditions. I am often rooting cuttings of some plants while starting seeds for others and have developed a way to do both right next to each other on the bench, which is actually an old dresser. No, it doesn’t work all the time for everything, but my percentages are good. Here’s how I do it: Fill flats or small cells with a soilless, fine-textured media such as Metro Mix and water them thoroughly. On the bench, roll out a heating mat made for propagation. On top of that, put a plastic tray that is at least an inch deep and nestle the flats of rooting media into the tray. I dip the base of each cutting into a little bowl of full strength Hormex liquid concentrate before inserting it into the media. This setup lets me provide bottom heat and water the flats from the bottom by filling the tray. I use plastic boxes with vents on top of the flats to keep humidity levels up around both cuttings and seedlings. A grow light fixture with energy efficient, full spectrum bulbs on a timer hangs over the setup. It’s the perfect light for the plants, but also for fighting the winter blues and blahs that come with gray days. And the cats like it, often dozing on the daybed in the same room in the glow of my propagation dresser.