I’m picking 2 pints every other day from my 3 old blueberry bushes and another pint from a couple of their offspring rooted in 2010 and planted last year. Blueberries and other woody plants put on lots of new growth most years and so can have hard, soft, and semi-hard wood on the plant at the same time. That makes it both harder and easier to decide when to take cuttings, and indeed, there are 2 times worth considering. One opportunity, hardwood cuttings, has passed for this year, but the other, soft-er wood cuttings, is ready for your mist chamber. Yes, a mist chamber, which is easier to do than you may think and valuable for rooting lots of reluctant cuttings.
What I call soft-er wood is not the newest growth, but neither is it classically semi-hard. Once the new growth comes on and the leaves are fully expanded, it will be about a month before it is firm enough to use. Because they are still relatively tender, blueberry cuttings can wilt and so need mist while rooting. Blueberry and similar cuttings need to retain their leaves in the process, but the cut stems cannot take up enough water to hydrate them and root at the same time. A few seconds of mist at regular intervals allows leaves to retain the water they would otherwise lose to transpiration. Those who have greenhouses can devote a part of a bench or use the space under a bench to create a rooting box with an intermittent mist system. Timed mist provides a burst of fine droplets to raise humidity levels and introduce moisture to the cuttings, most often inside a plastic drape. If you use smaller propagation hoop houses, it is usually necessary to provide mist to the entire structure to control temperature. Self-contained, commercial mist systems can be pricey, but their elements are not. With a basic understanding of how they work, you can customize a system for your space. Check out this good how-to article that will guide you to build a propagation mist system: http://www.ehow.com/how_5721112_build-plant-propagation-mist-system.html.
I want to be clear – soft-er wood blueberry cuttings can be a bit tricky to get going and the usual success rate is about 80% for experienced propagators. If you want 10 plants, stick 15-20 cuttings for insurance. True soft wood cuttings will be damaged as you stick them into the rooting media and crushed tissue collapses quickly. True semi-hard wood is stiff in comparison. You are seeking the in-between wood and like so many things, once you see it, you know it. Take 6” cuttings from the tips of blueberry stems and remove the leaves from the lower half. Leaves inserted into rooting media will rot and can keep conditions wet and worse, introduce fungus. Use the medium of your choice – I like a soilless mix with a bit of perlite added for woody plants. Don’t scrimp on the pot size for woody cuttings. Since at least 3 inches of stem will be in the soil, provide 3 more inches below so water does not saturate the mix and soak the cutting. In a practical sense, this means you can use a deep quart sized pot for each cutting or a regular one gallon shrub container for 3 or 4. Roll the tip of the cutting (you did cut it on a slant, didn’t you, to increase surface area?) in Hormex #8 and stick it into damp mix. Put the pots under mist and water as needed to keep the mix moist but never super wet. When you do irrigate, add 1 t of Hormex Liquid Concentrate to each quart of water.
If you are interested in hydroponic blueberry propagation, explore this article about
a mist system for propagating blueberry plants: http://www.ehow.com/how_12134664_make-mist-system-propagating-blueberry-plants.html. Some growers prefer to use this method because it reduces the chances of encountering fungal infection in the soil used for rooting and because it is very efficient. I have not built this one, but it works like the commercial types and would be intriguing to try out.
Just one more note, about plants that are patented. These plants are usually new to the market, after years of trials done to be sure they are better than existing choices. To protect the expensive research done to develop the variety, a patent is issued and propagators shell out big bucks for licensing rights plus a fee per plant for the right to grow them. Non-licensees (like you and me) are not allowed to propagate patented plants for profit and sometimes not even for personal use. Check your varieties and be sure they are not restricted before you root them. While prosecution may seem unlikely, there is an ethical issue here. Simply put, it’s stealing and you shouldn’t do it.