Nusery Notes: Growing cuttings made simple

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In the greenhouse this week, we hit the halfway mark for the seeding, 100 flats of 300 seeds each. That is down some from recent years but we are doing more propagation by cuttings than ever before. You can grow most everything by cuttings, from softwood geranium cuttings to hardwood (dormant) cuttings of grapevines. Some plants are best done at the end of summer but for the most part now is a really good time to take cuttings of those geraniums you overwintered in your basement window, perhaps your favorite grapevine.

What will you need? You should collect some healthy plant material, a sharp knife, rooting hormone, rooting media, a misting bottle and some clean clear plastic. If your plants are actively growing, give them a good shot of water and some plant food. Try 20-20-20 at one or two grams per litre. The next day, the cells of your stock plant will be full of extra moisture.

Take a sharp knife and make a clean cut through the stem, preferably at a leaf node. I use a 45-degree angle cut on the portion of a stem that is to grow down, or a flat cut on the top of a cutting in situations where more than one cutting is being taken from one piece of stem, as in a grapevine. This ensures that what is meant to grow downwards will end up in the rooting media. We call this observing polarity. By cutting through the leaf node, your cuttings will root twice as fast than if they had been cut through the internodal portion of the stem. The reason has to do with cell division.

A rooting powder will also help encourage rooting. Lots of plants don’t really need the help but to be on the safe side use No. 1 powder for softwood cuttings (geraniums and the like) and a No. 3 powder for hardwood (dormant) cuttings like your dormant grapevine.

Place the cuttings with the angle cut down into the rooting powder and tap off the excess. Then place them firmly into the sterile rooting media like potting soil, perlite or a Jiffy 7 peat pellet. Increase the humidity around the cuttings by placing them inside a clear plastic bag or a mini-greenhouse.

Mist frequently but allow the leaf to dry between applications. In the “prop” greenhouse this is automated by the use of an electronic misting leaf. It is basically a piece of wire mesh counter balanced with a small weight to activate an electronic solenoid on and off. As the leaf dries off, it gets lighter and rises. This activates a pulse of mist, which as the wire leaf gets re-wetted and heavier, drops lower and turns the water off again.

As with seed propagation, the application of bottom heat — that is. a warm root zone — aids in cell division. This increases the speed of root growth. Keep the top part of the plant cool. This reduces stress on the cutting and gives a better chance for the cutting to root before drying out.

Some pointers on the grapevine propagation: use pencil-thick wood about 16 inches long, observe correct polarity, angle cut through a node at the bottom and push half the cutting in the rooting media.

Cold soil will slow the process but lots of people have good success rooting grapes outside in a bucket of moist sand. Inside with your geranium cuttings, they could have roots in as little as seven-10 days or as long as a month. With the nursery set to open this weekend, I have to keep this column short and sweet. Have fun!

Evan and Wendy Davies own Beltane Nursery at 2915 Highway 3 in Erickson.