March 18, 2004 at 3:28 p.m.
Since there were demonstrations on propagating and starting plants, I felt that this would be a good topic for this week.
A sure sign that spring is coming is seeing our houseplants putting out new growth. This signals that the time is good for taking slips or cuttings from your favorite plants. It is also time to take cuttings from geraniums and other plants you have overwintered indoors. Don’t plan to root them in water as the cuttings will often rot this way and the roots that do develop are soft and less sturdy. They tend to float rather grow downward as they would in soil. When you go to plant cuttings that were rooted in water, the roots will clump together when you remove the cutting from the water. Often, a cutting that looked perfectly healthy has trouble with this transition from water to soil, and you may lose it.
It is best to start houseplant cutting in clean sand, vermiculite or perlite. I based much of this article on the writings of Deb Brown, Extension Horticulturist at the University of Minnesota. She uses horticultural vermiculite, a naturally occurring mineral that has been heat treated to fluff out, a bit like popcorn. Water clings well to its many ridges. Vermiculite is light weight, clean and easy to handle, and may be purchased in bags like potting soil at nurseries and garden centers. There has been concern in the past about asbestos contamination in some vermiculite. The product available now is not thought to pose a health risk as long as you are not breathing the dust on a daily basis.
Take a 2" to 3" unglazed clay pot and plug the drainage hole in its bottom very tightly with modeling clay or a cork. Line the bottom of a 10" plastic pot with a paper towel and then fill with vermiculite. Push the clay pot down into the vermiculite twisting it back and forth until the top rim of the clay pot is level with the vermiculite. There should be a 3" wide ring of vermiculite around the clay pot. Moisten the vermiculite, then fill the clay pot with water. As the vermiculite dries, moisture will wick through the walls of the clay pot. Detailed instructions with pictures can be found on the web at: http://www.extension.umn.edu/distri bution/horticulture/components/DG4419.pdf
Now cut the stems to be rooted, insert them into the moist vermiculite, and put the whole assembly into a clear plastic bag. Fasten the top of the bag to keep the air around the cuttings humid. Set the pot in a warm place with bright indirect light. The clay pot is a water reservoir, so you will not need to water the cuttings as long as you keep it filled.
Most plants may be rooted from cuttings taken using stem portions that include two or three leaves. Start at the top of a stem and work your way back. Stem cuttings should be no more than four or five inches long. Remove the lowest leaf before sticking the stem in the moist rooting medium.
Roots should form at the node, or part of the stem where the leaf was attached as this is the area of rapidly dividing cells. You can also stick individual leaves without stems from African violets, peperomias, jade plants and other succulents directly into the rooting medium.
Cuttings from different plants will vary on how long they take to root. After a few weeks have passed, tug gently on the cuttings every so often. When you feel resistance you know that roots have formed. Scoop the cuttings out as they root, using a spoon or your fingers. Shake a little of the vermiculite off, then transplant the cutting into a small pot with fresh potting soil.
Fill the gap in your rooting pot with additional medium and water it. You can stick in a new cutting if you wish. Periodically you should wash the pots and fill with fresh vermiculite to prevent the build up of disease causing organisms.
Forms are still available to preorder bare root strawberry, raspberry, blueberry and grape plants. Many of these are cultivars developed at the University of Minnesota and used by commercial growers, but hard to find for home use. You can view the plant order form on the web at: http://www.extension.umn.edu/coun ty/Chisago Click on ‘fruit plant order form’ in the Hot Topics box. Master Gardeners will be at the Community Connections Expo, in North Branch, March 20 and at the Lindstrom Home and Garden Show March 27. In addition to taking orders for the bare root plants, they will be selling native plants and seeds for native and heirloom plants.