Weigela shrub, ready for stem cuttings
Plant propagation is just a fancy word for making more plants from what you have. I love to propagate the plants in my garden. To me it is magical that an entire shrub can be created from cutting six inches off the stem. Taking stem cuttings is an easy way to make more shrubs to fill in gaps in the garden or to share plants with gardening friends.
Summer is a good time to take “softwood” stem cuttings of shrubs. The term “softwood” relates to the time of year the cutting is done — usually May through July. This is the point where a deciduous shrub’s new spring growth starts to become semi-woody but still supple enough to root easily. The shrub’s stem must have new growth but be firm enough to snap. If you can grasp the end of the branch about 6 inches from the top, bend it at a 90-degree angle and it snaps and breaks off, it is ready. Depending on the plant and your comfort zone, it may not be necessary to use a rooting hormone.
The best time to take cuttings is in the early morning when the plant is turgid, not wilted from the day’s heat. Cut from the tip of stem, about 5-6 inches down, ensuring that there are several nodes. The node is the point where additional stems/branches arise but also the point in which there is a higher chance of roots stimulation. First cut above the node on the shrub and then make a second cut on the stem, just under the last node. Remove the bottom leaves and insert the cutting into water, then a rooting hormone (if going to use one), and then in the pre-moistened potting mix, about one-inch deep.
stem cutting of a weigela shrub
For small shrubs, use a small plastic container and cover the plant with a gallon size Ziploc plastic bag. Blow air into the bag to inflate it as much as possible and close it. Write the plant name on the bag and write down the plant name and date on the calendar or gardening journal.
For large shrubs, such as an oak leaf hydrangea, use an old glass fishbowl, covered, or the large plastic containers of Twizzlers.
Place cuttings in a cardboard box in the shade (the box prevents the bags from blowing over or away). Check the bags to make sure condensation developed inside. If there is condensation, it has enough moisture. If there is no condensation, open the bag, take the plastic container out, water, and put back in the bag.
It may take a few weeks to a few months for the stem cuttings to root. Check by opening a bag and gently pulling the cutting to see if there is resistance. If the cutting has rooted, start to open the bag a little bit, a few hours a day, still in the shade. If the plant wilts very quickly, it has not produced enough roots yet. Successful rooters will keep their color in their leaves; unsuccessful plants will fade or collapse.
weigela cutting in an inflated bag
Once the plant can survive outside the bag, move to a larger container. Gradually expose the plant to full sun. You may end up planting it in the garden bed in the fall because the larger the plant, the more the roots and the more likely it will survive. Plus, cool fall weather is better for transplanting than hot summer heat.
If the plant is a quick and easy rooter, you will not need a commercially prepared rooting hormone. Plants have hormones that aid in the formation of roots called auxins. The amount of auxins may vary in plants throughout the year and within the plant. If you do not know if it will root easily or you want to increase your chances of a quick root, you can use a commercially prepared rooting hormone. In other words, it does not hurt to use a hormone. Commercially prepared rooting hormones are comprised of synthetic auxins called indolebutyric acid and/or naphthaleneacetic acid. Usually a lower percentage of the synthetic hormone is required for these softwood cuttings (1,000 ppm or .1 percent) and often comes in a white powder form. When you use the rooting hormone, put a small amount in a little container to prevent contamination that could occur if you dip the stem cutting into the original container.
Dipping stem into small amount of rooting hormone
When you are multiplying by stem cuttings you need to prevent fungal growth. Use clean plastic containers with drainage holes and bagged potting mix (not ground soil). Use tap water for watering the potting mix and for moistening the cut before dipping in the rooting hormone. Bags, including the larger propagation chambers such as plastic shoe boxes, plastic storage containers, Twizzler containers, and glass terrarium/fish tanks, must be clean.
This month, try taking several cuttings from one shrub so if one does not root, you won’t get disappointed. Experiment, take notes, and discover the magic of plant propagation. Good luck!