Making new shrubs

The steps to propagate rose cuttings with a plastic bottle greenhouse.

By Shauna Dobbie

Years ago, when my nephew was very young, he went on a nature walk with my parents. He collected a stick along the way, as young boys do, and when they got to my parents’ place, he stuck it in the ground. The stick was from a willow, and without any coaxing it turned into a tree. Willows will root very easily. Graeme didn’t know that and thought it was a magic tree.

If only our hydrangeas and lilacs were magic trees. But they aren’t so difficult to propagate if you know what to do. In fact, you can increase your stock of many shrubs in reasonably short order.

The trick is rooting hormone. Willows already have it in abundance, which is fine for rooting willows, what about other plants? Fortunately, you can buy it.

To propagate most deciduous (no leaves in winter) shrubs: 1. Take a cutting. 2. Trim it down. 3. Dip the bottom in rooting hormone. 4. Plant in a pot. 5. Cover with a clear plastic bag, not touching the plant. 6. Take the bag off every couple of weeks to see if the plant has rooted. 7. When it’s rooted, take the bag off completely. Continue with the potted plant until it’s big enough to plant in the ground. This could be a few years.

Sounds simple. Actually doing it, though, you’ll have questions, which are hopefully answered in the rest of this article.

Take cuttings

Cuttings should be made early in the day. Cut just behind the leaf node in the softwood of the shrub. Softwood is neither brand-new growth nor truly woody growth; it’s in between. The growth is too new if it just bends. It’s too old if it won’t bend at all. If it bends a little, that’s about right. (Check out the video through the QR code above.)

Take a few cuttings. Even if you do everything right, don’t expect more than 70 per cent success. Some species of shrubs do better, some worse, others won’t be propagated from softwood cuttings at all.

Wrap the cut end in damp paper towel and keep the sun off of them.

Trim them

Make sure the cut is about one centimetre behind the leaf node; in other words, the leaf node is still on the stem. You can lightly peel off a couple of strips of bark from below the node with your secateurs, but you don’t have to.

Strip off the leaves from the bottom node. Then go up to the next set of leaves and cut just beyond them. Remove all but one leaf.

Dip in rooting hormone

Put a bit of rooting hormone into a small bowl. If the plant turns out to be diseased, you don’t want the rooting hormone to pass it on to future plants, so don’t dip the cutting into your whole container of rooting hormone.

Dip the bottom of the cutting into rooting hormone up to and including the bumps of the leaf node. Tap the cutting to release any excess. You don’t want too much and you don’t want too little; either will prevent development of roots.

Plant in a pot

Use a light mixture appropriate for starting seeds. You can plant the cuttings into cell packs, one per cell, or you can plant about three into a four-inch pot. Plant the cuttings so that the leaf is just above the soil.

Then water the pot or pots.

Cover

Cover the pot with clear plastic but without touching the cuttings. Put the pot into a spot with indirect sunlight, in a place where you won’t need to move it often.

Hydrangeas.

Forsythia.

Check

Every two or three weeks, take the bag off and inspect the cuttings. If they’ve gone brown or mouldy, they might be done for. Check for roots; it may be that the plant has rooted already. If they are mouldy and there are no roots, try again with new cuttings.

If they show new growth above the soil, they might not grow roots. The cutting is a plant under stress and it probably can’t grow new leaves and put out roots at the same time. If it’s early in the process, remove the new growth and check for roots. Later in the process, it might have already rooted well and is putting forth new growth. (Check for roots.)

To check for roots, lightly tug on the cutting. If it comes right out, look for any signs of roots growing from the leaf node. Don’t be discouraged if there are none; this process can take three or more months, depending on the species.

If you meet some resistance when you tug the cutting, there are probably roots. If you want to be sure, dump the contents of the pot out and have a closer look.

If there are no roots, put the cutting back. If the planting medium needs water, water it. Put the bag back for a couple more weeks.

If you do have roots? Command your family to refer to you henceforth as the propagation god, for you have succeeded. Take the bag off and continue to care for the plant.

Other cuttings

The directions here are for softwood and semi-hardwood cuttings. It works well on non-woody perennials too. It is also possible to propagate from hardwood cuttings, though it is a little more involved.

Most flowering shrubs can be propagated this way, including hydrangeas, roses, lilacs, forsythias, viburnums and spireas. If you aren’t sure about the ease of propagating your shrub through cuttings, you can either give it a try or look it up on the Internet.

Good luck!

Rooting hormones

The two natural rooting hormones are Indole-3-acetic acid (IAA) and Indole-3-butyric acid (IBA). There is also a human made hormone, alpha-Napthalene acetic acid (NAA) that plants cannot distinguish from IAA.

When you buy rooting hormones, look for either IBA or NAA in the list of ingredients. IAA isn’t used because it breaks down rapidly when exposed to light.

There are many sources on the Internet that claim you can make your own rooting hormone out of honey or apple cider vinegar or cinnamon. These items are antibacterial and can help prevent pathogens from growing on a cutting, but they won’t promote root growth.

There are also claims that aspirin or willow water will stimulate rooting. Either might help a tiny bit, but not to the extent that rooting hormone will. If you are serious about propagating shrubs, a little jar of rooting hormone is not expensive and will last for years; just buy it.