The basics of propagating plants in the Tucson desert

If you want to have more plants there are several ways to go about it. The first is, of course, to purchase and plant seeds. Seeds are the product of a plant’s sexual reproduction. They are usually quite inexpensive, but may not have high germination rates. Even once seeds germinate, it can take a while to nurse them into a full-sized plant.

However, you can also propagate plants asexually — that is, without mixing DNA of different plants. Essentially what you get this way is a clone of your previous plant. This can be a good thing for several reasons. For one thing, you start out with something that looks like a plant (or part of one) and it may take less time to get a fully-grown plant. If you particularly like the characteristics of a certain plant you grow, a clone will have those same characteristics. Also, many of the plant propagation techniques are pretty easy to master, and will provide you with an opportunity to multiply your plants at little cost. Finally, plant propagation allows you to grow lots of plants to share with friends and family.

This article just covers the basics. For more details, take a look at this detailed guide to plant propagation. If you want to know about propagating a particular plant, it’s best to do an internet search for that plant. Most gardener resources will let you know how it can be propagated. Garden Oracle has some great information on plants in our area and always includes the type of propagation the plant is capable of.

This method works well for herbaceous (non-woody) perennials. You can also do it with some woody shrubs — roses are a classic example — but only when they’re dormant. Division is pretty much what it sounds like — if you have a big clump of a plant, you dig up and separate out a small section, trim off the old stems, leaving the newer ones, and replant it elsewhere. The new small plant already has its own roots, so should take less time to get established than a plant grown from seed or from a cutting. Spring-flowering plants can be divided in the fall, and summer-flowering plants can be divided when dormant in the early spring. You can try this with some herbaceous perennial desert flowering shrubs like evening primrose (Oenothera speciosa).

This is where you cut off a plant part and put it into soil so it can develop roots. You can take cuttings from stems, leaves, or budding areas of the plant. Depending on the plant you are using and the type of cutting, it may take a few months for the plant to start growing on its own. If you’re taking leaf cuttings, the best time is late summer; for softwood stems, take cuttings in the early spring; and for hardwood stems, the best time is in winter when they are dormant. Houseplant cuttings can be done just about any time.

Some plants (for instance houseplants) may also be put into water in a glass container. You can see the roots developing over time, and then transplant the plant into soil once it has a few well-formed roots. It’s also a fun project to do with kids, so they can see how roots develop.

To take cuttings, you will need a sharp cutting tool and some rooting hormone powder. Slice off the plant part (stem or leaf), dip the stem into rooting hormone powder, and plant in the soil. You should keep the soil moist and warm to encourage root growth.

Here’s a video with step-by-step instructions on propagating with cuttings.

With the layering technique, you are trying to get a plant to grow roots from a branch while the branch is still attached to the plant. It’s very easy and low-effort. This would be good to try with woody shrubs, like Tecoma spp. which tend to have thin branches low to the ground. Layering should be done in early spring.

You take a low branch and bury part of it in the ground, making sure that the end with the shoot is sticking up out of the soil. You can stake up this end so that it grows straight. You can cut a small wound in the stem that’s buried in the soil — some think that it may root faster that way. Make sure you keep the soil moist.

Once the new plant has rooted, you can cut its connection to the parent plant. The disadvantage to this method is you end up with a plant right next to the parent plant, so you will need to transplant it to where you want it, which is an additional stress for the plant.

You can also do layering with longer vines, alternately burying multiple loops of the vine. This is called compound or serpentine layering. There is also a technique called air layering, where the cut is made partway up a stem and covered over with rooting hormone powder, sphagnum moss and plastic and kept moist until roots develop. If you’re willing to try this, I commend you; I think it would be a challenge to make this work in our dry climate.

If you’ve ever eaten any kind of fruit, you can thank grafting, which allows gardeners and food growers to join two plants with different characteristics together. The advantage of this is that you can have a root stock that has desirable qualities such as disease resistance, drought tolerance, and hardiness with a different variety of plant on top (called the scion) that produces the type of fruit, flowers or foliage you want.

This is particularly important for fruit trees, many of which don’t produce seeds that grow true to seed.  For example, a Golden Delicious apple will produce seeds, but if you plant those you won’t get trees that grow Golden Delicious apples — you’ll get a bunch of different weird apple trees, many of which you may not want.

Some adventurous gardeners (particularly if they have limited space) graft multiple different scions to the same rootstock, thus having one tree that produces multiple fruit varieties. You will need plants of the same species; although you can graft together two different species, the results are generally poor.

Grafting is usually done in late winter or early spring before growth restarts. It’s a fairly complex process, and the full description of grafting is beyond the scope of this article, but in brief, you cut both the scion and the root stock at an angle (there are special tools for this), cover the joint with grafting wax to keep it from drying out, and wrap the two together using grafting tape. The plants generally heal together within a few weeks. You can read a full description of the process along with helpful diagrams in this article on grafting from the University of Missouri.