Fall propagation is such a fun task, especially with the winter cold around the corner. As you’re shutting the garden down and cleaning it up for autumn, you can turn your attention to which plants deserve a second life. And there are multiple ways to propagate, each with its own benefits.

If you live in a region where the fall is mild and frost isn’t on your doorstep, you can propagate and get plants in the ground before fall ends. If you live somewhere cold, it’s time to prepare a space sheltered from the heavy frost that prompts plants to enter dormancy.

Knowing which propagation method is best suited to which plants is an important distinction to learn before you get started. You can propagate cuttings, divide perennials, harvest seeds, and even layer. But you should tailor the method you use to the specific plant and site you’re working with.

Purple Coneflower Echinacea

Purple Coneflower Echinacea Seeds

Rocky Mountain Blue Penstemon

Rocky Mountain Blue Penstemon Seeds

Colorado Blend Yarrow Seeds

Know Your Environment

Your climate will determine what you can propagate now.

Start by locating your USDA hardiness zone and determining your first frost date. This is your baseline that helps you when you’re deciding which fall propagation technique you’re going for. Both help you determine how cold it typically gets in your region, and when it’s going to freeze.  

If you have just over a month before the frost arrives, outdoor propagation is possible. If frost is coming soon, you could set up a sheltered area indoors, or propagate under a cold frame outdoors. A greenhouse or garage is a great option, too. Understanding the microclimates of your garden, including those that tend to take on frost sooner, is important. 

Then think about the plants you want to propagate. Note if they tend to be woody, or green and supple. Are they annual or perennial? Are they root hardy through winter, or do they die and require replanting every year? As you think about these questions, make notes to keep things organized as you get your fall garden tasks together. 

Divide Perennials

The easiest fall propagation method is dividing overgrown perennials.

Perennial plants (meaning those that survive winter for multiple years) need fall propagation by division every year or so. Therefore, this is a good time to dig them up and split them for planting elsewhere.

Not all perennials need this, but those that have shown reduced vigor due to overcrowding benefit greatly. 

You’ll need a hand trowel or hori hori knife for smaller plants, and a large shovel for more sizable ones. Using the appropriate tool, dig outside the perimeter of the plant’s root system, and unearth the root mass. 

Dust the soil off the roots, and locate areas where separate masses are present. These should have above-ground growth attached to them. Gently pry them apart or cut them with your shovel or hori hori. Pot up your divisions or plant them in a new location in the garden. 

Here are a few perennials that benefit from fall propagation. Note that colder climate growers should decide if there is enough time for divisions to be planted in the ground. In areas where there are fewer than 4 weeks of frost-free weather, pot up the divisions and shelter them until the soil warms enough in spring.

• Aster
• Chrysanthemum
• Penstemon (beardtongue)
• Phlox paniculata (tall garden phlox)
• Achillea spp. (yarrow)
• Coreopsis
• Tiarella spp. (foamflower)
• Astilbe
• Liatris spp. (blazing star)
• Rudbeckia spp. (black-eyed Susan)
• Echinacea spp. (coneflower)
• Nepeta spp. (catmint/catnip)
• Geranium
• Hosta

Harvest Seeds

Collect seeds toward the end of the season to grow new plants.

Now is a great time for fall propagation by seed. Collect seeds from both annuals that don’t survive frost, and perennials that tend to self-seed freely and overcrowd. Remove ripened seed heads and collect the seeds to sow new plants. 

If you are working with seeds that need cold stratification, you can sow them in the garden right away. Those that don’t need a cold period should be sown after the last frost as soil temperatures rise enough to support their germination. Each plant is different, so ensure you know the best timing before sowing.

For annuals that need warmth to grow, you can start them indoors. Check out a growing guide to figure out the best time for sowing for the plant you’re growing. Be sure to have your seed starting gear at the ready, or winter sow them. 

Gather Cuttings

Remove woody cuttings from healthy plants now.

Many woody and herbaceous perennials easily reproduce via cuttings. As you’re collecting seeds for fall propagation, harvest some cuttings too. If you’re dealing with a mild fall, you can set your cuttings in bright, indirect sunlight outdoors. In cold climates, keep them inside.

Before you gather cuttings, do some research. Determine if the stems you’re propagating need to be woody or green. Also note whether or not the plant flowers on the current or the new year’s growth. This will tell you whether or not to expect blooms in the coming spring or the following one.

If you’re propagating cuttings in soil, a bit of rooting hormone helps. Once the plant roots, plant it in a container to shelter for winter, or plant it out into the garden.

In water propagation, care for your cuttings by changing the water out every day or so before planting in a container or their final growing place. 

Mound Layer Perennials 

Try layering for low-lying plants.

Layering is an interesting fall propagation technique that is good for some, but not every plant. But if you are working with shrubs and low-lying plants that tend to reproduce this way naturally, it’s a great option. It is especially useful for those that form adventitious roots on their stems.

Find a stem that is long enough to touch the ground with a few inches that can stick above the soil. Remove all the leaves from the area that will be on the soil surface. Then pin the stem down with a rock or landscaping staple and cover it with soil. Over time, roots form in the soil mound. 

Once roots develop, snip the part still attached to the mother plant. Then gently dig up the layered plant, and pot it up or plant it elsewhere. Because this is happening in place, it’s best to carry it out before frost, as plants enter dormancy and don’t actively grow during that time.

Air Layer 

Propagate trees or shrubs using this technique.

Fall propagation is possible via air layering, too. Instead of pinning a piece of a tree or shrub to the earth to form roots, you can use a layering pod or create a little pocket of compost with peat moss wrapped in plastic to promote root development. Look for stems that are one to two years old. 

You want to cut into the stem or peel up the bark, apply rooting hormone, and then cover with your propagation pod (whether homemade or professionally designed). Wait for roots to develop over the course of a year, then remove it from the branch when roots form.

Use black plastic rather than clear plastic to prevent algae development that will deprive the roots of vital nutrients. Once you’ve rooted and removed the stem, plant away, whether for sheltering in winter or out in the garden to root before the frost arrives.