5 Ways Perennials Grow (and How to Divide Them)
Spring is finally here again, and I want to talk about one of my favorite gardening projects for this time of year: Dividing perennials!
The minute I see those tiny green sprouts pop up, I’m so excited because after babying my perennials all last season, they’ve now returned, matured, and have given back on their investment with luscious, thick new growth!
Then, after dividing them up, there’s all the fun to be had with your extras: spreading them far and wide around your yard, trading them at a local plant swap, sharing them with a friend, or even selling them!
However, if you’re new to dividing perennials, you may be a bit intimidated to dive into it, like I was when I first started.
The trick is….Know your perennials’ form of vegetative reproduction!
What is Vegetative Reproduction?
I feel like I'm giving my secrets away, because once you understand vegetative reproduction, you can grow almost any perennial!
Vegetative reproduction is the way a plant reproduces an exact clone of itself using roots, stems, and leaves as growing structures rather than seeds.
If you are careful to protect these growing structures while dividing, you can have new baby plants after having the original perennial, or “mother plant”, as I like to call it, in the ground for as little as one year.
If you can determine the type of vegetative growth your perennial exhibits, then you can determine how to go about dividing it.
Here are five of the most common types of vegetative growth you'll find in your garden.
1. Clump-forming
Clump-forming perennials generally stay in tight clusters that create new growth/roots that come up right alongside the previous year's growth.
Clump-forming perennials kind of look like a rose in their growth pattern: If you imagine the center petals of a rose as the original mother plant, then each ring of outward petals would be a new year's growth, and each petal represents a separate “baby” plant with its own roots.
You'll find that most of your perennials fall under this category. Some good examples you might find in your own yard are Hostas, Daylilies, Coneflowers, and even many types of ornamental grasses, like Miscanthus or Muhly Grass. They add new growth around the center plant that is fairly easy to separate because each new cluster has a pretty good establishment of its own roots.
Be careful not to damage the mother plant/other off-shoots too much when you're trying to break the new growth away. They are often so close together you can accidentally sever other babies at the growth point or snap them from their root base. If that occurs, then the division is lost!
2. Stoloniferous
Stoloniferous plants (or “Runners” as we gardeners sometimes call them) are often frustrating for gardeners because they can quickly become difficult to contain.
However, they are probably the easiest of all the plant types to divide. This is because the plant will send a long (or several long), fast-growing stems out from the mother plant that quickly form a new node/growth point that develops leaves and roots and becomes an entirely new self-sufficient plant.
This plant will then throw out its own runners as the cycle continues, and you can see where it becomes out of control rather quickly as it spreads from one end of your garden to the other in a short amount of time!
Some examples of these are Strawberries, most types of Mint, and your indoor Spider Plants.
As would be expected, all you have to do to divide these plants is cut off the runner stem once the new plant has formed. Remove it and ta-da! New plant.
Some creative ways I have heard to contain stoloniferous plants are: Raised beds (built up high enough that the stolon doesn't hop over the edge and find the ground below!), buried cinder block beds, planting in an area surrounded by things with more dense root growth (trees, plants with fibrous roots, etc), or planted in a planting strip bordering a non-permeable surface such as a sidewalk or road.
3. Rhizotomaceous
Rhizotomaceous perennials are plants that rely on a thick, fleshy underground stem (called a rhizome) to store energy and to build new offshoots of growth. Examples of these are Bearded Iris, Ginger, and your indoor-growing Snake Plants.
These are also easy to divide, because the fleshy underground rhizomes are usually “segmented” to make them easy to snap apart.
As you divide the rhizomes, it is generally best to discard the segment that had flowers the previous year, as rhizomes put their energy into creating a new segment that will have the fan of leaf growth and flower you are looking forward to the next year.
4. Bulbs/Corms
These are technically two different types of plant clone reproduction, but they are very similar in how they are divided, so I am lumping them together here.
Contrary to popular belief, bulbs and corms are not roots, though they are planted underground. They are both actually considered to be stems. This makes sense when you notice the typical-looking roots growing at the base of the bulb/corm during its active growing season.
The bulbs themselves store the energy that, after the appropriate soil temperature has been met, triggers leaf and flower growth up to the soil surface.
Examples of bulbs are fairly well-known: Daffodils, Tulips, and Hyacinths are some of the most familiar. Common corms are Gladiolas, Crocus, and Elephant Ears.
Corms and bulbs are fun to divide because a segment of the bulb will separate itself off and enlarge to become a new bulb.
I have found that with most of these newly separated bulbs/corms, it takes about 2-3 years before they will produce flowers. Therefore, while they produce leaf growth the first year they separate, I will watch them for the next two years or so before I dig them up to be planted on their own.
5. Tubers
Tubers are similar to bulbs and corms because they are also considered a fleshy, underground stem. Common tubers are potatoes, Dahlias, and Cassava/Yuca.
Tubers can vary a bit in their divisions: a potato can be literally cut up, and as long as you have a healthy “eye”, or growth point, you will potentially be able to grow a new plant. Just remember to allow the cuts to heal in a cool, dry place, usually over the winter months, before the calloused tuber can then be planted anew.
On a Dahlia, you will still look for the growth points/“eyes”, but they usually occur along the “neck” of a clump of their tubers. You then divide the neck where each potential new division will have intact eyes and tubers that will support the new vegetative growth, and in the late summer, the stunning Dahlia flowers!
If, after learning about each of these vegetative growth types, you are still concerned about cutting into your perennials, consider this last bit of encouragement: regularly dividing most of these types of perennials induces them to yield more flowers and healthier growth! When you get nervous about taking the plunge to pull them out of the ground and divide them, just remind yourself they like it better this way!
I just love dividing my perennials. I'm headed outside right now to get to it–maybe I'll see you at the next plant swap, and you can share your favorite plant with me!