Free plants? Yes please! Propagating plants by division splits an existing plant into two or more segments to be replanted as new separate plants. Sweet! Here’s an introduction to dividing suitable plants from your home garden.
What Types of Plants Can be Divided?
Division is most common with mature herbaceous perennials. It can also be used with suckering plants, offsets, and bulbs (what I call lazy lifting).
Large Clumping Perennials
Division is a go-to method for splitting large clumping or creeping herbaceous perennial plants. For a plant to be propagated through division, it must have multiple stems growing from the ground. Each divided clump needs both roots and stems (or a portion of the crown which will grow stems).
Runners and Stolons
Smaller plants and shrubs that naturally send out runners or stolons, such as strawberries, raspberries, and blackberries, are one of the simplest forms of plant to propagate through division. The picture above is a strawberry runner after being divided and replanted. Runners are horizontal stems that grow above ground from the crown. Little baby plantlets set along nodes on the runners and grow their own roots, from which a new plant matures.
Offsets
Plants that grow hen-and-chick offsets, like many succulents, can also be divided. They have a lateral stem umbilical from the parent plant (hen) that grows an adjoining offset (chick). It’s similar to a runner, but much closer to the parent. When offsets are well rooted, they can be treated similarly to runners and stolons for division and replanting. If they are rootless pups, you may need to treat them like a succulent cutting instead. I like to allow my succulent cuttings some drying time prior to rooting.
Bulbs and Bulblets vs. Tubers and Rhizomes
Similarly, bulbs that clump with new bulblet plants developing around the original bulb parent plant are also easy candidates for division. They’re naturally well-suited to separation. Dividing and propagating bulbs may be done carefully during growth if needed, or saved for safer lifting and separation during dormancy.
Tubers and rhizomes are a little trickier. As noted in our post about propagating bulbs, these are technically big fat fleshy underground stems rather than true bulbs. When dividing the plant, these may need to be cut apart into sections with a sharp clean knife or pruners. The ease of propagating varies greatly with plant variety.
Propagating Garden Plants by Division
When to Divide and Propagate Plants
You can divide plants at any time (growing conditions permitting); however, the best opportunity is usually when the plant is not in active growth. Spring and autumn are the most common times for division propagation. Since root disturbance is much lower, there’s greater leeway for timing on modified division. For example, separating runners and stolons from their parent plants can happen on an opportunity basis, if needed.
Dividing Plants
Each section of the divided plant must include both roots and crown (or shoots/leaves for suckers, chicks, and other variants).
- Rough division cuts and digs out a large plant in smaller clumps that are then immediately replanted. The best tools and techniques will depend on the size and sturdiness of the plant. With bigger specimens, it’s not uncommon for this to involve large digging forks, a spade tipped shovel, or even an axe!
- Fine division lifts the plant first for a slightly more selective splitting of the parent plant into smaller clumps. This may involve teasing the plant apart into sections, careful cutting, or a combination of both. If the plant has a woody crown or fibrous roots, some cutting will usually be needed.
If you wish to preserve the size of the parent plant, you can sometimes take small divisions from the edge of the donor parent by splitting them from the parent in-situ using a sharp spade or similar.
When you are dividing a mature perennial with a “spent” core in the parent plant, the middle pieces may be nonviable. If that’s the case, they can be discarded to compost instead of replanting. No harm in trying if you wish, though. Admittedly, I hate to throw out a possible plant. You can always pull and compost later if they fail to survive or thrive (see troubleshooting below).
Replanting Divided Plants
When planting, the aspect, depth, and other environmental conditions should be well-suited to the type of plant you’re propagating. Prepare your planting area before division if possible so that you can minimise stresses on your plants by replanting as quickly as possible. If immediate replanting isn’t feasible, such as plant sharing or garden works, protect the plants with interim measures as you would any transplant. Of particular importance, don’t let the root ball (or split root balls) dry out during the process. For the short term, wrap the roots until you can replant. For lengthy delays, you may wish to pot the plants into temporary containers.
Reducing Transplant Shock During Division
Transplant shock prevention techniques need to be modified for division. With the exception of modified divisions (runners, chicks, etc.) root disturbance is essential to the separation process of splitting the plant. While many plants cope very well with rough handling for division, the less damage done in removal and division the lower the stress. It’s tempting to create more plants, but larger divisions with ample healthy roots can have better chances of survival.
With the exception of the root issue above, you can use similar techniques for transplant shock as you would for whole plants. Water thoroughly after planting and don’t let the new plantings dry out during re-establishment. If the plant you are dividing has ample foliage at the time of separation, it may be beneficial to prune some of the foliage or cut back the leaves by up to two thirds. This can help protect the plant from water losses and encourage the plant to focus on its root system during re-establishment. If you’re a fan of seaweed solution, sugar water, or other tonics, you can try those as well. I use seaweed solution on my new plantings and transplants.
Plant Care
Once re-established, plant care is the same as the parent plant. Of note, plants that can be propagated through division often benefit from the process of being split every few years. Win win!
Division Troubleshooting Tips
Divided plants are essentially transplants that get roughed up and split into pieces during the process. This means that although it’s a very easy form of propagation, it doesn’t always end in success. Transplant shock and other difficulties may be encountered with divided plants.
Divided Plants Don’t Survive After Replanting
If your divided plants don’t survive propagation, review your garden journal notes on plantings. Double-check that the varieties you’ve chosen are well-suited to propagation through division and to their new planting conditions in your garden.
If everything looks good on paper, but the plants haven’t thrived, consider whether there have been any adverse conditions during propagation or settle-in that may have compromised the plantings. Were there any difficulties during division? Did you have trouble digging out the root ball or separating the plants? Did the clumps have enough healthy roots? Was there any difficulty splitting the crown? Were there any delays in replanting or harsh weather, like an unexpected freeze or stretch of hot dry weather while your plants were settling in to their new positions? It’s tempting (so tempting) to overdue splitting in the hopes of maximising the new plants, but larger divisions with ample healthy roots can have better chances of survival, especially if you are autumn propagating before a harsh winter or out-of-season due to other garden works.
Sometimes, no matter how carefully we divide (or plant in general), things just don’t go to plan and the plants may not make it. If you aren’t sure what went wrong, don’t fret too much. Successes and failures are all part of gardening.
Divided Plants Survive but Fail to Thrive
If new plantings survive, but fail to thrive and there are no obvious issues with variety, pests, or disease, it may be due to adverse conditions during propagation or settle-in (see above). In which case, they will hopefully perk up in time. Alternatively, they may be suffering from other adverse growing conditions in their new home (poor variety for location, low quality soil, poor aspect, over shading, etc.). Double check your growing conditions, adjust if needed, and see how things go with time.
Divided Plants Growing Well but Not Flowering
If new plantings grow well but fail to impress with blooms and there are no obvious issues with variety, pests, or disease, don’t panic just yet. It is not uncommon for divided plants to leaf well but flower poorly in their first year. The divided plants may be busy putting energy into root development and re-growth. If this doesn’t improve in the next growing cycle, revisit your growing conditions to see if there may be issues with soil quality, shading, etc.
Established Plants Declining in Vigour
If divided plants were initially performing well but are declining over the years, decreasing soil quality, increasing shade from nearby maturing plantings, or overcrowding may be factors. Some plants benefit greatly if they are divided periodically, as noted above.
