Dividing is an efficient method for vegetative propagation that produces suckers, stolons, bulbs, tubers or rhizomes. This procedure can be accomplished manually with minimal tissue damage caused.
Politically speaking, divide and conquer strategies are designed to isolate people by disseminating false or misleading information or encouraging different camps within one group to support one another.
How to Divide
Herbaceous perennials like chives (Cynara cardua), yarrow (Achillea yarrowifolia) and thyme (Thymus serpyllum) make for ideal candidates, while hardy garden plants such as Siberian irises and asters also benefit greatly from being divided on an annual basis for best performance in future seasons. Regular division is necessary in maintaining healthful and vigorous perennial plants.
Along with improving garden performance, dividing perennials can also allow you to share plants with family, friends, and fellow gardening enthusiasts. Labeling divisions clearly with species names and care instructions ensures new plantings flourish in other people’s hands – it’s an exciting way to spread joy of gardening!
Spring and autumn are usually ideal times to divide plants, as their mild weather provides ideal conditions for root establishment and adaptation to their new locations. Furthermore, temperate zone perennials tend to respond well to predictable seasonal changes – fluctuations in daylight hours and temperatures can regulate hormones that direct critical cycles such as flowering or root development – so division won’t disrupt such hormone cycles, giving their root system more strength to cope with any trauma from digging, transporting and replanting a plant.
For this propagation method to work effectively, the plant in question must be mature enough to tolerate disturbance. Each section must possess enough viable shoots or roots so as to form fully grown plants, for instance if you’re dividing coral bells (Coralbells aquifolium), every section produced from division must possess all its leaves and roots intact in order to thrive and make full use of this propagation method.
For perennials, the easiest and most efficient method for division is digging up and gently shaking off excess soil from their entire clump. After this step, look for natural separations or points where stems meet within the root clump; use sharp knives or shears to cut the clump into sections containing both roots and shoots before replanting with fresh soil that has been prepared properly and water thoroughly to assist transplant success.
Digging
Dividing plants is an integral component of gardening, especially for perennials that form dense clumps or for some bulbs and tubers that need division regularly to thrive and give more flexibility within your garden space. Most perennials should be divided every two to three years while certain hosta varieties such as Hosta may need it more frequently for optimal growth.
Perennial plants often form complex webs of roots and stems that make digging them up difficult without damaging them. To facilitate the process, water the root mass extensively two to three days prior to your plan for division; this helps loosen soil particles while decreasing moisture loss from its surface.
Use a shovel or spading fork to dig around all sides of the clump you wish to divide and then pry underneath using the tool and lift gently. If necessary, cut into smaller pieces before lifting.
Size depends on both your needs and garden size, but each piece should be large enough to reestablish itself quickly. A general guideline suggests one-quarter the original root ball’s area – this gives each section enough time to grow into mature plants before needing further divisions.
When cutting fibrous and clumping root balls like those found in hosta, make sure each piece contains at least one eye, or small node, and some main taproot. Any division with at least several such characteristics is considered viable – this also holds true for perennial taprooted species such as balloon flowers (Platycodon grandiflorus; Zones 4-9) butterfly weed (Asclepias tuberosa; Zones 3-9) cushion spurges (Euphorbia polychroma; Zones 5-9).
As perennial gardens begin to come alive again in fall, now is often an optimal time for dividing many perennials. Soil is cool and moist while there’s still enough time before frost sets in for new roots to establish themselves in time. To get a better sense of when to divide which perennial, our handy spreadsheet lists popular perennials along with their optimal season for division.
Transplanting
As with any garden activity, plant division can take many forms. Rough division is a quick way of cutting across larger clusters of plants like phlox, rhubarb or shrubs with larger tools like digging forks or an axe and quickly dividing them into clumps ready to be planted immediately; fine division requires more selective splitting which might involve teasing apart sections or using sharp knives; plants with woody crowns or fibrous roots are typically split into rhizome-sized pieces to increase chances of survival once transplanted elsewhere.
Back Garden notes that perennials that thrive through propagation by division include those growing from rhizomes such as irises, asparagus and snake plants as well as ornamental gingers and heliconias. The optimal time to divide these plants is in spring or fall when they are dormant and less susceptible to shock from transplanting.
Beginning this method requires only a few straightforward steps, and the exact tools and supplies necessary will depend on your plantings and technique of choice. As a general guideline, gloves; sharp, sterilized knives/pruning shears/pruners; spade/shovel; and small containers to hold rhizomes until they grow into mature plants will all be essential. You may also wish to invest in sterile spray to clean all your tools both prior to and after separating plants.
For a simpler process, consider purchasing pre-grown rhizomes from either a nursery near you or online. This will make the task far more straightforward by cutting down on preparation work and waiting time associated with this task.
As with any form of propagation, divided perennials don’t always do well in their new environments, which makes it essential that proper conditions be provided during their transition into plant independence. Offering them proper watering and slow-release granular fertilizer will help ensure rapid root development while protecting newly divided perennials from harsh weather conditions is wise if experiencing transplant shock.