Expand your garden while improving the health of your plants.
Fire-red echinacea, sunny rudbeckia, daylilies with blossoms like stars fallen to Earth: perennial plants are a dazzling part of any garden, offering years of beauty and color without the need for replanting each season. But as these enduring favorites mature, they often become overcrowded. This is where the art of dividing and moving perennials comes in.
Why is dividing your perennials important?
As perennials age, they can become densely packed, leading to competition for nutrients, space and sunlight. Dividing your plants not only prevents overcrowding but also revitalizes perennials by encouraging new growth. It’s a rejuvenating process that can breathe new life into your garden, year after year, particularly if grown in raised beds or planter boxes.
Other benefits of dividing perennial plants include:
- Fewer pests and diseases: By dividing, you eliminate overcrowding, reducing the risk of diseases and pest infestations. Each division is more likely to thrive in its new location.
- Enhanced aesthetics: Well-spaced perennials display their beauty more effectively, creating a harmonious and visually appealing garden.
- Increased flowering: Dividing stimulates the production of new shoots, resulting in more flowers and a longer blooming season.
- Cost savings: Rather than buying new plants, you can multiply your existing perennials for free, saving both money and resources.
- Garden expansion: If you wish to expand your garden, division allows you to achieve this effortlessly.
- Great for gift giving: Divisions make great gifts at any time of year. You can share plants with fellow gardeners in season or bundle up freshly divided bulbs for holiday giving.
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How can I identify a perennial?
Perennials are plants that have a lifespan of more than two years, often living for many years, even decades. Unlike annuals that need to be replanted every year, perennials have the remarkable ability to come back each season. This makes them a popular choice for gardeners who want a lasting presence in their landscapes.
The most defining feature of perennial plants is their ability to survive underground during cold temperatures, often in the form of roots, bulbs or rhizomes. These underground storage organs allow the plant to emerge and grow again when the conditions are right. If you’ve ever admired a shrub rose or a dense thicket of black-eyed susans that have flourished and expanded over many years, you’ll have seen the benefits of perennial plants in action.
Which plants should you divide?
Not all perennials are candidates for division. When considering which plants to divide, look for the following characteristics:
- Overcrowded growth: Plants have become densely packed, with a noticeable decline in vigor and flowering.
- Large root systems: Perennials with extensive root systems have outgrown their allotted space.
- Offset or ‘daughter’ plants: Plants have produced offsets or baby plants near their base.
- Larger specimens: Larger, mature perennials need division to rejuvenate their growth and extend their lifespan.
Ensure each plant chosen for division is healthy and free from diseases or pests. Avoid dividing aggressive plants, such as those that reproduce rapidly through runners or rhizomes. If dividing, consider using barriers to contain their growth.
When is the best time to divide perennials?
The best time to divide and move perennials is in early spring or fall when the weather is milder and the plants are not actively flowering. Dividing at the right moment ensures that the transplanted perennials have ample time to establish themselves in their new location before facing the challenges of extreme weather conditions.
In general consider the following advice from the University of Minnesota Extension program:
- Divide fall-blooming perennials in the spring. This gives you more time to enjoy their blooms, among other considerations.
- Divide spring and summer-blooming perennials in fall. Ensure there are four to six weeks before the ground freezes so your plants can establish new roots before dormancy.
For more detailed information, read their comprehensive spreadsheet of perennials to find the best timing for your plants.
How to divide perennials: step by step
The heart of dividing and moving perennials lies in the division process, which can look different depending on your plants and location. Here’s what you need to know.
Prepare the new planting area
Remove weeds, rocks and debris from your perennials’ new location. Amend the soil with compost if it lacks organic matter.
Water and feed perennials
To prepare your plants, it’s a good practice to water them thoroughly in the days leading up to the division. Adequate soil moisture makes it easier to dig up the plant, reduces stress on the root system and increases the likelihood of a successful transition. Feed your perennials with a balanced, water-soluble fertilizer a few weeks before division. This will give them the necessary nutrients to recover and re-establish themselves.
Remove dead foliage
Before you divide perennials, assess the perennial’s above-ground growth. Trim or prune away any dead or diseased foliage. Be cautious not to remove too much healthy foliage, as it plays a vital role in the plant’s ability to recover.
Dig up the plant
Using a spade or fork, dig around the entire plant, keeping a good distance from the outermost roots. Lift from the ground, shaking off excess soil, and place it on a tarp or in a wheelbarrow for easier handling.
Separate the root ball
Examine the root ball for natural divisions, which may appear as individual shoots or clusters of roots. Gently separate these divisions by hand, ensuring each section has a good amount of roots and shoots attached. You can also use a sharp knife or pruning shears to make clean cuts if necessary. Trim back any long or damaged roots and remove dead or diseased foliage from the divisions. Prune top growth by about one-third to reduce stress during the transition.
Special considerations for different types of perennials
How you divide your perennials may vary depending on the type of perennials you’re working with. Consider the following:
Clump-forming perennials–such as daylilies, hostas, and some ornamental grasses–grow in tight, dense clusters. Divide them by separating these clumps into smaller sections, each containing roots and shoots. Replant these smaller clumps in their new location.
Rhizome-spreading perennials, like bearded irises, can be divided by cutting the rhizomes into sections, ensuring each section has healthy roots and leaves. Plant these rhizome sections in their new spots, with the rhizome just below the soil surface.
Tuberous and bulbous perennials
Tuberous and bulbous perennials, such as daffodils or some lilies, produce offshoots or bulbs that can be separated from the main plant. Carefully detach these bulbs and replant them at the appropriate depth for their species.
Caring for divided perennial plants
Once you’ve successfully divided and transplanted your perennials, ensure their health and vitality by tending to the following tasks.
Watering and mulching
Immediately after transplanting, give your perennials a good drink to settle the soil around their roots. This helps eliminate air pockets and provides moisture for the initial establishment. Apply a layer of mulch around the newly transplanted perennials to help retain soil moisture and regulate temperature. This also prevents weeds from competing with your plants for nutrients.
For the first few weeks after division, keep the soil consistently moist but not waterlogged. Take special care during dry spells.
Fertilizing and ongoing care
To avoid stress, wait until the following spring to fertilize your plant after transplanting. Use an organic, slow-release fertilizer, avoiding over-fertilization, which can harm the plants.
As your perennials establish themselves, prune regularly to encourage healthy growth. Remove spent flowers and trim back leggy growth to maintain the desired shape.
After division and moving, your perennials may take a full growing season or more to regain their full vigor and bloom. As the seasons change, your plants will settle in, and their resilience will reward you with renewed growth and beautiful blooms.
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