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Geranium plant division 2
In this guide we look at how dividing your perennial plants can keep them healthier for longer.

Many perennial plants and bulbs spread and grow outwards from their original planting site, and these can then be divided up to thin out growth or provide new plant material. Perennial plants are those that live for numerous years and come to life in spring. Examples include sedums, geraniums, lavender and dianthus flowers.

When perennials are left undivided, they grow larger and eventually may start to die out or lose vigour in their centre, as well as becoming too large for their site. By dividing them in spring or autumn, their vigour is retained and new plant stock is created. Some spring flowering plants, like irises, are best left until after flowering in summer. Ideally perennials should be divided every three years.

Perennials have different growth forms, so a slightly different approach will be needed according to the type involved. Some retain a central ‘crown’, others produce ‘offsets’ (small plantlets), while others are tuberous in nature.

Bulbs also produce offsets, and groups of bulbs can be lifted and divided in a similar way. Again this is best done after flowering and when the foliage has died down for spring flowering bulbs.

  • Maintains vigour and health of original plant
  • Limits size of plant and stops it encroaching on other plants
  • Helps to control weeds that establish at base of plant
  • Increases plant stock for using elsewhere or as gifts for friends and family
  • Dividing a long established perennial can require strength and delicacy, so it maybe helpful to look at the section below on 'making the task easier' to include children
  • Children can get involved in potting up the divisions that you prepare, or digging holes for them to go into
  • Watering the divisions afterwards can be fun, especially on a warm spring day
  • Before starting, show them pictures of the plant flowering to encourage engagement
  • Lifting and dividing large perennial plants requires care (to prevent damaging the plant), and if you are using a pair of forks to divide plants, there is a lever action which involves strength and is tricky to work around. Make the soil easier to work by watering it well in the days prior to lifting your plants. The soil will be heavier but easier to move
  • If using two forks to divide is not possible, then a slower method can be used. Use a hand trowel to remove soil from roots a bit at a time. When the roots are exposed, use secateurs or loppers to cut the roots. Then use your trowel to clear the next lot of soil from the roots, and so on, until the plant is divided. This method may also be preferable for easily damaged plants
  • Know your limits. If a plant is just too big for you to manage alone, then ask for help
Dianthus plant division 3
  • Wheelbarrow or bucket for transporting
  • Garden fork, or two - to lever apart plant clumps
  • Hand fork
  • A cutting tool which will depend on the plant – secateurs, loppers, knife, garden spade, lawn edger
  • Pots and compost if potting on any roots
  • High phosphorous fertiliser to add to planting holes if desired
  • Watering can or hose
  1. Water the soil around the plant daily for several days beforehand if the soil is dry, to make the plant easier to lift out
  2. Use a garden fork to gently lift the plant, loosening the soil carefully first
  3. With large fibrous rooted perennials you can place two garden forks back to back in the centre of the plant and push the handles apart, levering the clump apart
  4. Smaller fibrous rooted plants like heuchera and hosta are generally too fragile for the ‘two forks’ treatment and can be teased apart using a fork or hand fork. This works well for plants that offset too
  5. Some woody or fleshy rooted perennials may need to be cut using a spade or knife, remembering that smaller divisions will generally take longer to recover and reach flowering size. Bulbs can be treated in a similar way, lifting carefully to prevent damage, and gently teasing the bulbs apart
  6. Whether you are potting up your divisions or replanting them directly into the garden, make sure they are well watered afterwards to get as much soil to root contact as possible

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