Many herbs have fibrous roots, so they can be lifted and divided quite easily.
When: I like to divide suitable herbs after the growing season – usually late summer through autumn. The best time to divide garden plants in general is when they are dormant. This gives them time over winter to establish themselves in their new position before the next growing season.
With bushier plants such as yarrow, oregano, sage trim any longer stems (usually where it has flowered) before dividing.
Lower growing herbs such as mints or thyme can easily be divided by gently scooping a wayward section of the plant onto your hand digger with about 5 to 10cm of soil, making sure you have plenty of roots, and snipping the section from the main plant.
Chives make a very attractive border. When your chive ‘clumps’ are big enough to divide you can create many new plants. I like to snip the tops of to about 10cm tall and pull any dried stems off when transplanting them.
Division Secrets: The best way to create healthy new plants is by choosing a vigorous parent plant.
Preparation is the other key. Water the parent plant thoroughly the day before dividing. Choose a day that is cool and cloudy or wait until evening. This helps reduce moisture loss.
Method: Lift the host plant from the soil with a fork or spade. Separate clumps by pulling off the vigorous young plantlets. If you have difficulty, try placing two garden forks or hand forks back to back and lever the handles together. This forces the plant to separate and helps untangles roots.
The centre of the clump is generally the older part which often becomes woody. Discard the woody section. Trim any damaged roots.
Make sure that each section (new plant) has it’s own healthy looking root system. Otherwise, your new divisions won’t grow.
Care: Replant the divisions as soon as possible, to the same soil depth as the parent plant. Cover new plants with shade cloth for the first week or so if it is sunny weather and keep them well watered. Mulch divisions taken in late autumn well, to protect the developing roots if you live in a frost prone area.