Monday, September 17, 2012

Dividing Mediterranean Spearmint

by Renee Shepherd and Lindsay Del Carlo

Mediterranean Spearmint is a vigorous, hardy perennial that will grow happily in a container all year long. Mint plants spread by roots that will eventually fill the container.

In just one growing season, this vigorous grower can become root bound, with roots filling up the container and leaving little soil. The plant becomes stunted, doesn't thrive and produces only small leaves.

Mint will do best if the root ball is divided each year in early spring.

Step-by-step instructions for dividing  mint plants
First, lay down a tarp because this is a messy process! Remove the entire plant from the container. You will need a tool to help pry the plant out if the container does not have straight sides like this one. We use a Hori Hori (Japanese Digging Knife) but an old serrated kitchen knife will work as well. You will likely see that the thick roots have started to circle around the sides of the container and they may be quite bound together.

Remove mint from pot using a Hori Hori
Thick roots of mint bound in the pot
Next, with a Hori Hori or knife, cut the root ball first in half. Then cut one of the halves in half again so the you have 1/4 of the root ball to replant.

Cutting root ball in half with a Hori Hori
Piece of root ball to be replanted
Use new, good quality potting soil to replant the piece of root ball in the same pot.

New bag of potting soil to replant into same pot
First, put a layer of potting soil in the bottom of the container. Then set the root ball into the pot, then fill around the sides. You can shake the container back and forth to settle the soil down around the sides.

Fill the bottom layer first
Replace piece of root ball in center of pot
After the soil has been filled back in, trim the stems back by half so that it will grow back fresh new thick leaves.

Refill with new potting soil
Trim back old stems
Make sure to water it in thoroughly right away. This will help the roots recover quicker and will also help to settle the new soil in around the roots. This is an easy way to manage your Mediterranean Spearmint container. Dividing mint is a good way to control the container size that you need. It is not necessary to keep moving it up to a bigger and bigger container.

Watering in
Newly divided and replanted mint

6 weeks later, grown back after dividing
Mint will quickly begin to re-grow and produce large bright green leaves for you to enjoy all year. You can also replant extra pieces to have more containers around your garden, or cut them up and give them away to mint loving friends.

For pieces you are not keeping but want to compost, you should first shake out the potting soil from the roots and let the roots dry out in the sun for a few weeks so that they will not continue to grow. Mint roots are very resilient! Once they are completely dried out they can be thrown into the compost.


Sara D said...

This is great! Thank you :)

Donna Heber said...

Hi Renee,

What a lovely tutorial you have shared with wonderful photos. I hope you have enjoyed these first few days of autumn.

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