Some herbs send roots out on top of the plants stems. Others spread under the ground from crowns, roots, off-sets and specialized stems such as stolens and rhizomes.
What are stolens?
You’ll find stolens on mint plants. The stolens branch out and claim territory for the mint plants to grow. If you dig the stolens out and look at them, you will find that they will resemble roots. But look at them closer and you will see hairy roots growing from them.
Rhizomes are found on tarragon plants. They are fleshy looking and when spring comes, buds will swell on these rhizomes. From these buds, stems will form from these buds. It is from the rhizomes that children will form from the parent plant and you can take them and replant them into another area.
Mark the Herb Plants in the Fall
Dividing your herb plants will not only give you more plants, it will help prevent disease. In the fall, mark the plants that were vigorous growers, so you will know next spring the ones you wanted to divide. It is also a good idea to prepare the garden bed where you want to plant your herb plants. If you do that, you will be ahead of the game and not have a lot to do when spring comes. Of course, you can wait until the spring and do this when they are just beginning to burst up from the ground.
Divide in the Spring
In the spring, you will need a spade and a sharp knife to divide your herb plants. Before you dig the herb plant out of the ground, have the site where you want to plant your herb already prepared. Dig completely around the plant, and then pry the clump out of the ground. Leave the herb clump on your spade and gently remove the dirt form the roots. You can do this with your hands or use a water hose and wash the dirt away. Look at the top of the herb clump and find the buds. Use these buds as a guide on where to make each cut. When you cut the root section make sure that each section has several new buds each. Resist the urge to divide a clump into many sections. Sometimes just dividing your herb plant in half or into thirds is enough. Don’t forget, this is a shock to the plant and each cut sets the plant back a little.
Plant the Herbs
Plant the newly divided plant into the ground as soon as possible or the roots will dry out on you, killing the plant.
If you don’t feel like dividing your herbs in the spring, you can do it later in the season. When you do, resist the urge to plant it into the ground right away if the ground is in the sun. Your plants will stand a better chance if you transplant them into a pot first. Put the pot in a shady place or a protected place. Keep them there until the root systems have become established. Then move the pots into the sun starting at an hour a day and gradually increase the exposure time over the course of a week. This will help to harden them so they will have less stress when planted in the ground.