When and how to divide phlox

Last updated on May 10th, 2022

Phlox is a long-lasting plant that will flower every year, producing a variety of colourful flowers that attract lots of pollinating insects including bees and butterflies alike.

They grow very well in the right conditions but in some cases, they grow so well that you need to divide them. Every few years you will notice that your plant stops being as prolific at flowering and this is a good indication that it’s time to divide your plants if you haven’t done so already. You can get both perennial and lower-growing rockery plants.

Why do you need to divide Phlox?

Garden Phlox is best divided every few years to keep plants under control, help rejuvenate them, and in some cases, you might want to do it just to move them to a different spot in your garden.

---

When to divide Phlox

As a general rule, you should divide your Phlox every two to four years and you should only do so in the spring or autumn. The reason for this is you want to divide when your plants have no flowers or are producing very few flowers, and not when they are actively growing. Ideally, I would recommend dividing in spring if possible because they will take root quickly and really get going, rather than sitting around all winter.

Your plant will give you some indications of when it’s time to divide. The foliage will become sparse, they may start to grow in more of a doughnut shape with the centre of the plant dying off. If you notice the signs, it’s time to divide.

When dividing your Phlox in the spring, you want to do it right as the new shoots are appearing. If you divide them during the autumn, make sure that you do it at least five weeks before any expected frosts, the earlier the better so that they have more of a chance to put out new roots before winter.

---

How to divide Phlox

Water them thoroughly before making any divisions so that they are fully hydrated, ideally the day before so the plants are not soaking wet.

You can also prepare the area beforehand where you are going to plant your divisions by loosening the soil and adding any organic matter or feed such as bone meal to the soil and mixing it through.

Once you have lifted and divided your plant you will need to replant the divisions as soon as possible, ideally straight away. If you aren’t ready to put them in the ground yet you can always plant them in pots with potting mixture temporarily. If you do this in autumn we would recommend leaving them in these pots until the spring.

Using a spade, cut around the perimeter of the plant and lift it up, doing as little damage to the roots as possible.

Shake off the excess dirt from between the roots so you can clearly see what you are doing. Separate the Phlox into multiple sections that have an adequate number of roots to regrow on their own and then cut them with a clean, sharp knife.

Plant them immediately and water them thoroughly after planting and keep them well-watered until they have established themselves, being careful not to overwater.