Hosta hakonecloaWhen to Divide?

by Terese at

  • Divide spring and summer bloomers in the fall.
  • Divide fall bloomers in the spring.
  • Divide on cloudy days with rain in the forecast.

Ideally, divide spring and summer blooming perennials in the early fall (at least six weeks before the ground freezes). Then divide fall blooming perennials in the spring when daffodils are peaking and the growing tips of your perennials are emerging. That’s about six weeks before hot summer heat. Whether you divide in the spring or fall, try to divide on cloudy days with light rain forecasted for several days.

Keep it simple.

Fortunately, if you forget which season your plants actually bloom in, you will usually be successful dividing any plant in either spring or fall due to cool air temperatures and warm soil temperatures. Northern gardeners tend to have better luck dividing in the spring and southern gardeners often have better success rates dividing in the fall.

What not to do.

If possible try not to divide plants when they are already stressed. This includes the time when they are in bloom, in the heat of the summer, on bright cloudless days and during drought conditions especially if there is a water ban in your town.

Emergency Division

Unfortunately, there are times when you have to roll the dice and take your chances moving or dividing a plant in full bloom on a blazing hot and sunny day in the middle of summer. Such as when a construction crew is ready to dig up your yard for emergency services or you are moving and suddenly feel the strong need to take some of your plants with you. Try to at least prepare a great amended hole for the plant to be planted in. Fill the hole with water and let it drain and fill again. If you have to hold the plant for several days before being planted, keep it moist and in the shade covered with soil, newspaper or burlap. Soak the roots in water for an hour before planting, cut the flower stems off and get it in the ground as soon as possible. You will have to baby the new division with consistent moisture and provide some afternoon shade (umbrellas work in this situation) until it is established. Think of it as a science experiment – just try not to do it with your prized plants or the expensive ones you would regret losing.

How often?

This is not rocket science. There is an old saying that generalizes a perennials growth rate and it is usually true. First year they sleep. Second year they creep. Third year they leap. Depending on the plants genus and species it may need division every few years to only a few times during your lifetime.


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