Spring finally decided to arrive and if you're like me, you're itching to get outside and enjoy the nicer weather. It's be a long cold winter that I am more than happy to finally say good bye to. Happiness is seeing perennials starting to raise their green heads or begin to flower (my Pulmonaria are having a party in the garden right now) and spring bulbs merrily blooming away.
One of my favorite thing about plants is the ability to propagate them and spread the joy in the garden or with others. Some sources say to dig and divide perennials while dormant others say when growth first emerges in spring – but I have been known to not follow either of those 2 pieces of advice. With a little extra care, I have had great success dividing at various times of the growing season. If you wait till fall to divide make sure to provide extra mulch for your newly divided plants to protect them from winter damage and then remove the mulch in the spring.
Note - Do not dig and divide perennials when they are in bloom. The reason is that they are using a lot of energy to produce those flower blooms and you want them to spend energy on root formation after dividing. Dig and divide either before or after they bloom. Wait to divide Pulmonaria (lungwort) and Phlox subulata (moss phlox) until after they have finished blooming in the spring
When digging up the plant – dig outside the root zone, not in it. The more roots you can keep intact the better. If the ground is dry, consider watering it a few days before you plant to transplant to make it easier on you and less stressful on the plant. Once you have the plant dug up – there are a few different methods for separating one plant in to many. You can gently pull the plant apart with your hands, use a sharp clean knife, or a double-fork method. The method you use will be related to what you are trying to divide. Perennials like daylilies can benefit from the double-fork method to make it easier to separate where as a clean sharp knife is best for dividing iris.
There are some perennials that should not be divided in until later summer and includes peonies, iris, and poppy. Some perennials are difficult to divide and transplant due to taproots regardless of what time of year it is. That list includes baby's breath, butterfly weed, balloon flower, blue false indigo and lupine.
You may be wondering if you can dig up and divide spring flowering bulbs and indeed you can! A good indicator that it may be time to dig and divide is if you are having fewer and fewer flower blooms each year. Tulips are more likely to exhibit that symptom more so than daffodils or smaller spring bulbs. Wait until the foliage dies back – usually 6-8 weeks after the plant has finished blooming to dig up and replant the bulbs. Carefully dig up the clump and separate the bulbs discarding any bulbs that are damaged or smaller then they should be for that species. It's best if the bulbs are replanted immediately, but if you have to wait until fall, store them in a cool, dry, and well ventilated location.
Hurray to finally having spring weather!