What plants should I divide in the spring?
One thing I love most about perennials in my garden is the fact they increase in size every year. Some of these plants will benefit from being divided and an added benefit is the satisfaction of adding more plants to my yard without spending any more money. Spring is the best time to divide plants that bloom after mid-June through the fall. Early spring bloomers should be divided in the fall.
Dividing perennials benefit your plants and garden in a variety of ways:
• Ever notice some of your larger perennial clumps looking donut like? Have your clumps started to die out in the middle and there is a dead or empty section in the center? These plants need some love. * If the clump has not been flowering as well as previous years the plant may have become overcrowded and the roots may be old and woody.
• Another problem causing insufficient blooms may be do to soil nutrient depletion. This may also cause stunted growth and yellowish leaves. You may be able to get away with adding fertilizer to give the plant a boost, but digging the plant up, dividing it and amending the soil with good compost before replanting and/or moving it will really help. * Sometimes persistent weeds will invade your clump. The best approach to tackle this is to dig up the entire clump and divide it, while removing all of the weed’s root you can find.
• As I stated one of my favorite reason is to be able to add more plants to my yard at little or no expense. By dividing out what I have I can spread them out or better yet start an entirely new bed. If I have more plants than I need I will offer the extras to neighbors. We have also done plant swaps, trading more of what each of us has for something new from someone else. If you have a neighbor who can’t get out in their garden or do as much of the heavy work, you can offer to help them out in exchange for some of the extras from their garden. It’s a win-win.
What to divide in spring?
As I said earlier the best plants to divide in the spring are summer and fall blooming plants. I have been known to break this rule on occasion and haven’t experienced many problems. I generally won’t divide spring-flowering perennials while they are blooming, but doing it immediately afterwards often works just fine. Primroses, for instance, can be dug up and divided into numerous pieces in late spring, giving them an entire season to recover before flowering again the following year. Same thing with many of the spring-flowering rock garden plants, such as Rock Cress (Aubrieta), Basket-of-Gold (Aurinia) and Moss Phlox (Phlox subulata).
Some exceptions to this are Peonies (fall only), Oriental Poppies (in July or August when they are dormant) and true Lilies (mid to late fall). Each of these plants can be temperamental and don’t do well with spring dividing.
Summer and fall-flowering perennials have the whole spring and early summer to recover from being divided, and most will give you an excellent flower display the same year. Spring is the very best time for dividing most ornamental grasses, and especially the fall-flowering types such as Maiden Grass (Miscanthus) and Fountain Grass (Pennisetum).
Traditionally, the time for dividing Bearded Iris is shortly after flowering, in July or early August. But if you have stubborn clumps that refuse to flower, then you might as well go ahead and divide them in the spring, since they likely won’t bloom this year anyhow.
How to Divide
If you are new to this you may be a little nervous and unsure of what you’re doing but don’t let that stop you, this is normal! Once you have some successes under your belt you will learn most plants are pretty forgiving, will recover quickly and be all the better for the experience. I have been known to get carried away at times by dividing plants into pieces that are too small and the results are sometimes mixed — some pieces grow well, some die but there is usually a net gain so I consider it a success.
The basic steps of dividing are simple. Once your plant shows signs of growth in the spring (an inch or two of new shoots is fine), dig up the entire clump. Try to be generous and get as many thick roots as possible. I like to dig about 4 inches or so beyond where the shoots arise.
A narrow and long spade (called a rabbiting spade)
is a handy tool for this, especially in a closely planted border.
Dig all the way around, then pry the clump out of the ground. Put down a tarp somewhere handy, and transport your clump there. Drop the clump a few times to knock off any loose soil or give it a blast of water. Then, go and find a knife… I’m using an old kitchen bread knife these days for larger clumps, but a paring knife, steak knife or special garden knife will do just fine. Look closely at your clump, sort of parting the shoots in an attempt to find a natural point where the clump can be easily separated. If there is no such point, then just be brave and cut directly down the center with your knife, from top to bottom. Once it’s split in two, then look at each half to see if there is a sensible spot to cut yet again, then split these each into two. Depending on how large the clump was, you can keep going if you like. Try and keep the sections generally of a good size, say the diameter of your fist or larger. Each piece should have both green above-ground shoots as well as roots below.
The best and most vigorous pieces are usually those found towards the outside of the original clump. The roots are less woody and can recover more quickly, giving you strong and healthy new plants. Discard old and woody roots from the middle (add them to the compost pile).
Certain perennials when dug from the ground will almost fall apart into pieces. Others will need a lot more effort to split. A few kinds (like Miscanthus) may actually require an axe or hatchet to get out of the ground and then chop into smaller sections. Don’t forget to remove all of the roots for any persistent weeds that have made a home in your plant.
Once your dividing task is complete it’s time to replant the pieces. Try to plant them at approximately the same depth they were growing and give them a good feeding with some compost. Water them in well at planting time, then maybe once a week for the first month unless spring rains are generous.