Divide and conquer! Actually, just have more plants

Division of a Shasta Daisy Clump
Division of a Shasta Daisy Clump

Divide and conquer! Actually, just have more plants

Fall is here, finally! And one of the most common questions I am asked is, “Is it too late to ___ “fill in the blank.

Is it too late to seed my lawn? Is it too late to kill weeds? The answer is no to both of these. You still have time. But the most popular question is related to dividing and transplanting plants: Is it too late to transplant? And if not, which plants can be divided in the fall?

Dividing plants technically can be done anytime, well, anytime during low environmental stress. I am sure no one was thinking of dividing plants during this summer’s searing temperatures and droughts. Spring and fall usually offer better conditions to divide plants.

Timing of division should usually be planned opposite the flowering period, because the division process can limit or eliminate the flowering for that year. But if you have plants that are desperate for division, and they have been flowering less or not at all, this is less important.

So, the early spring-flowering plants like peonies, bulbs and irises are best divided later in the year (now), and the late-flowering plants like mums and asters are best divided in the spring. There are many plants that can be divided early spring or after their bloom time: coneflower, Black-eyed Susans, bee balm or sedum.

The idea of plant division brings several more questions: What is the purpose of division? Do all plants need dividing? If a plant isn’t doing well, is it OK to divide? One of these questions really answers all of them — What is the purpose of division?

First, it is significant to note that plants are the only organisms that generate their own food. You may never have thought about that, but it is amazing. Plants, through the miracle science machine of photosynthesis, make their own food. You don’t see them at the drive-through picking up sugars and carbs. They make them from sunshine. Plants allow us to eat sunshine. … one of the coolest facts of all things nature.

So, plants, with little help from us, make more plants. In annuals, it is setting seed, and in perennials, it is setting seed and growing larger each year. By dividing, we get the biggest bang for the buck gardening –totally free extra plants.

Some plants need division to maintain a healthy habit and tidy look. For example, plants like lamb’s ears and ornamental grasses, after a few years start to exhibit “donating” (now I am hungry). But these donuts are not Boston cream or long johns; this phenomenon is when the center of the plant (sometimes called the “mother,” as it was the original plant you planted) dies out as newer shoots develop all around.

This can create a messy, half-dead look. It is nothing you as a gardener have done wrong; it is just the habit of growth of these plants. By dividing, you cut out the center and replant all of the many new plants around the original, now dead, center.

If you prefer plants that don’t need this type of necessary maintenance every few years, look to plants like the peony. Given the right conditions, which includes full sun, a peony doesn’t require division for 100 years. How is that for a Ron Popeil “set it and forget it” plant?

Another reason to divide is when plants start to look stressed and sickly. It is important to look for a disease or insect cause first. But if those don’t apply, a reason for decline can be that plants have expanded and used up the resources and start to fail.

Do you have perennials that just aren’t as robust blooming as they used to be? Do you have irises that are just all leaves and haven’t bloomed for a few years? Time to divide!

One other important iris issue is if your patch has started to fail and it looks like the iris plants are just melting away. You may have iris borer. You may also notice a slight rotting smell by your irises. Division here is the optimal way to rid yourself of iris borer and rejuvenate the patch.

There are four key factors to successfully dividing plants: plant dig up; sharp tools; a plan for the divisions; and the most important, aftercare.

Just like when you get a cut, a clean cut heals better and faster; so is the case for plants. I cringe when I see gardeners dividing their plants like there are in a tug-of-war game. Pulling at the leaves and trying to divide by brut strength while the plant is still in the ground is not the way.

Plan to dig up the entire plant by using my favorite tool, a trenching spade. This slender, deep shovel is the perfect tool to dig around the entire plant straight down; then using the spade as a lever to pop the plant out of the ground.

I like using an old but sharp butcher knife to cleanly cut the plant into as many pieces as I want (and also discard any damaged or diseased sections). This brings up another question: How many pieces should we divide plants in to?

It depends on whether you want new fairly mature, but fewer sections, of your plants, or do you want to spread the wealth around and create many new plants that will take some time to grow to maturity? The choice is yours.

After dividing the plants into sections, replant them and — this is key — only as deep as they were planted originally. Then be sure to water regularly. Not just on the day you divided and transplanted them, but regularly. Every plant, especially new transplants, need an inch of water between rain and water, each week.

Fall can be a dry season, so be sure to water your divisions regularly unless we are getting some good rain, sleet, or snow.

Remember even though the tops go dormant, the roots continue to grow until the ground freezes.



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