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"Division = Multiplication? Increasing Your Perennial Numbers"


Gardeners who may be new to the art, science, passion and plague of horticulture must find it overwhelming and laden with rules, do’s and don’ts and ton of folklore. Seasoned gardeners, those of us who spin the tales and folklore, often find tasks such as perennial plant division a bit confusing as well. Like most things in gardening there are of course some technical guidelines surrounding the when and if’s of plant division. Defining what a perennial is may be good as many of my readers are relatively new to gardening. A perennial is a plant that “is supposed to” come back year after year providing flowers and foliage in an improved state each season. I say, should come back because goodness knows, in Saskatchewan as an example, I have had sturdy, guaranteed tough, hardy perennials that last only two years then poof! To the considerable amusement of my family, the “great gardener” himself has lost some of the easiest plants to cultivate (always blame the weather FYI). So fear not newbie gardeners, there are no guarantees expressed or implied, you just take your chances like the rest of us.


The notion of division becoming multiplication intrigues my mathematically inclined friends, but it really is true. Perennial plants that are divided actually produce more plants or multiplying, increasing or adding to your collection. Of note, pieces of perennials make excellent currency for gardeners, so not only have you increased your collection but you may now trade for new plants to increase the scope of your assortment. Potential candidate that are high on the exchange currency scale are Hostas, Alchemilla or Lady’s Mantle, Heuchera or Arum Root and of course Rhubarb both decorative and edible forms. Rhubarb you say! One of the great unsung heroes of the Canadian garden is Rhubarb for certain. In many provinces gardeners have a very limited selection of coarse-leafed perennials if at all. Reliable Rhubarb fills that bill beautifully and also provides fresh spring stalks for a variety of recipes. There are many common perennials that make adequate currency for trade however some that should never be offered, at least to friends. Bishop’s Goutweed, Lamium(s) and Forget-me-nots rank very high in the “undesirable” category. Having received these and a few more species, I was cornered into an awkward situation. As gifts to my garden I of course was obligated to plant them; fearing a re-visit from the donor. Naturally I couldn’t make up the excuse that the plants died or didn’t winter well, how would that look? The moral is, be careful and be generous with the appropriate plant currency.

Division itself is very simple and best undertaken in the early morning or dusk, as harsh sun and heat are not favored by newly divided plants. Hosta are easily divided with a very sharp spade that you slide down accurately between obvious growth terminals. Not to worry if you miss and cut off a few leaves, this happens and the plant regains composure in no time.

The new home for the division should be prepared and waiting for the new transplant; I like to fill the hole with water. Re-plant the division at the same height as it was previously and water liberally again. There is no such thing as enough water at this point. Hosta are shade lovers so overexposure to sunlight is not an issue, but do water regularly for the first couple of days and do not feed them. Newly established roots are tender and the chance of burning them off with synthetic feeds is high. Compost and or good well-rotted manure mixed in with the original soil is always a good idea.

Lady’s Mantle (Alchemilla) and Arum Root (Heuchera) are somewhat more demanding than Hosta. Look at the base structure of these plants and you will see that they have an almost “rhizome-like” basal stem system. Often times, these runners will have already started to root on their own so only require a clipping and you have a new plant. These plants enjoy filtered to good light so are best moved in the evening, giving them all night and the next morning to settle into their new homes. Follow the same procedure in preparation and soil amendment, consider covering the plants with shade cloth or light fabric until they have perked up. In the event that there are no runners with roots, investigate closely and you will see natural formed crowns, or whorls of leaves, this is where you dig. Try to make your spade cut swift and deep removing as much soil as you can with the new crown.

Rhubarb doesn’t look at all good when it is divided, but it quickly gains strength and lives up to its robust reputation. These roots are very deep and quite large and carrot-like. It is likely that you will break the root(s) off when dividing so be prepared but not disappointed. Preparation and soil amendment is the same as above, with liberal amounts of manure and compost to hold extra moisture. Some gardeners cut the large leaves in half or more to reduce transpiration, adding to an even more unhappy looking division. Oodles of water daily will see your Rhubarb hale and hearty in less than a week.



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