Thursday, April 1, 2010

Divide and Multiply

Would you like to have more plants for free? Now is a good time for dividing herbaceous perennials that do not bloom in the spring or early summer. Actually, it would not hurt spring and summer bloomers to divide them now, but you would probably sacrifice this year’s flowers. If you have plants with center die-out, plants that have outgrown their space or whose blooms are decreasing each year, it is time to dig them up.

Remember that disturbing the root system hinders the plant from taking up necessary nutrients and water. Soaking your plant well, preferably the day before you intend to divide, will reduce the trauma. If your plant has a lot of top growth, you can also reduce shock to the roots by cutting back the leaves by about 1/3. It is a good idea to have the holes prepared for your new plants before you dig up the original plant to limit the time the roots are exposed. 

That being said, I once left a huge hosta sitting on top of the ground all winter. Ooopsie. Unbelievably, when spring arrived, it put out luscious new growth and I split that puppy up and had a bunch more incredibly vigorous plants. That would not happen just anywhere; remember, I live in the moist and magical Pacific NW.

Dig up the plant you wish to divide and try to get a majority of the root ball. Divide the plant into new plants that are large enough and have enough roots that you don’t have to baby them but not so big that you will be back dividing the divisions next year. Some people use two pitchforks back to back; the idea is to insert them through the crown of the plant and then push the two handles away from each other. Sounds easy; I don’t have two pitchforks.

I divide most of my plants by digging them up and slicing through the crown and/or root ball with an old kitchen knife. You have to be very careful no matter what you use. If you go the pitchfork route, they can send you flying if you suddenly break through or if the tool itself breaks on a particularly difficult root mass. I once dropped my knife and it landed, point down, in the top of my foot. Went to the walk in clinic for a tetanus shot. Gardening can be dangerous if you are a klutz.

If the plant is too large, you can use a saw to divide the root ball. This doesn’t happen often in my garden because I’m constantly dividing plants. In fact it is a subject for amusement to my husband who cautions me to never buy a plant that doesn’t come with its own little suitcase, because it is bound to spend its life traveling.

Some plants may be divided in situ; once you are familiar with the Hakonechloa and Geranium underground structure of your plants, you will know which ones can be divided by merely choosing the right place and slicing straight down with your shovel and popping a division up onto the surface. Hardy geraniums (not pelargoniums), hostas, daylilies and some grasses, such as Hakonechloa, are examples of likely plants for shovel division.

As noted in my previous blog, plants are best divided when not in bloom so that all their energy can go to root and leaf growth. A moist, cloudy day, ideally followed by several days of gentle rain is preferable for all kinds of planting, including planting divisions. True confession: I have been known to dig up and move a rose in full bloom in the middle of our dry Mediterranean summer and have it live. It was a near thing, though.

If you have no other option but to plant on a hot, dry day, try “puddling in” as the Brits have it. Wait to expose your plant’s roots till the hole is ready. Dig the hole and fill it with water. Let it drain and fill it again. You want the surrounding soil to be saturated.  Dig your plant, replant and cover the root ball immediately. Form a soil dam or collar around the rim of the planting hole and water again. If necessary, and it probably is, rig some shade for the plant.

Speaking of water, remember that even drought tolerant plants require moisture until they are established. Now, get out there and make plants!

1 comment:

  1. Thanks for the advice. I'd never heard of "puddling in." What a great tip and a great expression.