Pare perennials now for early spring blooms

Daily News correspondentSeptember 1, 2012 

September is probably the busiest month for weekend gardeners -- even busier than April-May, but without the fun of visiting greenhouses and buying plants.

Frost is just around the corner. We have to start preparing the garden for winter.

Those who grew vegetables need to harvest them and figure out how to preserve the extra cabbage, peas, berries, whatever. And, in addition to all this, we have to get ready for next year.

Getting ready for next year is the easiest: Plant bulbs and divide perennials that need it.

BULBS: Do yourself a favor and plant lots of them. Some prefer to scatter bulbs among perennials and later-flowering annuals.

This gets you that first touch of growth and color when you're most desperate for it -- sometimes pushing up through melting snow.

Others prefer the big bunch approach, for a graceful sweep of color, along a rise perhaps.

I say, why not both? But it's best to get advice from someone who knows what they're talking about.

See Jeff Lowenfels' Aug. 31, 2011 column, and sign up now for Master Gardener Robbie Frankevich's bulb class next Saturday, Sept. 8, at Alaska Mill & Feed.

The 10 a.m. session is probably full by now, but they've added a noon session. Seating is limited so call and register at 276-6016. It's free.

As for dividing perennials, it's mostly grunt labor, but well worth it. Dividing revitalizes plants you care about, improves bloomability, makes your garden look kempt and provides clones for planting elsewhere in your yard or for gifting to other gardeners. (Or you can just throw the excess away.)

A lot of new gardeners hesitate to divide perennials because they've never done it and fear damaging the plant. Don't worry about it. It's not brain surgery. Remember, you're dividing because you have too much of a plant. If you kill some, no biggie.

If you plan to replant what you cull, prepare the new planting site before you start.

The first question is always: Spring or fall?

There are some exceptions, but a rule of thumb, says Master Garden Jane Baldwin, is "divide spring bloomers in the fall; late bloomers in the spring."

Our season is so short that dividing in the spring often means no flowering that year, Baldwin wrote on the Master Gardener online exchange.

WHY DIVIDE? If you have a perennial that's been reproducing itself for years, it's likely the center of it is dead and doesn't bloom anymore, said Lacey Ott, horticulturist at the Alaska Botanical Garden. You want to fix this.

Also, many perennials are just rogues -- they spread way past the boundaries you think you established for them and suffocate their neighbors.

Others grow in on themselves and languish.

At a class on dividing perennials Wednesday evening, Ott let a group of wannabe dividers loose on a messy tangle of Aleutian speedwell that spent the summer laying tendrils over struggling nearby primula. This was a clearing-out operation -- the easy kind of thinning.

If you are actually dividing, not just discarding, water the mother plant the day before. You're going to stress anything you cut and water helps them recover.

It's also smart to pick a day after it's rained to divide because soft ground makes the whole thing easier. (Of course, our problem at the moment is finding a day "after" it rains.)

For fall dividing, begin by getting rid of the foliage, cutting it down two-thirds. You need to see what you're doing. Don't cut it entirely away.

Ott used a great little slicer to do this, called a sickle saw -- a short, very sharp curved knife with one serrated edge developed by the Japanese.

Dividing is about digging and cutting. Baldwin recommends a garden fork. Ott used a sharp-edged shovel.

TWO APPROACHES: They vary depending on how tough or impacted the root system is. One way is to dig the whole plant out of the ground and "go at it," Ott said. This is best with plants like iris and day lilies whose bulbs are so hard it's like trying to dig in cement.

Baldwin suggests putting the whole dug-up mound on a tarp and tackling it with a (Swedish) bow saw. When roots and bulbs are all grown together, you'll have to hack through some to save others. Just do it.

If there's a woody center that doesn't flower, cut it away, leaving an outer ring of good stuff. Cut that into smaller pieces. Each one is a new plant. If it has eyes, include two eyes in each cut in case one fails, Ott said.

For plants with less resistant or fibrous roots, you can remove discrete patches from the ground with a short spade or trowel. If it has hairy roots, cut a clump the size of a plant you'd buy.

Plant everything the same day you dig it up. Water it in. (That's why you prepared the new planting site before starting). Some plants will live through the winter in pots, but find out what you have to do to help them survive.

Advice for dividing perennials is like mac-and-cheese, everyone has a recipe and thinks theirs is best. Ott and Baldwin are very experienced and know what they're talking about.

You can find Ott at the Alaska Botanical Garden and Baldwin at the Master Gardeners website. I also use the Rodale "Illustrated Encyclopedia of Perennials."

This is my last column for the summer. I want to thank all the wonderful local gardeners who shared their wisdom with all of us, especially the Anchorage Master Gardeners Association and the Cooperative Extension Service.

For advice on putting gardens down for the winter, check Jeff Lowenfels' column next week, or log on to his website.

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