Do plants heal?

I’ve been teaching plant physiology or related courses for a long, long time, and one of the tenets is that woody plants don’t heal.  In contrast to animal tissues, when trees and shrubs are wounded the damaged tissues are permanently destroyed.  Wounds are compartmentalized and covered with wound wood.  Arborists are fond of saying "plants seal, not heal."

That’s all fine and good for woody plant parts, but what about grafts?  Since grafting reconnects cambial and phloem tissues, is this "healing?" And what about nonwoody plants, like annual flowers and vegetables? 

Oddly, this type of information is sadly lacking in physiology textbooks, but it’s a question that I get routinely from gardeners.  And it’s not just an exercise in semantics.  People make some poor choices in treating tree wounds, for example, laboring under the false impression that such wounds should be treated with wound paint or bandages so they can "heal."

Yet another fine podcast

We’re popping out the podcasts like crazy!  This week the theme is “Gifts that keep on giving.” Along with the news tidbits and myth busting, I had a lot of fun interviewing shoppers at some Seattle nurseries.  I started out with two relatively simple questions about gardening gifts, and you’ll enjoy hearing the responses.  There are some great ideas out there! 

As always, feel free to let me know if you’ve got suggestions for future topics.  We’re halfway through Season 2, and I’m collecting spring ideas for Season 3.

I’m burnin’, I’m burnin’, I’m burnin’ for you

(with apologies to Blue Oyster Cult)

‘Tis the season for all things Christmas, including the annual hysterical reports of the dangers of real Christmas trees.  Along with heartwarming reports of Thanksgiving feasts at the local homeless shelter and live remotes of frenzied Black Friday shoppers, footage of Christmas trees going up in flames seems to be a staple of every network affiliate in the country.  In fact, in some cases the intrepid reporter will go to great lengths to insure that the Tannenbaum ignites the obligatory conflagration http://www.youtube.com/watch?v=P9dNS5WPncU

What the talking head doesn’t want to tell you is that a fresh, well-maintained Christmas tree is very difficult to ignite.  Numerous fire agencies and others have documented that a fresh tree that is kept watered will self-extinguish even if exposed to direct flame.  And faulty wiring is even less likely to ignite a fresh tree.  The story changes completely, however, if trees are allowed to dry.  http://www.youtube.com/watch?v=RNjO3wZDVlA

Of course, dry trees drop needles as well. So the key to keeping your Christmas safe (and tidy) is to get a fresh tree and keep it watered.  For many trees this means checking and re-filling the water daily, especially during the first week when the tree is brought in the home.  It’s not a real Christmas without a real tree – make sure it’s a safe one as well.  

Another podcast to chew on along with Thanksgiving leftovers

While our US readers enjoy the Thanksgiving holidays, you can all enjoy this week’s podcast, entitled “Leftovers.”  We discuss good leftovers (transforming orange peels into useful chemicals) and bad leftovers (fertilizer runoff), and then take a trip to an innovative company (Recovery 1) that recycles building demolition materials:


Huge piles of wood, wallboard, and other materials left over from demolition.

The initial sorting process – metals like nails are pulled out, wallboard is separated into components, and wood continues…

…to the end, where it’s chipped into different sizes to create a recycled mulch product.

Discarded carpet awaits separation into components that might eventually be used to help mop up marine oil spills.

All surface water from the site ends up in this detention pond, where it’s filtered and tested before it’s released to the environment.

Be sure to let me know if you have questions about the podcast, or even better if you have ideas for future topics and/or interviewees.

Just a nice photo…

…of late fall in our meadow at the Hahn Horticulture Garden, Virginia Tech.  

To our U.S. readers, happy Thanksgiving!  Pleasant weather here in Virginia means I’ll get to putter in the ol’ home garden (only to find some squishy brown things I probably should have dug up last month and now will need to replace. Oh well, that’s what great nurseries and garden centers are for). 

People let me tell you ’bout my best friend…

So far a mild fall has lingered here in mid-Michigan.  With temps in the mid-50’s I was able make much more headway on my fall clean-up than usual.  Typically we get enough early snows or cold-damp November gales that I don’t get to the last of the leaves and frosted hostas until spring.  Leaves are especially challenging here at Daisy Hill farm.  We have about dozen hardwood trees, mainly oaks and hickories, that drop a sizable load of leaves each fall.  For the leaves that fall in the lawn I follow Jeff’s practice and work them into the grass with the mower.  But that still leaves the leaves in the beds and every other nook and cranny they can find their way into.  Then it’s time to pull out the rake and my Craftsman 7.5 hp chipper/shredder; aka ‘My best friend’ (cue Harry Nilsson singing the ‘Courtship of Eddie’s Father’ theme).  I bought the shedder 8 year’s ago and it’s worked like a champ.  The manufacturer claims a 16:1 volume reduction and I’d say that’s a reasonable estimate.  My usual M.O. is to rake leaves, dead perennials, even small twigs into a series of piles and then work my way around the yard.  The main things to avoid are rocks (of course) and plants with long fibrous stems such as tomatoes, which can wrap around the impeller.  In a bit of serendipity, the original bag that came with unit finally wore to tatters so I ordered a new one from Sears on-line.  The new bag actually goes to a newer model and is almost three times the size of the original.  Having to continually empty the bag had been my biggest complaint about the system, so I’m in leaf shredding heaven now.  Since the oak leaves predominate I use the shredded leaves as mulch, putting down about a 1” layer each fall on tree and shrub beds.  It has a nice, natural appearance.  Plus it’s about 1% nitrogen.  Not a huge number, but a good way to recycle what nature have given us.  And certainly better than burning (or attempting to burn) leaves, which is still the most popular disposal method in rural Michigan.

You say horticulturalist, I say horticulturist

Keith Hansen, an Extension agent in Texas, has proposed a fun discussion topic:  horticulturist or horticulturalist?  We both prefer the former, though he points out that the introduction to my podcast uses the term "horticulturalist" instead.  Both terms recognized as real words and seem to be more or less interchangeable.

But I don’t really think they are interchangeable, and I don’t think Keith does, either.  Horticulture is a noun and horticultural is an adjective.  Specialty titles, like economist, botanist, or chemist, are based on nouns, not adjectives.  Otherwise we’d have economicalist, botanicalist, and chemicalist.

What do you think?  Is there a legitimate use for the word "horticulturalist?"