The importance of knowing your plants

One of the first courses a horticulture student takes is plant materials, or, in the case of a forestry student, dendrology.  Why?  Pretty simple; it’s hard to select plants if you don’t know what they are and what they’ll do in the landscape. Of course, the classic example is a large tree or shrub planted in a tight spot that eventually devours an entire house.  But we usually don’t have to look too far to find situations where a homeowner or landscaper clearly had no idea what plant he or she was dealing with.  To wit, a couple of recent examples of poor plant choices (maybe this can be our next series after “Why do nurseries still grow THAT?”)

I spotted the first example wandering through downtown in my hometown of Olympia, WA.  At first glace it looks like an ordinary hedge; boxy to by sure, but nothing remarkable.

As I passed by though I noticed the hedge was actually a weeping Norway spruce (Picea abies ‘pendula’ – actually it could have been an ‘inversa’ – the repeated butchering made it hard to tell).  Either way, what could have otherwise been a fairly interesting plant had been reduced to a squared-off blob of blech.  The other side, of course, is that if a squared off blob of blech is truly desired there are cheaper and easier ways to achieve the effect.

The other example of the perils of not knowing your plant material comes from northern Michigan.   This case represents that other extreme of trees that grow too large for their space.  Here the homeowner wanted to screen his house (on the left but out of camera range to protect the guilty!) from the railroad track on the right of the photo.  Solution: Plant some conifers! Sounds like a good idea to me.

Only problem – the owner chose to plant the screen with dwarf Alberta spruces!  As with the blob of blech, the property owner could have achieved the desired screen in a couple of years and at a small fraction of the cost with seedlings from their local conservation district or seedling nursery.  In any event, we’ll check back in about 40 years and see how it’s working out for them…

 

Clematis calamity solved

Some good and creative guesses about why the Clematis leaves had interveinal necrosis.  While iron and manganese deficiencies both cause interveinal chlorosis (veins are green, areas between are yellow), the necrosis indicates tissue death between the still-living and green veins.  Very simply, this has been caused by water loss.

During transplanting of the vine, I had to remove them from the fence and lay them out on the ground.  They remained this way for a couple of days.  For much of the foliage, this meant that the lower leaf surfaces were now exposed to the sun.  As with many broadleaved plants, the upper and lower leaf surfaces are morphologically distinct:  the upper surfaces have a thicker waxy cuticle and epidermis, with few stomata, while the lower surface lacks much of the cuticle and is loaded with stomata.  When the leaves are turned upside down, the shade-adapted lower surfaces now receive intense sun exposure: water evaporates quickly from these unprotected leaves and the tissue dies.  The only parts of the leaf that don’t die are the veins, which remain full of water as long as the roots are functional.

So both LisaB and Benjamin identified sun exposure as the culprit behind the damage.  But as with many environmentally-induced plant problems, the ultimate cause is water stress.

Friday quiz – yet more clematis calamity!

If you’ve been following the saga of our clematis, you’ll know that first they suffered iron toxicity (from the waterlogged soil they were in) and then were dug up and replanted in containers.  Last week I showed you what happens when you vigorously work wet soil – yet more waterlogging!  During the transplanting process, I took more pictures:

This damage is NOT from the iron toxicity problem.  It appeared during the transplant process.  What caused it?

Answer on Monday!

Jicama (The Yam Bean)

Every once in awhile I get the urge to try and find something interesting in old literature, and today was one of those days.  So I went over to my pile of old “Journal of Economic Entomology” journals and snatched a 1943 issue from the top.  The pest issues that we had to deal with during the war years were interesting because resources were tight — we had DDT (and lead arsenate), but all of it was going to the front to protect our soldiers from lice.  So scientists back home were trying new things.  One which I had never heard of before today was getting a serious look: The yam bean.  The yam bean is a tropical legume which has a great deal of potential as a high nutrient food crop (the root of the bean is what is edible, not the seeds).  The food part is interesting to me, but more interesting is the fact that a dust could be made from grinding the beans into a powder which would kill insects.  After looking through some articles I discovered that the primary source of toxicity in the yam bean is rotenone and some similar chemicals.  I’m not a big fan of rotenone, still, this plant is fascinating.  An edible root and seeds which can be used very effectively as an insecticide.  Why wasn’t this plant more common 50 or 100 years ago?  What other plants are we missing out there which are useful?

Why do nurseries sell this plant?

I wish I were more like Holly…wandering around nurseries finding pretty and unusual annuals and perennials to get excited about.  Instead, I seem to gravitate to plants that annoy me.

Today while looking for some trellises (for those containerized Clematis vines that I’ve been torturing) I saw pots of the Equisetum hyemale (“a tall, evergreen, spreading, reed-like grass”) for sale:

 

As readers of this blog surely know, Equisetum spp. – or horsetails – are not grasses but primitive relatives of ferns.  That taxonomic blunder aside, the thought of deliberately planting any Equisetum species in a landscape sends shivers down my spine.

Now E. hyemale is not as weedy as E. arvense, but in nearly every seminar I give on controlling weeds with mulch someone asks about getting rid of horsetails.  Short answer – you pull.  And pull and pull.  There’s no good herbicide for them, nothing seems to eat them, and they spread aggressively.

And speaking of eating, did you know that horsetails are poisonous?  They contain an enzyme (thiaminase) that deactivates thiamin (vitamin B1) in the unfortunate consumer’s body.  The most common victims of horsetail poisoning, ironically, are horses.  Horsetails are considered noxious weeds in pastures used for grazing – and yes, they are native to the United States.

Sure, horsetails are interesting looking plants.  But do you really want something in your garden that the production nursery describes as having “indefinite spread?”  And how does keeping them in a pot, as one production nursery recommends, keep them from spreading spores?  Especially if you plant them “in or around ponds and streams?”

I just think this is such a bad idea for home landscapes.  Even if it is a native species.

Lamb’s Ears Revisited

A bit more on my recent travels to the big floriculture conference in Columbus, Ohio.  I always try to make it out to the Chadwick Arboretum & Learning Gardens, on the campus of THE Ohio State University. There are several components, including trials, a large arboretum, and several small gardens.  My favorite is the Steven Still Perennial Garden. It’s a lovely mixed garden, designed by Adrian Bloom (Blooms of Bressingham), and was installed in ONE DAY by their garden volunteers – 2005, I think.

Watching it grow has been fun. I noted [ with pleasure] that they’ve already had to start cutting back and removing some things. This makes me feel better because I am The Queen of Planting Too Close

A few highlights:

I thought of y’all when I saw
this…remember our conversation about Stachys the other day? Here’s a
new one on me: Stachys byzantina ‘Silky Fleece’.   What teeny, tiny
little leaves! And seemed to be limiting itself to a small area on the
edge of the border. Introduced in 2006 by German seedmeisters Jelitto
Perennial Seeds. They missed the boat on naming it…could have all kind
of fun with ‘Little Lamb’ or even ‘Mary’s Little Lamb’ as the director
for their North American office is Mary Vaananen. Heh.


My foot is just in there for scale – I’m really not that inept a
photographer.

 

A gorgeous flock of Rhus typhina ‘Tiger Eyes’.  Hardy to Zone 4, the foliage is golden in summer, blazing apricot in fall, a wonderful shrub accent in any garden… What? Hang on a sec.

Correction:
That’s Rhus typhina ‘Bailtiger’ PP16,185. Trade name is First Editions® Tiger Eyes® Cutleaf Staghorn Sumac. Well, that took all the fun out of it.

Moving on…



Belamcanda chinensis – Blackberry or Leopard
Lily.  A tough cookie, this midseason bloomer takes drought and even
reseeds a little bit in my home garden. The pods burst open to
reveal a cluster of seeds that look exactly like a blackberry. These
weren’t quite that far along, but in between flowering and seed setting, they
do something else interesting..


The petals twist up into these hilarious
little bundles. I have no idea why or what for. Just kind of neat.

All for now!

Clematis conundrum clarified

Friday’s puzzle was tricky!  I will preface the answer by saying I don’t do a lot of container plants except for annuals.  When I plant up annuals into soilless potting mix (which is dehydrated), I work in the water thoroughly into this fluffy medium.  Friday’s situation was a little different.  The Clematis are more or less permanent residents in these planters, so I use real soil rather than potting mix.  (This will reduce or eliminate the shrinkage you’ll get if you use soilless media, as these highly organic materials steadily decompose.)

But what I thoughtlessly did was to mix water into my nice screened clay loam like it was a potting mix.  The result of vigorous mixing is to break down the soil structure and drive water into all of the pore spaces, resulting in a totally waterlogged soil:

After my "D’oh" moment when I realized my error, I potted the second Clematis into loose soil and let gravity work the water into the larger pore spaces. This passive approach protected the soil structure and left some of the pore spaces filled with air rather than water, so that the water drained through rather than sitting on top of the compacted soil:

This demonstrates one of the rules of working with landscape soils:  you should avoid any potential compaction when the soil is wet.  (It’s the same reason you shouldn’t stomp on wet backfill as you’re transplanting trees and shrubs.)  As Ginny pointed out, you’ll create a cement-like structure – not conducive for water movement, oxygen availability, or root growth.

Friday quiz – the tale of two clematis continues

A few weeks ago I showed you photos of iron toxicity in a Clematis planted in a soggy soil (perched water table).  Because this area is just not conducive to plants, we’re putting in a small deck.  This necessitated the excavation of two Clematis, which were both suffering from wet feet.  (Needless to say the root mass was very small and shallow on both plants.)  We decided to put them into large planters with conical trellises and use them as deck plants.

During our pond excavation we retained the topsoil and sieved it for uses just like this (for woody planting, not annuals).  The soil is a clay loam and has been stored in a garbage can to keep it dry.  Anyway, the first pot I filled with this good soil, added water, and worked the soil with my hands to ensure it was thoroughly hydrated.  As holes developed, I added more soil and continued to work it in by hand.  I then installed the first plant and watered it thoroughly.

After observing what happened during the next several hours with this plant, I installed the second plant differently – I watered the soil but did not work it by hand to hydrate it.  I added the plant as before and then watered everything thoroughly; I added soil where holes developed.  I then redid the first container in the same manner as the first.

What happened to the first container that caused me to change my installation technique?  And why didn’t it happen with the second container?  Answers and photos Monday!

Want an organic source of nitrogen that isn’t shipped from halfway across the world? Urine luck

There are lots of organic fertilizers out there:  Fish emulsions, corn gluten meal, guano.  Many of these fertilizers (all that I listed above with the exception of the guano) are by-products of some other industry.  Still, they need to be shipped from somewhere to somewhere to get to our garden and so they cost energy — and of course they cost us money.  But there is a high nitrogen fertilizer that you can use which doesn’t come from a long way away, and that’s pee.  Holly  mentioned using pee to help compost piles of stray a few months ago (you can find the news story on the right side of this blog), and I, for one, think it’s a great idea.  But really, pee can be used as a fertilizer without the compost.

Yesterday I was working on a project and decided to goof off a little by figuring out how much nitrogen was actually in urine.  Here’s the conclusion — Urine contains about 4,000 pats per million nitrogen.  In terms of what plants can handle, that’s a lot (which is why dogs produce “dog spots” when they pee on a small area of ground — too much nitrogen in a small area).  400 parts per million nitrogen, applied once a week in irrigation water, is what you might apply to encourage the growth of greenhouse plants.  Urine, by the way, is also relatively sterile (unless you’re dealing with a bladder infection) and so using urine is relatively safe as long as it’s used quickly.  It also conserves water because you don’t need to flush.  So, the way I figure it, you could mix 1 part urine with 9 parts water and have a really good once a week (or two weeks) fertilizer application for your flowers (I don’t know if I could bring myself to fertilize cabbage, broccoli, or tomatoes with it…).  You’d be saving yourself the cost of fertilizer, saving the environmental cost of shipping the fertilizer you might otherwise purchase, saving water, and you’d have something unique to tell your gardening friends about.  Win – win situation as far as I’m concerned.

Restoration ecologists – you need us!

Restoration ecology – the science of restoring degraded ecosystems – is another branch of applied plant sciences.  Oddly enough, very little plant science makes it into the scientific literature of this field.  This has driven me nuts for a number of years after reading an endless stream of papers where no mention is made of how plants are selected, installed, and managed.  Or worse, some ancient horticultural practices are used – like amending the backfill with organic material rather than using just the native soil.  Here’s what that will lead to:


Native soil discarded in favor of “lite-n-fluffy” amendment

The whole story

Restoration failures like this are often attributed to more esoteric causes, like lack of local plant gene pools in the plants used.  Believe me, even local populations aren’t going to survive poor installation techniques.

Thus, one of my recent graduate students conducted a meta-analysis of the applied restoration ecology literature to analyze it for horticultural content.  The results were not encouraging.  In Kathleen’s thesis abstract, she states:  “…careful selection and handling of planting stock, site and soil preparation, and rootball preparation, essential to increase survivorship of planted seedlings, are infrequently discussed in peer-reviewed restoration publications…Findings from this review support that restorationists either do not understand or are not providing important information to their peers, stakeholders, or the public on significant horticultural aspects of the restoration process.”

Now I know most of you are not restoration ecologists…but I’ll bet many of you are interested or actively involved in planting or maintaining native plant habitats, public greenspaces, degraded urban lots, etc.  The science behind gardening is just as applicable to these “wilder” areas as it is to home landscapes and gardens.


Failure of entire installation.  Note suckering from the roots – an attempt by the tree to establish a shorter crown.  (It’s easier to transport water to a short crown than a tall one, and suckers are often a symptom of root failure)