My dwarf turned into a giant

My wife and I were outside, enjoying a very nice spring day, trying to complete some important garden chores the other day. We hoped the rain would hold off as long as possible – at least until we were finished with one major project. While we were working in the front garden, one of our neighbors dropped in and began to slowly walk around the path, carefully observing every conifer as he passed. He had a distinct expression on his face as he wandered around – something between a sneer and a look of suspicion. Finally he made his approach.

“Ed,” he said, “I thought you told me these trees of yours were dwarf.”

“Yes, many of them are dwarf cultivars, though, some are miniatures and others would probably be considered intermediate growers—” I said before he cut me off.

“Then explain to me again how it is that my dwarfs have turned into giants!”

Fortunately for me, going through this lesson is much easier with the visual aids readily available in the conifer garden than, say, in a coffee shop.

First, I pointed over to the group of our native Douglas fir (Pseudotsuga menziesii). I explained that these truly giant trees were very likely 80 to 100 years old. Then I walked him over to where I have allowed a few seedlings from these trees to grow for the past eight years. I showed him the length of last year’s growth. The central leaders of these young trees averaged 30 inches! Had I not been pruning these trees every year to encourage a nice Christmas tree shape, they would likely be 20 feet tall (remember that’s in just eight years). Then I walked him over to a nice old specimen of Picea abies ‘Sherwood Compact’. This tree is close to twenty years old and is just over ten feet tall.

Picea abies 'Sherwood Compact'
With annual growth of six to eight inches, 'Sherwood Compact' is classified in the Intermediate growth rate catagory.

“Ok, but how is that a dwarf then, it’s still too big.” He said, arms folded over his chest.

I took a deep breath and tried again.

I reminded him about the giant Douglas firs, their eight year old seedlings, and then I took him to a very special cultivar called Picea abies ‘Tompa’. This specimen is fairly young – about 15 years old – but it is less than three feet tall.

“See this one; it is just about the same height, after 15 years of growth, as just one year of growth of those young trees over there.” I said pointing back to the young Douglas fir seedlings. “The Douglas fir grows at an average of 30 inches per year. It continues to grow and grow over its lifetime into the giant forest trees you see at the corner of my property. This dwarf form will also continue to grow throughout its lifetime – just at a greatly reduced rate. Conifers don’t just grow to a certain size and then stop… if they do, they’re dead.”

Picea abies 'Tompa'
The dwarf cultivar, 'Tompa', may grow to be fifty feet tall... in 300 years!

“So, if this ‘Tompa’ grew for 300 years, it could be… 50 feet tall?” My friend’s eyes grew wide as everything began to make sense. “But Ed, when my wife brought home one of those conifers – at your suggestion – the tag said it would grow to 10 feet tall.”

“Well,” I answered, “depending on the grower, that listed size may have been for a 10 or 15 or even a 20 year plant. The better growers will give specific information. But remember, that’s not 10 years from when you buy the plant – you need to keep in mind that you may have just purchased a 5 year old tree.”

When considering a new conifer for your garden, remember that it will continue to grow throughout its lifetime. Upright growers continue to grow taller and taller, low spreading forms become wider and wider. Simple math skills are sufficient for anyone to gain a pretty good idea how large a particular conifer may grow. Determine the length of the growth of the central leader for the past year or two. Multiply a single year’s growth by as many years as you wish, and you will have a very good estimate at how large that conifer will grow in your garden.

A very large tree will grow at a rate of greater than 12” per year. Intermediate sized trees grow from 6” to 12” per year. Dwarf forms grow from 1” to 6” per year and finally, miniature conifers grow at less than one inch per year. If you purchase a true miniature conifer that is 15 inches in height or diameter, you have found a fairly old specimen and it will very likely cost you a good amount of money at the local garden center. On the other hand, an intermediate growing cultivar, that is 15 inches tall may only be three or four years old and to the uninformed, could seem like a real bargain in comparison.

Ed-
Conifer Lover

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13 thoughts on “My dwarf turned into a giant

  1. Perfect explanation of growth characteristics. Too bad we can’t have them grow to the size we want & then live happily ever after!

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    1. Yes, but if they only grew to the size we wanted, then stopped, we’d all get fed up with them.
      The art of pruning, the tasks of occasionally moving and thinning, and the acquisition of new plants are all about the life-long journey of conifer gardening (as is the case with any type of gardening).
      All gardens must change in order to develop and evolve, so on one hand it would probably make sense to let some dwarf or slow-growers such as Abies Lasiocarpa develop naturally, perhaps reaching 15 feet or so in 20 years (to some that would appear giant), whereas others such as Pinus sylvestris aurea could be annually sheared in late May / early June, and kept at less than 5 feet in 20 years. Left alone, the latter may attain even more than the Abies, and reach 20 to 25 feet (very giant to some!)
      Pruning, if necessary or desirable, must begin from the second year after planting on an annual basis, and must always be done with care, so as to preserve the natural characteristics of the species. This is an art, a learning curve, and an acquired skill.
      One only needs to explore a book on Japanese gardening to sense the painstaking work in developing and maintaining Niwaki and Bonsai conifers, such as Pinus parviflora.
      Most of us would not aspire to such judicious pruning techniques in our conifer gardens, but a little annual attention to the plant’s pruning needs and to the maths (regarding growth rates) can pay massive dividends in years to come.
      Whilst there may not be a more impressive sight than a well-maintained beautiful conifer garden, there may be nothing worse than being shaded in by a mini forest , never pruned nor allowed to develop with tough love.

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  2. Ed, Great post. This is exactly why I get so frustrated when the deer ‘nip’ at some of my conifers – they can eat off a year’s growth in one or two nibbles!

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  3. But they *do* slow down after enough time.

    We are blessed to have a 100 year+ scots pine on our property. Every year, it does put out new growth, but only about an inch worth – and it certainly isn’t a miniature!

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  4. Great information Ed. I think it’s a fairly common misconception about dwarf cultivars that they reach a determined height and stop. Most nurseries don’t bother to supply this information which doesn’t help the situation.

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  5. thanks for a really helpful post Ed, this has been something I’ve been trying to understand as sometimes I read a lable saying a tree is dwarf or slow growing then when I check the tree in a book or on the internet I find large specimens now I understand why, I wish the lable would say how old a tree is then it can be seen how fast or slow it is growing, as I have a large garden to fill I am looking for medium to fast growing trees, where I live the gales do a lot of pruning and shaping, thanks, Frances

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  6. Well said Ed. I would like to add that growth rates can accelerate over time, changing miniatures to dwarfs & dwarfs to intermediates.

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