What’s Eating My Columbines?

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With such an array of beautiful colors, how can you resist columbines? Source: www.amazon.com

The columbine (Aquilegia spp.) is a highly attractive perennial and very popular as well. With its exotic-looking flowers, usually bicolored (the color range includes red, pink, yellow, white and violet) and often with long spurs that extend towards the sky, its beauty is hard to beat. In addition, the spurs are filled with nectar and attract hummingbirds and butterflies. Even its curiously lobed foliage, like the leaves of a ginkgo or a maidenhair fern, and carried on very thin petioles, is just charming. But columbines have discouraged many gardeners over the years.

Their flaw? Mangled foliage!

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Tunnels traced in columbine leaves show that leafminers are at work. Source: birdingnewbrunswick.ca

Columbines are subject to not one, but two leaf-eating insects … and they come back year after year. Thus, either its leaves become covered with white tunnels or blotches (work of the leafminers Phytomyza aquilegivora, P. aquilegiana or P. columbinae, depending on where you live) or they disappear entirely, leaving a small forest of bare petioles, the leaf blade having been entirely devoured by the small caterpillar-like larva of the columbine sawfly (Pristiphora rufipes, formerlyPristiphora aquilegiae), the adult fly of which is rarely seen.

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Leaves chewed right down to a stub are a sign sawflies have been active. Source: sproutsandstuff.blogspot.com

One or the other shows up every year, sort of dividing up the task. It’s as if the insects were saying, “It’s your turn this time. I’ll do the job next year.”

Learn to Ignore What You Can’t Change

The secret to growing columbines without becoming totally stressed out, at least from the point of view of a laidback gardener, is to learn to just let things happen.

In nature, columbines grow perfectly well despite the annual attacks of these two predators. True enough, the leafminer may trace whitish tunnels inside the leaf, but that doesn’t prevent the leaf from photosynthesizing and therefore flourishing. In fact, some photographers even find serpentine tunnels very photogenic!

And when the sawfly devours all the foliage leaving only stubs, the plant quickly produces a new set of leaves. Since the sawfly produces only one generation per year in most areas, the new leaves remain untouched and thus the problem is solved.

Wow! That was easy!

If You Feel the Need to Treat

OK, so you’re one of those gardeners who just has to react. (I personally think you should just take a Xanax, but that’s me!) If so, you’ll probably be dismayed to learn that there really are no good insecticides you can use to control columbine leafminer. Indeed, the tiny larvae (so small, all you’ll ever see are the tunnels they trace) live inside the leaf: most widely available insecticides act by contact and so won’t reach them. Yes, there are systemic pesticides, ones that are absorbed by the leaves and therefore can reach insects others can’t, but most were banished ages ago because of their extreme toxicity. Certainly, they are no longer being sold over the counter in most countries.

What then are you supposed to do with an insect that lives inside the leaf and not outside? The only logical solution is to cut off and destroy the affected leaves. This involves not only a fair amount of precision pruning, but your plant ends up looking like sawflies hit it, so is this really better than doing nothing?

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Sawfly larva. Source: Line Sabroe, Wikimedia Commons

As for the sawfly, whose larvae (rather stupidly, don’t you think?) live on the outside of the leaf, where you can get at them, there are several biological insecticides*, including insecticidal soap and neem, you can spray on to control them, or you can hand pick them and toss them, wiggling and squirming, into a can of soapy water. (Revenge is sweet!) But for that to work, you have to see them in time. Unfortunately, sawfly larvae are usually both numerous and very hungry: they can completely defoliate the plant in as little as 48 hours. That doesn’t give you much time to react!

*Note that the popular biological insecticide BTK will not work on sawfly larvae. It’s specific to caterpillars (larvae of moths and butterflies). Although the sawfly larvae may look like caterpillars and in fact are often called false caterpillars, they aren’t caterpillars but instead fly larvae and BTK will have no effect on them.

You Decide, But…

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How can you resist such beautiful flowers? Source: www.plantgoodseed.com.

Despite foliage that comes and goes in the middle of the growing season, the columbine remains a very interesting perennial that easily adapts to most garden situations. It grows readily in both sun and partial shade and in most soils that aren’t overly dry. It’s also very hardy: most varieties will grow in zone 3 or even 2, depending on the parent species, and up to zone 8 in mild climates. Columbines also have quite a long flowering season, often over a month in late spring and early summer. True enough, individual columbine plants don’t live very long (three or four years is the norm), but they self-sow modestly but assuredly, and thus come back to beautify your flower beds for decades.

I say, “Hurray for columbines! Your zits don’t bother me at all!” Can you do the same?20180603A www.amazon.com_

Perennial Doesn’t Mean Eternal

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Gaillardia is beautiful, easy to grow… and very short-lived: 2 or 3 years.

If you’re tearing out your annuals because they bloom only once and replacing them with perennials “because they live forever”, you may be making a mistake. Perennials (planted in appropriate conditions, of course) do live longer than annuals (1 year) and biennials (2 years), but not always that much longer. Some perennials live only 2 or 3 years, others twice that, others a little more, but very few will still be around in 40 years! If I had to estimate the average lifespan of a perennial, I would say 7-8 years.

This is much better than an annual, but you must still be ready to replace perennials from time to time: for the most part, they are not as long-lived as woody plants (trees, shrubs and conifers) most of which will probably outlive the person who planted them.

Short-lived Perennials

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Columbine (Aquilegia) is a short-lived perennial.

There is a particular group of perennials gardeners call short-lived perennials. They’re not exactly biennial, as the latter only bloom once, the second year, then die. Short-lived perennials have the ability to bloom more than once, but often flower the first and second years before they croak. The third year remains a question mark and as for the fourth… forget it!

The problem for the novice gardener is perennials don’t come with a “I’m beautiful but short-lived” label. When a “perennial” disappears after only 2 or 3 years, the disappointed gardener feels guilty and wonders what he did wrong. Yet disappearing after 2 or 3 years is normal for these plants: it’s not your fault.

When you know in advance that a perennial is short-lived, you can take precautions to prolong its existence. For example, taking cuttings ou divisions or multiplying it by seed. If you do this every two years, your short-lived perennial can return year after year.

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Mauves (Malva spp.) are short-lived, but generally maintain themselves through self-sowing.

Many of these short-lived perennials redeem themselves, at least partly, by reseeding spontaneously. Okay, they don’t grow back exactly where you wanted them, but if you are open to the concept of an English-style mixed border, where plants mix freely, you may come to find these ephemeral beauties very interesting. And what a joy they can be for the laidback gardener: they require no care whatsoever, showing up here and there as if by magic!

Although they may not live forever, short-lived perennials still have an advantage over their long-lived cousins: they generally bloom profusely the first year you plant them (many indeed will even bloom the first year from seed if you sow them indoors in early spring), which is certainly not the case of most long-lived perennials, most of which take at least 3 years before giving their best show.

A Few Short-lived Perennials

Here is a list of perennials that are generally short-lived. Those marked with an asterisk (*) tend nevertheless to come back year after year by self-sowing.

  1. Agastache (Agastache spp.) (some species self-sow*)
  2. Baby’s Breath (Gypsophila paniculata)
  3. Blanket Flower (Gaillardia x grandiflora)*
  4. Blue vervaine (Verbena hastata)*
  5. Blue-eyed grass (Sisyrhynchium angustifolium)*
  6. Brown-eyed Susan (Rudbeckia trilobata)*
  7. Cardinal flower (Lobelia cardinalis)
  8. Columbine (Aquilegia spp.)*
  9. Coral Bells (Heuchera spp.) (some cultivars are short-lived)
  10. Dame’s rocket (Hesperis matronalis)*
  11. Delphinium (Delphinium spp.) (longer-lived in cool climates)
  12. Echinacea (Echinacea spp.) (some cultivars are short-lived)
  13. English daisy (Bellis perennis)
  14. Garden mum (Chrysanthemum x morifolium) (some newer cultivars are long-lived)
  15. Gloriosa daisy or black-eyed Susan (Rudbeckia hirta)*
  16. Hybrid Tulip (Tulipa spp.)
  17. Iceland Poppy (Papaver nudicaule)
  18. Knautia (Knautia spp.)*
  19. Lupine (Lupinus x russellii)
  20. Maltese Cross (Lychnis chalcedonica)*
  21. Mauve (Malva spp.)*
  22. Orange jewelweed (Impatiens capensis)*
  23. Painted Daisy (Tanacetum coccineum)
  24. Perennial Flax (Linum perenne)*
  25. Pincushion Flower (Scabiosa spp.)
  26. Pinks (Dianthus spp.) (some species self-sow)*
  27. Rose campion (Lychnis coronaria)*
  28. Shasta Daisy (Leucanthemum x superbum) (‘Becky’ is long-lived)
  29. Tickseed (Coreopsis grandiflora)
  30. White corydalis (Corydalis ochroleuca, now Pseudofumaria alba)*