Plant Now for a Carpet of Blue in the Spring

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20171003A Roger Bruce, Flickr

A spring carpet of Siberian squill in a lawn. The lawn will then go back to green all summer. Roger Bruce, Flickr

Sometimes it’s perfectly appropriate to want to impress visitors with beds of large, showy bulb flowers such as tulips, narcissus and hyacinths, but still, that’s not a reason to ignore the so-called “small bulbs,” those shorter, smaller hardy bulbs that rarely attain more than 4 to 8 inches (10 to 20 cm) in height, bulbs such as crocuses, chionodoxas and grape hyacinths. They can be just as impressive as the “big guys” if you know how to use them.

That’s certainly the case with Siberian squill (Scilla siberica), a very small plant with little drooping flowers. The advantage of this plant compared to other small bulbs is that it naturalizes so well, especially in lawns. A plantation of 10 small bulbs will only take a few years to become a carpet 10 ft2 (1 m2) in diameter. Eventually the carpet can extend to cover the entire lawn with pretty but tiny violet-blue flowers.

Siberian squill multiplies readily by seed. After flowering, the seed capsules that form on the flower stem ripen quickly and soon drop their seeds to the ground. Seedlings reach blooming size by the third year, which is very fast for a bulb. You can also harvest the capsules and distribute seeds to new parts of the lawn or to fill in areas where blooming is thinner.

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The nodding flowers of Siberian squill seen close up. Photo: ListItSweden, Wikimedia Commons

Siberian squill, in spite of its name, does not come from Siberia, but rather from south-west Russia, the Caucasus and Turkey. I assume that it got its geographically inappropriate name because of a mistake in identification (so often the case in the field of botany), but I like to believe that it comes from the great resistance of this plant to “Siberian cold.” Indeed, it is firmly hardy to zone 3 and well worth trying in zone 2.

The other advantage of the Siberian squill is that it will grow almost anywhere, from full sun to fairly dense shade, in soil that is either rich or poor and acid or alkaline and in zones that are both dry and moderately moist. It will even do well in clay, something not all bulbs can stand. In fact, about the only spot where it won’t succeed is in really soggy soil, because, like almost all bulbs, Siberian squill does need to dry a at least a bit during the summer. It won’t be happy, for example, in irrigated lawns and flower beds, as they are generally overwatered.

Good Things in Small Packages

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Scilla sibirica alba has white flowers. Photo: Aha, Wikimedia Commons

Each Siberian squill bulb bears only two to four narrow leaves and one or two arched flower stems about 6 inches (15 cm) tall, each with two to five downward-facing, star-shaped violet-blue flowers. The cultivar ‘Spring Beauty’ (the most commonly available variety) differs only slightly from the species, with flowers of a more intense blue. Plus it can be slighter taller. The only other commonly available variety is S. siberica alba which has pure white flowers.

Since Siberian squill is so tiny, you really have to plant the bulbs in groups of at least 10 to obtain a noticeable effect … and 25 bulbs is even better!

Easy Care

In any well-drained soil, dig a hole about 4 to 6 inches (10 to 15 cm) deep, incorporating mycorrhizal fungi and/or bulb fertilizer if you feel the soil is especially poor. Set the bulbs about 4 inches (10 cm) apart, then cover with soil and water well.

You can also plant the bulbs directly in a lawn where the plant will be pretty much unnoticeable except for the flowers, as the narrow strap-shaped green leaves masquerade as grass … and disappear anyway very soon after the plant blooms.

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To plant in a lawn, flip back a section of turf, dropping the bulbs (the photo above actually shows crocus corms) evenly into the hole, then put the turf back in place. Simple!

To do so, simply cut a cut out a chunk of turf on three sides, then flip it over on the fourth side, as in the photo above. This will give you a planting hole of about the right depth for your bulbs. Space them more or less evenly, the push the turf back into place and press it down with your foot. Finally, water well. The following spring, squills will pop up through the lawn as if it wasn’t there.

For more information on naturalizing bulbs in turf, read How to Naturalize Bulbs in a Lawn.

Siberian squill also naturalizes well in wooded areas because its flower stems just push right up through the thick carpet of leaf mold found there. And, of course, you can also grow it in a regular flower bed.

The Few Become Many

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Over time, a single bulb will form a cluster. Photo: Algirdas, Wikimedia Commons

Generally speaking, you won’t have to propagate Siberian squill: it will spread all on its own. However, if you want to see it multiply more quickly, after a few years of cultivation, you can dig up and replant the bulbs when they’re dormant (June to September). Just separate the bulbs (the original mother bulb will have produced hopdes of babies) and replant them in a suitable spot. And no, if you dig them up as soon as they go dormant (late spring/early summer), you don’t have to wait until fall until you do. Just plant them right away and get it over with!

Invasive?

Can Siberian squill be invasive? Of course! Naturalization means establishing a plant in a site in such a way that it seems to have grown there naturally and is typically done by allowing the plant to extend beyond its original planting spot.

Lovers of perfect lawns consider Siberian squill to be a weed. Not that its presence is harmful to the turf (it grows and flowers on a completely different cycle from lawn grasses, in the early spring rather than in summer and fall, so the two don’t compete), but lawn lovers prefer the appearance of a perfect green carpet over that a flowery meadow. If you’re a lawn maniac, just don’t plant squills!

Personally, I can’t get enough of flowers in my lawn and therefore greatly appreciate Siberian squill, certainly one of the very best flowers for turf.

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Totally green lawn = starving pollinators. Put flowers in your lawn, people! Photo: Photo: Clayton800, pixabay

Another advantage of flowering lawns is, of course, that they feed native pollinators, insects that are having a hard time these days due to the abundant use of pesticides and the dominance of asphalt, concrete and green lawns in our cities and suburbs. Plant squill and other small bulbs in your lawn and you’ll soon see the return of bees, hoverflies and other pollinators. They need early spring flowers to start their season and Siberian squill certainly seems to fill the bill!


Siberian squill: rarely does such a small plant create such an astounding effect. Get yours while you can: garden centers never seem to order enough to satisfy the demand for this tiny plant that is quickly becoming one of the biggest stars of the spring garden!20171003A Roger Bruce, Flickr

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Seeking the True Blue Flower

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Blue is one of the rarest of floral colors; only black is more elusive. And that’s probably because of the complex chemistry involved in producing a blue pigment, because bees, butterflies and other pollinators actually find blue quite attractive and easily visit blue flowers. That means that, evolutionarily speaking, blue flowers should be a good choice for blooms and flowers ought to have evolved as readily in that direction as they did towards the pink, white and yellow flowers that are so common.

But it turns out blue is hard to produce. The blue in flowers comes from a pigment that normally gives red or purple hues: anthocyanin (from Greek meaning dark blue). Various forms of it as well as related chemicals give flowers their blue coloration. But most plants with reasonable quantities of this compound produce purple to red flowers instead. Why?

Well, that’s complicated. Suffice it to say that various molecules and metal ions have to be present and also the environment near the pigment cells has to be alkaline. Many plants with true-blue flowers (notably in the families Boraginaceae and Convolvulaceae) have pink buds that turn blue as their environment becomes more alkaline, but most anthocyanin-rich flowers have acid sap and therefore their flowers turn out purple or red. In flowers, blue is a co-pigementation: it needs the right conditions to express itself.

Blue Flowers Are Highly Desirable

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These orchids have been dyed blue. Photo: Tangopaso, Wikimedia Commons

Blue flowers are much appreciated in the florist industry, so much so that dyeing or spraying white flowers blue to make them more saleable is a common practice. Dyes are even injected into living plants to give a blue tint to their flowers. That’s the case of the blue orchids that are so often seen on the market these days. They are actually blue-tinted Phalaenopsis and the next time they bloom, the flowers will be white.

There are scientists all over the world working to introduce genes for blue coloration into popular cut flowers—roses, carnations, chrysanthemums, etc.—with, so far, only mitigated success.

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The Applause rose has “blue genes”, but looks dark lavender to me! Photo: Blue Rose Man, Wikimedia Commons

The efforts to create a blue rose (Rosa) by transferring genes from blue-flowering plants into hybrid tea roses have resulted in a so-called blue rose, Applause, launched by Suntory in 2009 … but in my opinion, it’s not really blue. It’s closer to lavender. Of course, that is an exciting new color for roses, but the true blue rose has yet to be created.

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To me, these “blue carnations” from the Mooncarnation series are violet. Photo: Pagemoral, Wikimedia Commons

The same played out for carnations (Dianthus caryophyllus). Scientists transferred genetic material from blue-flowered plants, plus deleted carnation genes that were hindering the coloration. The resulting “blue” carnations (all those that I know of belong to the series Mooncarnation) are actually different shades of purple and violet. Now, these are new colors for carnations, of course, but they certainly aren’t blue.

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Newly introduced, this “blue chrysanthemum” is not yet commercially available. It’s closer to blue than blue roses and blue carnations, but still, it doesn’t look quite blue to me.  Photo: Naonobu Noda/NARO

Very recently (July 26, 2017), scientists announced the creation of the first blue chrysanthemum (Chrysanthemum x morifolium). It was obtained by inserting genes from a bellflower (Campanula medium) and a blue pea (Clitoria ternatea) into a chrysanthemum. Again, these new mums are being touted as true blue, but I still see a lot of lavender in the flowers and would definitely not call them blue.

Note that these manipulations are all examples of genetic engineering. In other words, these plants are GMOs, a term that scares the s___ out of many people. That said, blue roses and blue carnations have been on the cut flower market for a decade now and I have yet to hear any outcry.

True Blue Blossoms

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Ipomoea tricolor ‘Heavenly Blue’: now that’s a blue flower! Photo: Russel E, Wikimedia Commons

Obviously, there are true blue flowers, and in fact they evolved all on their own and have been around for millions of years. I don’t think anyone will deny that a ‘Heavenly Blue’ morning glory (Ipomoea tricolor ‘Heavenly Blue’) is blue. Moreover, this cultivar was not developed in a laboratory nor is it even a hybrid. Instead, it’s a selection of the wild I. tricolor, a species with naturally blue flowers.

And that’s just one example among many … well, among “quite a few.” There are probably no more than a few hundred true-blue flowers among the some 400,000 plants on this planet.

How to define “blue”?

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Bluebells (here, Campanula cochleariifolia), are not really blue, but violet. Photo: Jerzy Opiola, Wikimedia Commons

In horticulture, there is a long tradition of claiming any flower even the slightest bit close to blue as being a blue flower. Above all, violet-blue flowers—definitely more violet than blue!—are universally called “blue” and violet is an abundant color in the floral world. I’ve always felt this was a case of wishful thinking: we’d like to have blue blooms, so we accept anything close to blue as being true blue.

This seems to be a worldwide phenomenon, by the way: in all the languages I know (4), purple flowers are regularly called blue. Linnaeus himself, the father of botany, named many violet-colored flowers coerulea, which means blue.

Also, I suspect the definition of blue varies from one individual to another. As I researched this article, I realized that I take a rather narrow view to “true blue”. I tend to apply that term to lighter blues (cyan, azure, sky blue, etc.), while to my eye, shades that could be considered blue (indigo, cobalt, etc.) are violet. I’m not sure everyone would agree!

Obviously, we could take the scientific definition of blue as a benchmark. Blue is caused by light rays ranging from 450 to 500 nanometers … but who has a device capable of measuring that?

True Blue Flowers

Here are some flowers that, in my eyes, are true blue. I’ll admit it’s a subjective choice, but—hey! —I am the one writing this article!

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Allium caeruleum. Photo: col&tasha, Flickr

  1. Allium caeruleum (blue globe onion) – bulb, zone 3
  2. Amsonia spp. (bluestar) – perennial, zone 4 to 6, according to species
  3. Anagallis arvensis (poor man’s weather-glass) – annual

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    Borago officinalis. Photo: Sten Porse, Wikimedia Commons

  4. Borago officinalis (borage) – annual herb
  5. Brunnera macrophylla (Siberian bugloss) – perennial, zone 3
  6. Centaurea cyanea (cornflower, bachelor’s button) – annual
  7. Ceratostigma plumbaginoides (leadwort) – perennial, zone 6
  8. Clitoria ternatea (blue pea) – tropical climber, annual
  9. Commelina communis (dayflower) – annual weed

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    Corydalis flexuosa. Photo: jardinierparesseux.com

  10. Corydalis flexuosa (blue corydalis) – perennial, zone 6
  11. Cynoglossum amabile (Chinese forget-me-not) – annual
  12. Eryngium spp. (sea holly) – perennial, zone 4
  13. Evolvulus x ‘Blue Daze’ (compact morning glory) – annual
  14. Hydrangea macrocarpa (blue hydrangea), blue in acid soils – shrub, zone 6
  15. Ipomoea tricolor ‘Heavenly Blue’ (morning glory)—annual climber
  16. Linum perenne (perennial flax)—perennial, zone 3
  17. Linum usitatissimum (common flax) – annual

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    Meconopsis betonicifolia. Photo: Andrew Curtis, Wikimedia Commons

  18. Meconopsis betonicifolia (blue poppy) – biennial or short-lived perennial, zone 3
  19. Mertensia spp. (Virginia bluebells and others) – perennial, zone 4
  20. Myosotis spp. (forget-me-not) – biennial, zone 3
  21. Oxypetalum caeruleum (tweedia) – annual
  22. Plumbago auriculata (blue plumbago) – tropical climber or houseplant

Flowers That Are Often Blue

The following plants come in a wider range of colors, including many violets and purples, but also some true blues. With these variable plants, if you want blue flowers, make sure you pick the right cultivar.

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Delphinium ‘Blue Fountains’: this mix from seed contains blue flowers, but also purple and white blooms. Photo: J.W. Jung Seed Co.

  1. Delphinium spp. (delphinium, larkspur) – perennial or annual, zone 2
  2. Gentiana spp. (gentian) – perennial, zone 2 to 6, according to species
  3. Eustoma grandiflorum (lisianthus) – annual
  4. Hyacinthus orientalis (hyacinth) – bulb, zone 4
  5. Iris x germanica (bearded iris, garden iris) – perennial, zone 3
  6. Lobelia erinus (edging lobelia) – annual
  7. Lupinus spp. (lupine) – annual or perennial, zone 3
  8. Muscari spp. (grape hyacinth) – bulb, zone 3
  9. Salvia guaranitica (blue anise sage) – annual in cold climates
  10. Salvia patens (gentian sage) – annual in cold climates
  11. Viola x wittrockiana (pensée) – biennial or short-lived perennial, zone 4

So-Called Blue Flowers

What follows is just a short list of plants many gardeners consider to have blue flowers, but that, personally, I find too close to violet to belong in that group. So if you’re planning a blue border, you might want to skip these.

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Ageratum houstonianum ‘Blue Hawaii’: a pretty shade of violet, but not blue. Photo: Swallowtail Garden Seeds

  1. Aconitum spp. (aconite, monkshood) – perennial, zone 3
  2. Agapanthus spp. (lily of the Nile) – summer bulb or perennial, zone 7
  3. Ageratum houstonianum (flossflower) – annual
  4. Anchusa spp. (bugloss) – biennial or perennial, zone 3
  5. Aquilegia coerulea (blue columbine) – perennial, zone 3
  6. Browallia spp. (browallia, amethyst flower) – annual
  7. Campanula spp. (bellflower) – biennial or perennial, zone 3
  8. Echinops spp. (globe thistle) – perennial, zone 3
  9. Geranium spp. (hardy geranium) – perennial, zones 2 to 9, by species
  10. Hyacinthoides non-scripta (bluebells) – bulb, zone 4
  11. Iris sibirica (Siberian iris) – perennial, zone 3
  12. Iris versicolor (larger blue flag iris) – perennial, zone 3
  13. Lobelia siphilitica (great blue lobelia) – perennial, zone 3
  14. Scilla siberica (Siberian squill) – bulb, zone 320170829A

Laidback Gardener Tip of the Day

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Best Bulbs for Dry Shade

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Siberian squill naturalized in dry shade. Photo: Wikipedia

In general, spring-flowering bulbs naturalize better at the foot of trees with a taproot, like an oak, than trees with shallow, spreading roots, such as a poplar or maple. That’s because trees with shallow roots hinder the growth of bulbs, sucking all the moisture from the soil and emptying it of its nutrients, creating a dreaded condition know to gardeners as “dry shade”. Some bulbs, though, are exceptions to this rule and will tolerate root competition. This is particularly true of Siberian squill (Scilla sibirica), snowdrops (Galanthus nivalis), glory of the snow (Chionodoxa spp. ), trilliums (Trillium spp.), trout lilies (Erythronium spp.) and winter aconites (Eranthis app.). All will grow under deciduous trees, where sun is abundant in spring, but totally absent during the summer, and aren’t the least bit bothered by tree roots. In fact, they will usually spread on their own once they’ve settled in. Try them where your previous attempts to cultivate bulbs were unsuccessful.