How to Grow Bluets
Details on Growing a Shady Patch of this Native Woodland Plant
“Nothing is so beautiful as Spring –
When weeds, in wheels, shoot long and lovely and lush…
The glassy peartree leaves and blooms, they brush
The descending blue; that blue is all in a rush…”
🌿 Gerard Manley Hopkins, Spring
North America’s Blue Woodland Carpet
A month ago I was following the signs at Hole Park in the woodland to search out a pool of blue among the trees. In that location, the pool was created by the British bluebell, Hyacinthoides non-scripta. Now at home again, it struck me that we have our own blue flower that creates pools for the woodland in spring. Ours may be smaller, but it is no less delightful: the diminutive bluet.
I love that the Native Plant Trust describes Houstonia caerulea as “a tiny plant with an outsized personality.”1 It was named by Linnaeus in 1753, and it is just one out of twenty-four species in the genus Houstonia.
One of its common names, Quaking Ladies, comes from the wavering motion of its flowers when they are blown by the spring breeze. The Quakers were a religious group that settled heavily in the Pennsylvania area, and they were know for “quaking” while they prayed with great emotion. This native flower is also commonly known as the azure bluet, or simply, bluet.
Join me today for a closer look at three crucial factors for ideal growing conditions for bluets (which no one else seems to mention!), and detailed photos and descriptions on how to grow your own pool of bluets…
Native range
Houstonia caerulea is native to eastern United States and Canada, and can be found in “a variety of habitats such as cliffs, alpine zones, forests, meadows and shores of rivers or lakes.”2
The bluet has tiny leaves, like grains of rice that lie on the green moss in the Woodland Garden at Havenwood. Just near the marker #35 for the “Wood Chip Path” on our new map, there is a blue pool of flowers that keeps getting better and better this month as the warmer weather helps them to develop. As we get further into May, the blue pool will widen and then gradually begin to drain away as the flowers go to seed.
A description of the flowers:
“This small, delicate perennial is found growing in compact tufts, 8 in. high. The plants may cover broad expanses. Tiny flowers are pale blue with yellow centers, tubular, four-lobed, solitary, and terminal. Spatula-shaped leaves occur in basal rosettes. Stem leaves are small and the stems are unbranched. This lovely, delicate, flowering plant is often found in striking patches of light blue.”3
Three important conditions for success
It was surprising to me that none of the descriptions I found for Houstonia caerulea include the cultural markers I have observed over the past decade as I have worked to grow more bluets at Havenwood.
Here are three things that I tell all of my gardening friends to help them along to their own blue pools:
Moss: Bluets like to grow in moss! I do not seen that mention on any website description. Bluets seed into the acid moss, and their leaves are able to get to the light nicely on top of its short green tufts. To grow bluets, first grow a patch of moss. To grow moss you need two things, compacted soil and shade. More on that in the description below.
Less Grass: Every description says that bluets grow well with grass. Okay. But they grow even better without it! If I was reading only the descriptions then I would be tempted to put them into my Birch Walk, where I grow a perennial meadow right in my lawn. But it is obvious in the large patches that we have that the bluets grow better where there is less competition from the grass. In fact, I weed out the grass, and everything else, when I can.
No Leaf Cover: To make sure that your bluets survive over the winter, be sure to keep the leaves off of their moss in the autumn. One year I did not, and it significantly lessened the number of plants that I had. It took a couple of years to recover.
To summarize: Bluets seems to naturally thrive in sloped areas of compacted moss in shady woodlands that are kept clean of leaf litter by the wind (or your gentle rake).
Dividing bluets
So you, or your friend, have a patch of bluets and you want to spread them to a new area of moss. It is already mossy and shaded, and you are ready to dig some up and getting going.
First, I would take your division from the bottom of the slope. Seed drops down hill, so if you pull a patch from the bottom, you will be created a bare patch of soil that can easily be re-seeded by bluets in the coming year. Win, win.
Here is a photo of one section of my bluet slope down to the wood chip path…
I went down to the wood chips to kneel down, and began to look for a small clump of bluets to move. (top left below)
I found a small group near the path, and the next thing I do is weed it. I pull out from the clump the grass/dandelions/etc that are included so that I am not spreading it too when I dig it up. (top right)
I dig down with my soil knife about 3-4 inches to make sure that I am getting enough of the roots of the moss right along with the bluets. The bluets grow in moss, so it is coming along for the ride! I am moving both at the same time, since the moss is their growing medium. (bottom right)
Lastly, I take fresh soil and compress it into the hole made from removing the bluets. When I press it down, this will encourage compaction and for moss to regrow in this area, as well as the bluets.
Transplanting bluets
Transplanting bluets in the highest part of the woodland will ensure that their seed will fall down hill away from the original plant, and hopefully spread a bit easier into new areas.
Firstly, I like to find a spot in the moss where there are a few "weeds" (in this case, anything that is not moss). I found a spot that was at the highest level near the new stone area in the Moss Walk, and then I looked for a few grass weeds in the moss so that I could remove them while also planting a bluet plant.
Find the highest spot and some weeds to dig up. (Two birds with one stone, photo top left below)
Loosen the soil to create a hole that matches the small plant you have dug up. (top right)
Compress the plant plug into the hole and press the soil to compact it a bit. This will help the moss to regrow. (bottom left)
Group a few small new plants together in one area, in an irregular configuration, so that you can create a natural looking planting group. (bottom right)
Growing new patches of bluets
On top of the Moss Walk, I already have several spots that are filling themselves in from small patches that were moved in the past several years.
Thank you for this. When we moved here in 2011, there were bluets growing in the back lawn. We don't have them anymore but I would like to reintroduce them. They weren't growing in moss but in a damp area of the lawn that got part sun. Have you grown them from seed, or did you increase from plants already there? I don't think I've ever seen either plants or seeds for sale.