‘Thistle’ is a common name or synonymous name for a group of flowering perennials. Generally this refers to the genus Cirsium but in many cases ‘thistle’ is used to refer to other genera that are not cirsium. Principally, Thistle flowers refers to the family Asteraceae of which cirsium is subsumed by.
They are mainly endemic to Eurasia, Africa as well as Northern America where there are around 60 species. Even so, many species have been naturalised outside their endemic regions.
Moreover, thistles are considered an invasive weed by many agriculturalists for their ability to spread quickly thanks to rhizomatous roots.
However, we think thistles are really cool and have so much more to offer than their invasive weed label suggests.
In any case, thistles, while having sharp and prickly leaves, bloom into a beautiful inflorescence that many gardeners enjoy.
Like a beautiful woman, there is always an allure towards an entity that could potentially prick us but is also spectacular and beautiful.
The combination of beauty and danger permeates almost all nature, and thus thistles are of particular curiosity to many. There are many cultivars of thistle that have some great flowers worth considering in your garden.
In addition, thistles are appreciated by the birds and beads who love to pollinate the plant as well as feeding on them.
1. Cirsium Rivulare ‘Atropurpureum’
For American gardeners, look no further than this cultivar. This Is an example of thistle that has been naturalised to the North American temperate climate.
It remains pretty hardy within this climate, and needs good sun exposure as well as moist soil. By June the flower should be fully matured and at around 4 inches.
The flower of this cultivar is the main attraction, blooming into a lovely purple, pink color that many would describe a ‘fushia’, the color not the plant.
This compliments the harsh but dark green foliage that brings the dangerous element to the beauty of the plant. This is cultivated by many gardeners in borders for a little pop of color among green foliage.
2. Cirsium Rivulare ‘Frosted Magic’
In stark contrast to the previously listed cultivar, this Cirsium lives up to its name with some bold white colors. The inflorescence of this thistle is a little different too, being a little smaller and having more flower heads in general, especially on one stalk.
This would look great among other tall flowers that are colorful, the white brings a cleanliness that cuts through other colors. This would be great among some Zinnias or Helianthus.
Like the previous cultivar, this cultivar prefers moist and rich soil.
Those who can read latin may already realise this as ‘rivulare’ translates to ‘growing by a river’ so you can guess from that they enjoy watering.
This can bloom through to august, just make sure to cut the plant back in fall or it will self-seed into your borders, which you probably don’t want.
3. Cirsium Japonicum ‘Early Rose Beauty’
This is a japanese cultivar of the common thistle but is naturalised to most of North America as well as Europe. Even though this isn’t a rivulare species it still appreciates some good watering attention.
Although thistles will grow in part shade too. In any case, this will remain fairly hardy like the other cultivars. It blooms into late summer but should be cut back before fall to avoid self-seeding.
The inflorescence of this plant is a bright pink color, lacking the purple influence of the ‘Atropurpureum’, this particular cultivar is a denser and bolder pink color that will stand out among other flowers within a bed or border.
The flower head is deeply lobed and pinnate that makes the color a lot deeper and denser.
4. Echinops Ritro ‘Veitch’s Blue’
As mentioned, not all plants referred to as ‘thistle’ are technically of the genus cirsium.
This cultivar is part of the Echinops genus but is still considered a ‘thistle’. Echinops are self-seeding like Cirsium so make sure to cut them down before fall.
Echinops also flower around the same time, in late summer around August. Generally, Echinops need slightly less watering and maintenance than the Cirsium thistle.
One feature worth considering with an Echinops in comparison to a Cirsium, is that Echinops are much more globular than Cirsium which ends at a sort of half globe. If you want a full globe thistle, then Echinops are a good choice.
Specifically, ‘Veitch’s Blue’ has a very pleasant color that is somewhere in between blue and a soft purple. This is a very dream-like color and is quite attractive, not only to humans but many insects too who will appreciate the pollen.
Grow a few plants within a clustered area and see multiple globular heads rise above the other plants and really stand out with their dreamy color.
5. Echinops Sphaerocephalus ‘Arctic Glow’
This is another cultivar of Echinops that has some attractive globular inflorescence. This cultivar is great for sunny and also partially shady beds or borders, with a summer flowering time.
They are particularly good for a bed display that’s near the end of the summer season, as these plants will bloom through to early fall and will stand proud while everything else has died back.
Pair with other flowers that have a similar flowering period for a display that will last through to September if well kept.. Like Crisum, these Echinops enjoy rich soil but prefer well drained soil, while Crisium enjoys moist soil.
This ‘Arctic Glow’ cultivar produces globular displays of white pinnate petals.
The perennial is a great choice for late summer or fall displays where you want something sharp and bold to cut through other showier colors and flowers.
These Echinops can reach a decent height so will bring height as well as a sharpness to your display. These bloom for longer than Cirsium, so are good choices later in the season.
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6. Carlina Acaualis Subsp. Caulescens ‘Bronze’
This is a little bit of a curveball, but the Carlina is commonly called the carlina thistle.
The genus is distributed across Southern parts of Europe as well as Northern Africa, and as far east as Siberia and Northern China. The name ‘Carlina’ honors the Holy Roman Emperor, Charles V.
They are very similar to Cirsium but are actually identified as biennial herbs, however some species within this genus are actually shrubs and even small trees.
But in this case, with this specific cultivar, they resemble thistles greatly, as they are part of the thistle tribe ‘Cynareae’.
The inflorescence of this Carlina is similar but slightly different to your common thistle. The main point of difference being the presence of a pistil around which the pinnate petals form.
This particular cultivar, ‘Bronze’, has some silvery petals that surround the bronze colored pistil. This would look great among sunflowers and other Asteraceae that grow high.
One cool thing about the plant’s inflorescence that adds to their curiosity is that the inflorescence closes at night and also on rainy days, which earned the genus a common name ‘weather thistle’.
Another thing about the Carlina that could attract you away from the common Cirsium is the fact that they don’t self seed, rather, the genus will actually flower even better within a second year.
So some gardeners may enjoy this reduction of maintenance. Although some gardeners still chose to deadhead them along with other thistles just to be safe.
The Final Say
As you can see, ‘thistle’ is a term that ranges across quite a few different genera, however they all have similar qualities but different inflorescence. Some chose thistle varieties that don’t self seed as this can be a nuisance to remember to do and is an added layer on maintenance.
Other genera prefer drier soil, while others enjoy moist habitats, so choose accordingly based on your climate. What’s more is that some genera enjoy more sun, while others are pretty happy in the shade.
It’s worth growing thistles purely to keep the wildlife in your garden happy. If you keep the bees happy they will gladly pollinate all your plants for you.
As these cultivars demonstrate, the contrast between the prickly and hairy foliage and the beautiful spectral of each genera’s inflorescence combines to make some really interesting and curious plants.
One bed that gardeners love to create is a thistle bed, you could get all of your favorite thistle flowers of each genera and put them all in one bed.
Not only does this make horticultural sense as they all have similar watering and sun requirements, but can look stunning as the long and tall stems blow in the wind and you can teach people about the wide range of plants that the term ‘thistle’ can apply to.
Moreover, thistles are just great to keep the summer sights going all the way through to September, as thistles love to grow near the end of the season.
This is a great way to learn more about the seasons and also means your garden will stay pretty and well kept for longer than just the summer months.
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