Cardoon (Cynara cardunculus) is a plant I wanted to try this season because it has foliage power. The leaves are long and deeply cut, the edges are sharp and pointy, and it has a soft silvery coloring. Almost a gray-green tone or like a silvery white, with more white tones under the leaves which are held on stalky stems with prickly edges. It is hardy in zones 7-11 and requires full sun. I used it as a tropical style looking plant for my container gardens and in the ground. And sold some at my Container Garden Party offerings in 2010.
This plant can grow to a very large size! Up to 6 feet tall. Mine did grow very quickly in my containers this past season, starting with a early June planting and continuing to do well all the way into fall. It didn’t stop performing. The texture and form works well in a container alone or planted with supporting candidates. I used it in 3 places: 1 in an urn, 1 in a huge pot, and 1 by my mailbox mixed with Sedum and Artemisia arborescens ‘Powis Castle’. I was testing out the scenarios and seeing how it did to determine if I would offer it again to my container gardening clients.
The urn was the perfect shape container for the Cardoon plant because the plant’s foliage rose above it and hung over by the tips, offering a dramatic effect. The downsize was the urn was not large enough to support the plant’s soil and watering needs, so it had to be watered too often. This became a nuisance because the soil in the urn dried out too quickly for the size of the root system. And then the plant began to suffer which made the insects nearby take notice. It got a bit attacked. I was disappointed. But the look of the plant fit the style of the urn perfectly. The plant is stately, grand, and commands attention. The urn is stately and stands tall as if commanding attention. It is hard to describe, but the feel of the container matched the feel of the plant. These are important aspects to selecting the right container for container plants. You may have a country look to a container and you need to pair it up with a country or cottage style plant, in my opinion. A formal container should have a more formal style plant. When you put a couple together that doesn’t match, it looks odd and takes away from each personality. But when you have the right pair, you can feel and see its beauty!
The mailbox planting of a Cardoon this same season surprised me as well. I absolutely loved how the silvery green of the foliage of this plant worked so well with the soft rosy pink blooms of the Sedum ‘Autumn Joy’ perennial planted with it. As the Sedum’s bloom color intensified to a darker red-plum during late summer to fall, the foliage of the Cardoon continued to support it. This analogous scheme used 2 of related colors (blue/silver foliage of Cardoon, the pink/burgundy bloom of Sedum). They lie next to each other on the color wheel leading to a harmonious blend.
The Artemisia arborescens ‘Powis Castle’ (Wormwood) perennial plant was also a great addition to the other two plants because it has silvery foliage like the Cardoon, BUT the foliage of Artemisia is soft and whimsical compared to the stark and stronge cutting edge look of the Cardoon. The Cardoon provided that stronger elemental form while the thinner foliage of the Artemisia softened its stature. Artemisia (Wormwood) is a fine textured plant that can also take full sun conditions, like Cardoon. It is hardy in Zones6-9, grows well in average to dry soils (lime-enriched (alkaline) soil, and bonus – is deer resistant! It is easy to grow and prospers in dry heat which we experienced during our dry 2010 season. Artemisias can be sheared back if they looks leggy later in the season. It is also feathery foliage favorite. (Reminder: Flowers? Not always needed for impact!)
Many know that Sedums can take the heat and drought too! Sedums have broccoli looking buds in spring, they turn pink and then darker pink into fall. By late Autumn, the rosy burgundy coloring still created a visual appeal with its the large Cardoon foliage. Sedums are known for their winter interest as well. The spent flower heads, turning brown and dry into winter, always look wonderful when ice or snow clings to it (although this big snow year for us in CT has hidden many at this time).
In summary, my experience is all three of these plants, Cardoon – Sedum – Artemisia – performed well from early summer to late fall. Each gave the other more impact in regards to coloring and texture. The Cardoon surprised me on how well it did by a harsh roadside environment too. It didn’t cry out for watering and it kept getting bigger. It was a showy curb side candidate in an unexpected place. I was thrilled Cardoon performed by the mailbox trio planting.
Yet for some reason the same Cardoon in my large pot of about 3 feet in diameter didn’t perform so well. It continued to get discolored leaves and did not thrive as well as the mailbox plant. I kept wondering what was causing this problem. The soilless medium used was of good balance, it was watered routinely, and had fertilizer appropriately applied. Sometimes plants just don’t want to cooperate. But by the end of the season, when I disassembled the large container garden, I took photos of the leaves. They were up to 2-3′ long!
I will still use this candidate Cardoon in the future and will look for plants of a similar texture. It provides great foliage texture and form. I know when people first saw it in a 5″ pot, they secretly thought, ugh. But Ugh no more. It provided a powerful statement in all three areas. It just needed more consideration for its ultimate size to assure an even more quality outcome. Cardoon does provide that Va-Voom!