Cynara cardunculus, or cardoon, is also known as an artichoke thistle. It is a member of the sunflower family, and is native to Mediterranean climes. The giant coarse toothed leaves are architectural in form, and incredibly dramatic. A lot of that drama comes from the fact that those leaves are a very bright silvery gray. These silver leaves, in the right light, have a decidedly metallic cast. This amazing photograph of a cardoon is from www.greatplantpicks.org. Great Plant Picks is an educational program of the Elisabeth C. Miller Botanical Garden which debuted in 2001 with the first recommendations for a comprehensive palette of outstanding plants for the maritime Pacific Northwest. No wonder this cardoon has such a fascinating and an exotic look to me. I do not garden in the Mediterranean, or in the Pacific northwest.
Silver leaved plants are not coated with some natural form of metallic silver. Many of them have leaves which are covered with very fine hairs that reflect light. That reflective quality makes the leaves appear silvery. According to the Plant Delights website, “The silver color is not a pigment, but rather some type of mechanism that scatters and reflects light. Some plants with silver foliage have a thick coat of foliar wax. Others are covered with fine hairs. A few silver perennials get their luster from blisters that separate the outer and inner cell layers of the leaf.” Silver leaved plants by and large hail from regions that are very hot and dry. That silvery surface is an adaptation – a means by which the plants can survive high heat and drought. Though I garden in a zone which gets regular rain, and infrequently has temperatures over 90 degrees, I love the look of silver leaved plants. This year’s window boxes at the shop-a celebration of silver leaves.
In the window boxes this year, I have planted artemesia “Valerie Finnis”, a blue/silver eucalyptus whose name I do not know, Cirrus dusty miller, a lavender with silver leaves, kalanchoe “Flapjacks”, the trailing artemesia “Silver Brocade”, an unknown silvery white succulent, and artemesia absinthium-or wormwood. I think I have identified these accurately, but maybe not. My knowledge of the names of exotic plants is sketchy. I was not shopping names for these window boxes. I was shopping color.
Some of these plants might be hardy in my garden, provided they were planted in poor, gravelly, and fast draining soil. Others are strictly seasonal for me, as they would only survive the winter in a very mild climate. Some would thrive and return the following year, only given the absence of a winter.
I am not generally drawn to succulent plants, only because they seem so out of place in a Michigan garden. But my container plantings can be comprised of any collection of plants that interest me. The best part of a seasonal/summer container planting is that I am not restricted by what would survive my winter. Most of the annual plants I use in containers come from tropical regions. I do use perennials hardy in Michigan in containers, provided their habit, texture, form and mass is such that they will look interesting all summer long. A columbine, or lupine in a pot has a very short season of interest. The coming of the hot weather – especially the hot nights – takes a toll on them. The tropical plants can handle the heat, should it come.
As long as I have been gardening, much has been said about the hardiness of lavender. Early on, I planted no end of so called hardy lavender, without much success. My longest relationship with a lavender plant-4 years, and 3 winters. Hardiness is not exclusively dependent on winter temperatures. My area is known for its heavy clay soil. Lavender likes perfect drainage – light soil. Drainage is a surprisingly big part of winter hardiness. A new lavender from Peace Tree Farm shows a great deal of promise. From their website: “One of the hardiest lavenders seen throughout Europe and the United States, ‘Phenomenal’ has exceptional winter survival, as it does not have the winter die back that other varieties like Munstead and Hidcote commonly demonstrate. Lavender ‘Phenomenal’ has also shown tolerance to extreme heat and humidity, and is resistant to common root and foliar diseases. Most commonly popular for its silvery foliage and consistent growth with uniform, mounding habit, ‘Phenomenal’ has an elegant flower presentation and fragrance, perfect for fresh and dried arrangements and oil uses.” Hmm. I will have to buy some plants. What summer garden seems like a summer garden without lavender?
For the moment, I plant lavender in containers, never expecting I could plant them in the ground in the fall, and winter them over. This silver leaved plant is just as Mediterranean in its roots as the cardoons. I am happy to have them, one season. Lavender seems very happy, planted with other plants of like persuasion. The range of silvery colors from bright silvery gray to silvery blue gray in this iron cistern all seem visually compatible. I suspect all the plants enjoy the heat absorbed by the cistern.
Proper watering will be key to their success. At Detroit Garden Works, we group all of the silvery leaved and succulent plants together on a table that is a do not water zone. Euphorbia “Diamond Frost” will deteriorate quickly from too much water. The leaves of helicrysum-licorice-will pucker and decline from too much water. Water the silver leaved plants as infrequently as possible, and then some. Your restraint will reward you.
Some of our echeverias only get water from the sky, when it comes. Otherwise, nothing, and certainly nothing from the hose. It may not have been the best year to decide to plant a collection of silver leaved plants. We have has lots of rain, dating back to early spring. Today, it rained all day, and it looks like it will continue to rain all night. My magnolias and parrotias have that lush green tropical look about them. The high temperature today-59 degrees. Not exactly Mediterranean.
Silver, blue, and gray leaved plants are beautiful in containers. The teucrium fructicans, or silver bush germander, in the center of this container, was lovely all summer long. I wintered it over indoors successfully for 3 years.
Plectranthus “Silver Shield” makes a beautiful seasonal groundcover. This small bed on a pool terrace is hot and dry in the extreme. I have never been able to get a perennial groundcover to winter over in this spot. The silvery gray is so beautiful with the pale pink roses, and white washed wall.
Some silver leaved plants do well in the shade. This silvery green begonia with silver blotches is underplanted with Shadow King gray begonia, and Pilea “Silver Tree”. Pilea “Silver Cloud” is equally as lovely. Silver leaved plants-I am happy to have access to them.