It looks as though our run of a cool and crisp (not cold) autumn are soon coming to an end. For weeks now, we have had bright, sunny days with daytime highs in the 60’s and nighttime lows in the 40’s and 50’s. I checked the long-term forecast last night and it looks like soon we will be onto the pre-winter days of Maine with highs in the 40’s and lows in the 20’s.
With the expectation of an imminent hard frost, I am preparing to say goodbye to one of our best annuals of 2013. For over 5 months, Plectranthus argentatus has pleased our staff and guests with its big, fuzzy, silver leaves. If you are not familiar with P. argentatus or silver spurflower, try to imagine a big, bushy, silver leaved coleus. As a matter of fact, this Australian native is a relative of coleus. They are both in the mint or Lamiaceae family.
We planted our silver spurflowers in early May from 4″ pots. As the temperatures rose, it filled in and bushed out until it reached over 3′ in height and width. Our plants are en masse along a walkway in our Rose and Perennial Garden. I know, it is neither a rose nor a perennial but it does provide a nice, soft edge to the path that is in part-shade. That leads me to culture of this plant. It will take some sun but does best in part-shade. Our plants receive mostly morning sun and then dappled light throughout the remainder of the summer days. Provide adequate moisture and nutrition or the plants will appear leggy, open, and stunted.
From a design standpoint, the big leaves are the perfect foil for other brightly colored plants. Salvia, verbena, and geraniums could be a few of the many brightly-flowered annuals that you would want to plant with this superb plant. If you have a greenhouse, you could even overwinter plants from cuttings or start plants from seed early in the growing year. We were extremely impressed at how this Australian native did in our coastal Maine climate. As we begin thinking of our bedding designs for 2014, Plectranthus argentatus will surely be one of the go to paints in our colorful planting palette.