My terrace apartment faces west and I was wondering what flowers would be good to plant in window boxes. The sun is very strong in the summer and I would like to know what flowering plants can withstand the heat and sun.
There are a number of annual plants that can handle strong sun and heat during the summer months, relatively pest free. The first that come to mind are petunias, especially the trailing varieties. These come in many colors, have a delightful aroma, and can tolerate drought.
Petunias can take the heat. White Flower Farm
It’s always a good idea to check plants in exposed window boxes daily during the summer to see if they need water. If they do, water them in the early morning, preferably before the sun hits them. Water around the base of the plants and avoid wetting flowers and foliage to reduce the risk of diseases and harm to the flowers. If you have used a potting soil mixture that contains fertilizer good for three months, then there’s no need to add a soluble fertilizer to the water every other week or so.
Zonal geraniums are available in deep red, light red, white, salmon, and magenta, and tolerate heat and drought very well. If you like oranges and yellows, marigolds might work for you. Celosia, or cockscomb, provides a plumed or crested look as well as color (pink, red, orange, yellow) for your window box.
Dwarf zinnias, which are multi-colored, thrive in heat, but bloom later in the summer. There is also the moss rose (Portulaca grandiflora) in red, rose, orange, yellow or white —they are drought tolerant and low maintenance. Dusty miller, a silver-tone grown for its foliage, sweet alyssum with small white flowers, and blue salvia are other possibilities.
Why don’t you visit your local retail gardening spot to see which of these plants appeals to you and what colors you’d like to use? Depending on the size of your window boxes, you might want to combine some of them for more eye appeal, being careful that you choose plants that mature at 12 inches or less and that their watering requirements are similar. For example, zonal geraniums and portulaca can handle dry soil for several days (but would perform better with regular watering in hot weather).
For more information on plant selection, contact your local Cornell University Cooperative Extension.
Mary Ann DeRosa, master gardener with Cornell Cooperative Extension of Westchester