Garden Color during the Dog Days

By Kathy Conner Cornell VCE Southside Master Gardener About this time every summer our gardens are often looking as wilted, as we are if we spend any time in the heat. We often think of this time of summer as the Dog Days when the weather is hot and humid and often dry. This period got its name from the dog star Sirius which not counting the sun, is the brightest star in the sky. It is part of the constellation Canus Major, the Bigger Dog. Typically this time of year Sirius rises in the southeast horizon just before the sun. Regardless, we all know it has been hot, humid, dry, and dogs are lying around panting, until tropical storm Isaias showed up. 

The flowers of Sedum x ‘Autumn Joy’ start out white but turn rosy pink.  The rusty seed heads will persist through the winter and are good food for the birds. 

  Our gardens don’t have to look worn out if we landscape with plants that can stand up to the heat. One shrub that blooms in late July to mid August is Blue Mist Shrub, Caryopteris xclandonensis. It is a cross between C. incana and C. morgholica. A very popular cultivar is ‘Longwood Blue’ which is what I have growing. It doesn’t like excessive moisture and fertilization will cause it to grow rapidly and become leggy. They do need full sun and are fine with our soils. Flowers are borne on new growth so it does well with a hard winter pruning, back to the ground is not uncommon. The leaves are fragrant and because it is blooming when no one else is having a party, it is much appreciated by bees, butterflies and other beneficial insects. After flowering little green berries are formed. I admit I have never seen a bird eat them but then I had not seen a bird on my beautyberries until last winter. A mockingbird decided they were his favorite treat. 

 Lavender cotton, Santolina chamaecyparissus, is an evergrey perennial. Its fragrant silver foliage always looks great. It is a short plant 1-1/2 to 2 feet so it good as a border plant. The plant has small yellow button flowers in August. My perennials instructor Michael suggests removing the buds before blooming because it makes the plant fall apart. In ‘Herbaceous Perennial Plants’. Allan Armitage says the blooms take away from the foliage and serve no useful purpose. Not sure the bees would agree. He also suggests to keep it from becoming woody, it should be pruned hard after flowering. Pruning in the winter will cause death and I can attest to that. Santolina is very drought tolerant and wants full sun. Missouri Botanical Garden Plant Finder says it has a problem with humidity because of fungal diseases but this has not been my experience. 

 There are many Sedums out there but a favorite of mine is ‘Autumn Joy’. Its rosy pink flower heads are very showy. I remember this Sedum from my youth but the flowers were pink. I like the deeper color better. After blooming rusty seed heads form that are winter nourishment for the birds. This sedum is pretty much happy wherever you place it, does not like being fertilized and will become floppy in overly rich soil. It is fine with moisture but is drought tolerant. ‘Autumn Joy’ has a long season of interest emerging in March and sporting the seed heads through the winter. 

 Russian sage Perovskia atriplicifolia, has nothing to do with Russia or sage although both are in the Lamiaceae family. In “Herbaceous Perennial Plants” Allen Armitage states that during his college days they used to joke that the common name came from the smell that was like that of the feet of Russian soldiers. Can’t say I have any experience with that odor but I find the fragrance of Russian sage very pleasant. The light blue flowers form in late summer. Armitage suggests that the plant does not like heat and humidity but I have not that to be the case. He also doesn’t like its floppy habit but that works in my very informal garden. Russian sage wants full sun and good drainage is important. 

 Lastly I will mention a plant that I have had no success growing in my own garden. Butterfly weed Asclepias tuberosa is a beautiful late summer bloomer. I enjoy watching the bright flower heads of the plants growing in our hay fields. They have a long tap root so I would be totally unsuccessful trying to dig one up and placing it in the garden. In the hay field, Butterfly weed gets no special care except being mowed twice a season and getting rolled into hay bales. Still it comes back year after year. If you decide to give Butterfly weed a try, get the smallest plant you can buy or try seeds. It doesn’t like to be moved so be sure to place it where you want it to live. It is slow to emerge in the spring, patience is required. After flowering, milkweed pods will appear. Supposedly the seeds are easy to root. My husband and I often see the “fairies” from the pods flying around and I always hope that one will land it my garden. It has yet to happen! 

 These plants are all drought tolerant and put on a show during the Dog Days of Summer. The best part is that they are low maintenance and will look colorful without any help from you. In turn, you can watch the beauty from the comfort of your air conditioned house when temperatures outside are steaming.

 hile we are all still practicing ‘social distancing’ due to COVID-19, and all Halifax County buildings are closed to the public, if you have gardening questions, you can best reach an Extension Master Gardener or Extension staff member by sending an email to If you can’t email, you can call and leave a message at the Extension Master Gardener Help Desk at 434-830-3383, giving us your name, telephone number, and nature of the call. The Help Desk phone is checked timely and someone will get back to you, although it may be from a different telephone number. Keep washing your hands, wear your mask and plan to use some heat tolerant plants so you can enjoy the Dog Days of Summer.