Rosie’s Corner: Help roses weather the high summer heat

Jul 1, 2024

Well, you can tell it is July in Fresno! Like the song says, “The heat is on!” The only consolation is that this too shall pass (in a few months). The heat takes a toll on your roses (and you too!). I will be sounding somewhat like a broken record (is there still such a thing?) over the next couple of months. The high summer temps are less than ideal for having beautiful roses. Check your garden in the morning when it is the cooler part of the day. Look at the leaves of your plants for leaf wilt, drying or discoloring of the leaves. If they appear dull, check your plants for disease, drought or pests.

Now is not the time to fertilize. Your plants are struggling to remain hydrated. You can remove your withered petals and let hips develop for the time being. Make sure your plants have at least 3 to 4 inches of mulch around the dripline of the plant to help keep away weeds and help to maintain moisture. 

When temps get over 90° F, roses will lose moisture through their leaves. This sometimes shows up as browning along the edge of the leaf. Insufficient moisture in the root zone of your roses will cause this. It is a sign of heat stress. Make sure you give your plants adequate water on the days when we can water. If you see this, don't be tempted to remove the leaves. They will help the canes of the plant to stay shaded from the sun and not get sunburned. Sunburned canes can kill your plant.

If the edges of the leaves of your roses are crispy dry, they are sunburned. It happens here in Fresno this time of year. What causes this and do you need to cover your leaves in sunblock? No to the sunblock. Just make sure you wear it when you are in the garden. What causes sunburn on the edges of your leaves is that we have various salts in our water and in our soil. According to Curtis Smith, retired New Mexico State University Horticulture Specialist, the rose plant will take up those dissolved salts to the leaves from the roots during transpiration. As the water transpires from tiny pores in the leaves, the dissolved salts are left behind. The salts left at the leaf margin kill the plant cells in those spots when they get to toxic levels. This causes the leaves to look burned and can also cause a crusty white build up on older leaves.

So, is there a way to fix this? Make sure you water deeply (see Rosie's Corner for June 2024), to help push those salts down through the soil profile and away from the roots. Don't over fertilize with inorganic fertilizers, which are made up of salts. Use mulch to conserve moisture and it will help to keep the soil temperatures moderate. However, once a leaf is burned, it will not green back up. Best to be patient and wait for new green leaves to emerge when we deadhead again in cooler weather.

Again, check your plants for any signs of pests. Thrips and spider mites love this time of year and these temps. A strong spray of water below the leaves, followed by an overhead shower can help to keep those little critters away. Do this early in the day, on the days you can water, for at least 10 -14 days. Inspect your plants daily for any signs of infestation. A bonus is walking in the garden, a great way to reduce stress. (Did you know that in England, physicians can prescribe gardening as a treatment for reducing anxiety and stress? Scientists have found spending two hours a week in nature can lead to better health and well being.)

So, on that note, it is important for you to take care of yourself when you are in the garden. Work in the garden early in the morning and use proper, sharp and clean tools. Wear long pants, long-sleeved shirts and covered shoes. Shorts and swimsuits don't give skin protection and sandals, or bare feet won't protect your toes from dropped pruners. Use sunscreen when you are outside. A broad brimmed hat or a hat with neck protection will also help. Drink water before and after working in the garden to keep yourself hydrated. 

Dainty Bess Rose

This is one of my favorite roses. It has ruffled pink petals that surround maroon stamens. Those open blossoms allow our important pollinators to enjoy the rose as well. This is one tough rose, named in the 1920s after Bessie Archer, the wife of breeder William Edward Basil Archer of England. Archer was a furniture designer, but bred roses as a hobby. He and his daughter, Muriel G Archer, sold roses from the 1920s to the 1940s in Kent, England. As a rose breeder friend of mine said, “You don't name a bad rose after your wife if you want to stay married.” Dainty Bess is a great rose! She is a hybrid tea and comes as a climber as well.

picture of Dainty Bess rose pink single with ruffled edges
 
picture of Dainty Bess pink single rose with ruffled edges

(Photos: Wikimedia Commons)

Until next time...”It's OK to feel delicate sometimes. Real beauty is in the fragility of your petals. A rose that never wilts isn't a rose at all.” - Crystal Woods, Write Like No One is Reading