By Stan V. Griep, Consulting Rosarian, American Rose Society – Rocky Mountain District, and Member of the American Rose Society, The Loveland Rose Society and The Denver Rose Society Photographs courtesy of Stan V. Griep
The month of July in our rose beds is a time of maintenance for our rosebushes. We need to make sure that our rosebushes are well watered as the temps can get pretty high, not just of a day or two but strings of days. Several days of over 90 degree heat and even the lightest of breezes will suck the moisture out of the soils quicker than we can believe. Thus we need to be vigilant and check the soils moisture around our roses, plants, shrubs and trees more often.
This month is also when many rosebushes throughout the USA get to be very dense with foliage. The foliage being too dense can lead to some problems. The dense foliage does not allow the air to circulate well through the rosebushes, thus it is possible for them to get overheated on those strings of hot days. Foliage will start to turn yellow and the leaves will start falling off of the rosebush even though we have fed and watered them well. The rosebushes start doing their own thinning process as a way of keeping cooler. Some of our rosebushes will go into a bit of heat shock and stress and will make a major move towards dropping leaves, the leaves will turn yellow pretty quickly and fall off.
This can send the rose loving gardener into a true tizzy or tailspin so to speak! I have overheard folks at garden centers talking about it and asking the garden center staff what spray they can use to stop it. Many times a combination insecticide and fungicide spray is recommended. Since the real problem is unknown, it is not wise to immediately spray the rosebushes with any harsh chemicals. Spraying them with some chemicals can actually compound the problem since they are already in a state of stress and shock. Always take a good look at all the foliage, both top and underside of the leaves. Look for small bugs or even egg deposits, look for the typical fungus signs. There are great photos of the various funguses on-line and in rose care books to guide us.
Doing a thinning out pruning of our rosebushes will help them to avoid some of the actions the rosebushes will take on their own if we do nothing. Take a look well into each rosebush that appears dense with foliage and prune out some of the smaller canes or some of the branches coming off the large canes to help create some air circulation space. You do not need to thin so much that the nice rich looking foliage of your rosebush now looks far less attractive, just a little bit here and there goes a long way to allowing proper air movement for cooling.
Another thing we can do to help our roses deal with the heat is done at watering time. Watering either early morning, or early evening once the temps have started to drop off and the intense rays of the sun have tamed down, are the optimum times to water the roses. At the same time give the roses foliage a quick rinse off with a watering wand. The rosebushes not only enjoy the cool shower but it also washes the foliage to help remove some dust and fungus spores. The cool shower also opens the pores on the leaves so that they can do their part in keeping cool and nutrient processing. After rinsing the foliage off during an early morning watering, I will lightly tap the canes or foliage to help knock off any little pools of water on the leaves.
There is an old long standing thought out there that you should never get water on the rose’s foliage and especially never ever get water on them in the evening. While rosebushes that are left with wet or damp foliage and damp conditions for several days can lead to a fungus attack of one sort or another, the rinsing off at times of watering is not the same extended wet or damp time needed to get such attacks going. After all, what rose loving gardener can stop the rainfall? It can rain early in the morning, mid-day and evening. Some evening rains can be quite heavy and leave droplets of water on the foliage that lasts well into the morning hours. Thus it is more of a myth than a truth to be sure. Give the foliage a cool rinse; the rosebushes will truly enjoy it.
Should you notice that your rosebushes are dropping foliage in times of high temps, you can give them a tonic mix that will help them deal with the heat stress and shock (this works well at times of planting and transplanting too.). In a large watering can mix a root stimulator product and a product called Super Thrive into the same water together per the label instructions. Water the rosebushes with this mix the next 3 to 4 times they need water. It will give them a boost in dealing with the shocks and stresses that they are currently presented with.
We all love a good fireworks display here in July, so be sure to take some time to sit back and watch the grand display of bloom smiles your rose beds are placing before you! It is good to take time to relax and enjoy the beauty of our labor in the gardens, there are some pretty spectacular shows in our gardens and they last longer than a fireworks display too!
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By Delilah Onofrey, Suntory Flowers
Photographs courtesy of Suntory Flowers
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