Rose Care - June, July, and August -- It's HOT MAN!
If you are in cooler parts of Arizona, go ahead and continue fertilizing as you have. Temps in the 70’s, 80’s, and even low 90’s allow you to fertilize as regular.
*****
There are a couple of routes you can take, if you are in the HOT desert.
My Route: I stop fertilizing all together. Most roses in our extreme heat tend to go into a type of hibernation. You will notice that many of your roses are, or will, start to set hips. Much like they do in fall in cooler climates.
When your roses set hips in the fall, in the cold climates, do you fertilize? No. So why would we want to fertilize when they are setting hips in summer? If you continue to fertilize your growth will be rapid, lanky, and new growth may suffer severe sunburn. Your roses will have fewer petals, hybrid teas sometimes almost look like single petal roses.
Another Route: If you must fertilize, sometimes it’s hard not to, I know, always fertilize at half the strength you do during the cooler months. Or, another great way is to use time released fertilizer, like Osmocote. I prefer the Osmocote 14-14-14 time release fertilizer. I do use it in my potted roses all summer long, because it’s released slower, and fertilizes every time I water, without hurting the roses.
*****
Do, water. Roses are thirsty, and need water. You can’t water them too much in the summer. I have one bed of roses in the front yard that surrounds my entire front yard. In this rose bed, I use bubblers, because of all the other perennials and bulbs that are in that bed. I water once a week, and fill that bed with water.
The rest of my roses are drip irrigated. I use drip nozzles you can adjust up to 10 gallons an hour. In the summer, with drip irrigation, I water my roses three times a week (Monday, Wednesday, and Saturday), and they get 4 gallons of water, each watering. That takes me about 3 hours per watering.
How can you tell how fast your drip lines are watering? Take one of your nozzles and stick it into a gallon jug. See how long it takes to fill the gallon jug ½ way full. If it takes 15 minutes to fill it with a ½ gallon of water, it will take 30 minutes to fill the gallon jug, and 2 hours for 4 gallons of water.
If you have roses in pots, they must be watered 7 times a week, depending on the location, maybe even twice a day. I don't recommend pots in full sun in our desert. It's just too, too HOT!
*****
Keep your roots cool. Mulch, mulch, mulch those roses, with a deep layer of mulch over your top soil to keep the rose roots cool. Your roses will thank you for it. I put about 4 inches of mulch over the top of my rose beds every other year.