Question

JFK   QUESTION: My garden is in Colorado. My soil is clay with carbonate. In preparing the garden and planting the roses I hit a hard pan near 24". I have composed for 20 years.  I've had these roses in my garden 10 years:  JFK, and Ingrid Bergman (Poulman).  My fertilizer contains a systemic pesticide. I drip irrigate.  My problem is that the JFK buds have a dead and brown edge on the petals and the buds do not open. The buds are prolific and on stems 24" long. The Poulman once had black petal edges but with the systemic seems to have resolved this problem but the stems seem stunted now where they grew 12 to 15 inches before. The roses are in full sun ). This is a vegetable garden but the roses have their own raised plot that also contain a few mums.

ANSWER: Both of your roses are good ones with a long history of doing well. In your garden they really shouldn't cause you any major problems. If you hadn't mentioned that you use an insecticide I would have suggested that the problem with JFK was rose midges as they kill or damage the rose buds which means the bush produces brown or dead blooms.Thrips like white roses and they cause the brown flowers. Thrips are also VERY hard to get rid of even with insecticides. Black edges on Ingrid is not unusual for this rose or for that matter on most deep red roses. Their petals will burn with sun. However when a rose has stunted growth  then there is something going wrong with the roots. I should also mention that constantly applying a systemic pesticide can in time, cause problems with certain roses. An insecticide is a very strong chemical and really best used when insects show up. The combination of the sun's heat on the sap which has this chemical in it, has definitely shown in time to damage the rose bush. Is it possible that the soil is too alkaline?
I would stop the insecticide for next spring and see if there is an improvement due to the fact that they are older roses and may have become sensitive to the chemical. Also check JFKs buds and see if there is a tiny pin hole at the base of them. If your Ingrid Bergman still has stunted canes next spring, then there is a serious problem with the roots and it would be a wisdom to have the soil checked.

---------- FOLLOW-UP ----------

QUESTION: Thank you for the thoughtful answer. I have been concerned about the calcium carbonate (hard pan)at depth.  Because the soil was so poor when I developed the garden from a lawn, after composting for several years, I sent a mixed sample from throughout the garden beds to the Colorado Agriculture Dept. who preformed a soil analysis; pH (7.5), salts (0.4 mmhos/cm), lime % high, organic matter (5.2%), N (23 ppm), K (444 ppm), Zn (5.7 ppm), Fe (13.4 ppm), Mn (12.9 ppm), Cu (2.5 ppm). I'm a chemist but not a soil scientist and less of a botanist!  They said no fertilizer was recommended.  Do roses like acidic soils? Yes my soil is alkaline. Just for clarification since we were using different terminology : I used calcium carbonate which is lime (Ag Dept)  and both are alkaline. Please forgive me if I stated the obvious.
I have been concerned with drainage and over watering because of the hard pan at depth and clay. The drip system is set for 20 min, two to three times a week depending on month and two 2 gal/hr drip heads. Yes I the roots are a concern of mine.  If it is the soil, can I safely dig up the rose and change the soil by bring in new soil?
I agree that the intense sun and heat may be a problem.  The vegetables have problems in July.  I have noticed occasionally that a few leaves get a dry edge that looks  burnt. But this improved with the systemic  which I have only been using for a couple of years. But as you recommend, I will not use this pesticide next year to observe any changes.
Buds don't seem to have pin holes at the bud base except for one bud. They look health except for the brown edges but they never open. I clipped one that hadn't turned brown and brought it into the house. Put it into a vase and physically opened it. Of course it looked a bit unnatural but did last several days.  I have been reading about Thrips. They do seem to fit the description of my problem. I will be very observant next spring.
How close to the rose can I plant other flowers like my mums?
Thank you again for your answer. This is a wonderful service. I appreciate your time, interest and expertise!


Answer
Let me start with the obvious first in that your soil may be too alkaline for roses to grow well but you do have clay which they love. Roses prefer a ph of about 6.5 or a little higher but not lower. Most roses require a minimum depth of 18 inches for their roots but preferably deeper. I find that most gardeners try to turn their garden soil around to suit the roses. Roses can adapt to many types of soils and you can change an alkaline one. Constantly putting in different chemicals in the form of fertilizers plus amendments in the soil just means once you start you have to keep it up as the rose gets use to them. Plus they will in time change your soil ph. It is a wisdom to start with the correct ph and good drainage, then add  organics on top around the base of the rose bush. I am not an organic gardener but roses like to slowly consume nutrients and organics gives them a slow release. If your soil is not perfect, then chemical fertilizers will throw it our of whack very quickly. Although the rose does not discern between the different forms of chemicals such as organic or chemical, the soil does. Bought soil is always part sand as they have to add sand to get it through the screens they use.If you want to replace your soil, then do it in the early spring when the roses are dormant and don't mind being dug up. Cut them back to 12 inches and replant. Plus water well the first few months because of the transplanting.
Roses do not take up any nutrients until they have been broken down in a form they can use. Micro bacterial do the job and they take about 6 months to break down the organics. Probably because they are unionized! So because of the later, they will not tolerate harsh chemical fertilizers as the chemicals will kill them. Then you are left with a rose that appears to be doing well as the nitrogen is the only part of the fertilizer they can use with the help of the bacteria. As nitrogen activates growth, the rose appears to be growing with vigour. A few years of chemicals and it slowly starts to decline because the soil is now right out of balance. It is not the rose you should be concentrating on but the bacteria in the soil. Once you make them happy, the roses will do well for you. Liquid fish fertilizer is their nutrient of choice and roses also like to have it as a foliar spray. However if you are committed to chemical fertilizer, then the slow release Osmocote 14-14-14 will do you for all of the season. I use in in my container roses and it appears to keep them growing very well. The bacteria require an acid soil with some sort of material dug in for drainage and a wood mulch placed around the base to keep them plus the roots damp and cool. In regards to water. Roses again prefer to have once large gulp of water rather than many small sips. You should , under normal weather conditions, only have to give them a bucket of water (4 gallons) every five days, more or course if the weather becomes hot, then every three days. I will leave that amount up to you as you know how fast it drains. If it takes a whole day then that is okay. Roses once established are very drought tolerant so going a few days without water won't hurt them.  Constant watering only encourages the frail feeder roots to grow closer to the surface which you don't want in high heat. The other long roots are mainly anchors. Just for your information, I too have a drip system and have been warned about using it to deliver any chemicals as they can plug up the line or even the nozzles. Again I would back off from the insecticides, as a chemist your hair will stand on end when you read about the chemicals used in them and they also corrode a sprayer.
In regards to the lime. I am assuming you are using the horticultural type or the Doperil. Both are really not needed for the roses but I am sure that certain root vegetables do better with it.
Mums thrive in well-drained soil with lots of water but with excellent drainage. They will no tolerate soggy soil. You need about 12 inches of perfect conditions as they are shallow rooted. And because they are shallow rooted, they will not tolerate any competition. But roses also don't like anything except shallow rooted plants around their base. Plus when you fertilize the roses it may not be what you want for the other plants. I grow the exhibition type mums and they require loads of attention plus nutrients and constant water so they won't wilt, therefore I grow them alone. I wait until they are 18 inches tall and then I cut them down to get bigger blooms. They also do well on liquid fish fertilizer. Keep in touch if you need anymore information. Hope this helps.