I hope this helps!
1. When is it appropriate to use fungicide/insecticide? What situations would call for the use of them?
I have a no spray garden but when I did spray I only used insecticides when I saw bugs and could ID them properly. Fungicide spray programs should be started early, before you even see symptoms, for best results.
2. What about homemade pesticide/fungicides, when is it appropriate to use them? (apple cider vinegar, baking soda, garlic powder, etc. etc.)
It's up to you if you want to try home brews or not instead of store bought chemicals. I've tried many of them and have found they don't work all that well most of the time. I would also caution you against using anything that contains any kind of oils. Often they just burn the leaves, especially if it is hot and sunny.
3. What fungus/pests/problems should I look out for in SoCal and/or Central Valley? How should I deal with them if they come up?
I'm in Michigan so I can't really advise you on this but I do know that black spot is not as prevalent there and rust is more so. In 15 years of rose growing in Michigan I've only seen rust twice but black spot is an everyday battle. I'm pretty sure powdery mildew is something we do share as well. The best defense is to look for roses that are naturally resistant but otherwise you either spray or learn to live with it.
4. In regards to root damage, If the roots of roses are damaged in repotting process or stuff like that, what course of action should be taken? (can't find much into on this on the internet)
Transplanting potted roses is much easier than roses in the ground. As long as you do not disturb the root ball at all they should be fine. In potting up a rose just slip the smaller root ball out and slip into the larger pot or ground hole and back fill. In the ground, no matter how hard you try, you will damage some of the small feeder roots. But just try to take as large a root ball as you can and keep it as intact as possible when you move it from one spot to the other. It may suffer some transplant shock but as long as you keep it well watered it should recover. Do not fertilize it until you start to see new top growth!
5. What are general tips you have about potted rose care?
- Should I mulch potted roses? How about Miniature roses?
Use any good quality POTTING soil. Never use garden or top soil in pots. Make sure the pots have a number of drainage holes. Good drainage is very important in pots. Pots will generally need watering more often than roses in the ground because they dry quicker. Potted roses will also need fertilizer a little more often as well. Every time you water a pot you flush some of the soil and nutrients out. So extra fertilizer is helpful. That does not mean a stronger solution. It means more often. A stronger solution may burn the roots. Miniature roses should be treated just like any rose. They require no special or different handling.
6. How about tips about general rose care?
Roses are perennial shrubs. They require the same things that most perennials do, good soil, adequate sun and water and a good pruning about once a year. Throw in some fertilizer now and then and they should be very happy.
7. Should I use a sealing compound when doing any type of cut on roses?
You only need to seal any cuts to canes that are larger than a pencil. That is to keep out boring insects. Borers can not bore into any canes smaller than that. You can use anything that is water proof. I've used Elmer's Wood Glue, clear nail polish and wax. But truthfully, I'm not very vigilant at it and have never found a borer in my roses. However, that might be location sensitive. I'm sure there are places where borers are a problem.
8. What are warning signs in a rose that something's wrong and what are some things that look bad but shouldn't be worried about?
There are obvious signs of fungal infections and insect damage. Yellowing leaves can be a sign of many issues like both too much and too little water as well as some nutrient deficiencies. But often times yellowing leaves may just be the plant shedding old, tired out and non productive foliage and is not any kind of problem. A yellow jagged or lightening bolt pattern on leaves may be an indication of Rose Mosaic Virus. A lot of roses in the US have this disease. It is NOT fatal and, for the most part, if the rose is well cared for and healthy, you will never see it. I have many roses in my garden that I know have the virus and some of them have been here as long as 50 or 60 years. And I'm in a cold climate with harsh winters.
If you have more questions please ask.
