The rose is rated to grow in zones 7 - 11. By that definition, it means that this particular cultivar is too tender to grow in zones 1-6. My suggestion to bury the bud union in the colder zones ( 7 - 8 ) is to protect the graft from freezing during the winter. If the ground does not freeze in your zone, you do not need to bury the bud union. Zone 9 is on the warmer end of the zone scale, so you should not need to bury the bud union.
There are a lot of right ways to grow roses. Also, each and every rose is different. Each zone has micro-climates. These are things you need to take into consideration. You may live in Zone 9 , but your garden may be at an elevation which makes it colder than temps reported for Zone 9.
I have some roses in my garden that I know are rated to grow in a colder zone, but I still buried the bud unions on those roses I know are tender. That is because I live in the mountains, and my rose garden is at the bottom of a slope. I know that cold air travels down the slope, so that part of my garden is colder than other parts of the property. It's not necessary, but it also hasn't hurt any of the roses I planted this way. I just happen to be cautious because I don't know when we are going to have a winter that is way colder than the norm. It's the only winter protection I provide for my plants. Other rosarians don't bother with this step.
I also am careful not to place plants near a wall that will reflect heat during the summer because we go through weeks of temps in the triple digits. I have found that I have less disease and insect problems this way, so I don't have any climbing roses growing up trellises next to walls.
Each gardener finds what works in their garden. As you garden, you get a feel for the space and placement of plants. You can follow other people's wise advice and the plants will just up and die on you. In my opinion, every rose you plant in your garden is something of an experiment. If you start with a rose that likes your climate and is healthy, provide sufficient water and nutrients, it should do well. Please note the word "should". Every gardener makes mistakes or has plants that do not perform as expected. As you have done here, you try to get the best information possible to give yourself a better chance of success.
If a rose doesn't do well for you, there are thousands of other roses to try. I wish you the best of luck.
Smiles,
Lyn, helpmefind.com
