Rose breeding in hot humid climates

Hi all I have grown roses in South Florida (USDA zone 11) on and off for about 15 + years and am interested in developing roses particularly suited to our climate (Hot & Humid). I have been reading the postings concerning breeding back to species roses in the hopes of establishing lines that will help to impart vigor. Does anyone have any suggestions to that respect as I do not know of any species commonly grown by rosarians in this area. So far I have been looking at crossing HBTs with the handful of roses that seem to be the most carefree growers in our climate such as: Luis Philip, Old blush, Champnys pink cluster & Mrs. Dudley Cross in order to add those genes to the mix. Also I have some experience working with orchids and was wondering if anyone plants their seed in vitro as a way of getting the seedlings past the most susceptible damping off stage. All suggestions will be greatly appreciated.

Hi fred,


The Link may be of interest.



Fred, what do you mean when you say ‘in vitro?’ Do you mean while still in the hip? Generally, it’s said that the pulp discourages germination.

Ah, I think I read that wrong… do you mean removing and just planting the embryo or germinating the seed in a petri dish? Please explain. If the later, I do do that and have little problems with damping off, though mold on the seed can be a problem.

I’ve tried germinating roses “in vitro” (in tissue culture), but it’s quite difficult. Without removing the seed coat there are fungi that get into the media even with surface sterilization with bleach. It is very difficult to remove the hard pericarp without damaging the embryo. In fact, even with immature seed, not long after pollination, the pericarp is hard and difficult to remove as well. The French research group that generated haploids (2x) of 4x cut rose cultivars used embryo rescue and had difficulty with the pericarp on immature seeds as well.



Hi all Firstly I want to thank you all for the great responses to my posting. I know I am going to get a lot out of this membership. As far as “in vitro” what I was referring to, was planting the seed in a nutrient agar medium within an enclosed test tube. This would of course involve sterilizing the seed and working inside of a sterile environment. When working with orchids I usually surface sterilize the seed with hydrogen peroxide as I found that I tend to kill seed when treating them with the bleach solution directly (phalenopsis seem to be particularly sensitive in this respect). I have not done any tissue culturing as of yet but have been reading up quite a bit on it with the hopes of eventually trying my hand at it. For those of you that are interested in tissue culture the attached link has an online group related to it that discusses ways of adapting the techniques to home gardeners. From what I understand tissue culture has not been the boon to rose growers as it has been for other plant enthusiasts. However I am not enough of an expert on the subject matter to give a real opinion.



As David has pointed out, you are going to have great difficulty in sterilizing rose seeds for in vitro culture. Contamination will be a huge problem. I have also done flasking of Orchid seed and it is a much easier thing to keep Orchid seed clean in a sterile flask. In vitro culture of rose seed will offer you no real advantages, I believe, since rose seed is so easy to geriminate in soil.

As for appropriate cultivars to breed for hot climates, your descision to work with the everblooming CVhinas is a good start, for sure. I would also strongly encourage you to work with the Teas and Modern Miniatures. Why Miniatures? Because the vast majority of these were bred in the Central Valley of California where heat is nearly ever-present. They know how to grow in hot climates. They also have an important genetic advantage: they will help keep the size of the progeny down, since the natural inclination of roses hybrids is towards large, climbing plants. Restricting size of the hybrids you create would be important in a climate like yours, where rose sare going to tend to get very large and overgrown.

As for the Teas, I cannot emphasize strongly enough what a wonderful parent ‘Mons. Tillier’ has been for me the past two seasons. It can produce the most exquisite offspring. I would think this would be a valuable rose to include in any hot climate breeding program.



What I have gathered about tissue culture is at the following link:

I have not done any tissue culture lately as I have enough promising breeding lines going to occupy the time that I am able to devote to rose breeding.