I plan to try some greenhouse rose breeding this fall and winter.
I have 2 questions:
What is the ideal day/night temperature range to maintain in my greenhouse in order to promote the best hip set and ripening?
Also what is the LOWEST day/night temperature I can set and still get hips to ripen?
I would like to avoid spending a fortune on heating fuel.
I have looked online and can’t find any information on this.
Thank you in advance,
Cathy
Central NJ
I don’t know about in a greenhouse, Cathy, but here, when evenings are mid sixties and above and days are mid nineties and above. most roses ripen hips (brilliant colors and fall off) in less than two and a half months. What’s green today is brilliant orange the day after tomorrow. Between now and then I’d better pick it or it’s gone by the next day.
About the best I can offer is a paper by DeVries and Dubois in 1987, entitled “The effect of temperature on fruit set, seed set and seed germination in Sonia x Hadley hybrid tea crosses.” It appeared in Euphytica 36:117-120. In my review on the RHA site I give some info about how seed germination was affected. The optimum temp for pollination was 22 C, ripening happened faster or better at 18 C, while germ was best if 22 was used during development of the seeds A 4 month cold stratification at 4 C and germ at 22 C was used in the germ tests. Hadley was a really old HT at the time of this study, while Sonia was popular in Europe I believe. No idea why they picked this combo to test.
I would expect rather different results with some other CVs, but I think it is saying you need things pretty warm. Von Abrams and Hand back in the 1940s growing seeds outdoors found that later germ was poor if the seed ripened at a low temp of the last couple months. They studied quite a few crosses with prominent plants of the time. Afraid you’ll have to spend a lot on heat, or move in next door to Jim Sproul for the winter.
Here in San Diego County area the hips sure seem to cut down on time taken to ripen (turn color) when the heat turns up in late summer and early fall. But the speed of development of hips (which I am equating with the growth of seeds) seems to vary a lot from rose to rose. Some roses seem to fully develop their seed very fast in late spring while others show faster hip growth in late summer/early fall. I have several roses side-by-side that were pollinated within the same week 3-4 weeks ago and on several of the shrubs the hips are already full size whereas on the others they are just developing. From this I would think that there would be some roses that would be more successful in a moderate greenhouse, and others that would be more successful in a warm green house. My late blooming wichuranas seem to ripen at almost the same time as the earlier blooming ones. The same for the acicularis hybrids, which span about 6-7 weeks of bloom but all seem to ripen at the same time. This is purely speculative, but it seems like the flowers are more fertile and set seed best without temperature extremes, but that the seed grows better and matures faster with a little more heat.
Thank you, Larry. I found that paper too. It was the only reference I could find.
Based on the responses to this post and that paper, I will set the greenhouse to 70 degrees F daytime and 60 degrees nighttime, and see what happens. The daytime temps will probably get higher, but that probably doesn’t matter as much as the nighttime temps.
Thank you very much for the reply.
Cathy
Thank you Jackie. I will be using relatively modern roses like Mister Lincoln and Alec’s Red. I ordered around a dozen fragrant, high petal count hybrid teas and potted them up. This will be my first time trying to pollinate indoors during the winter. I will treat it as a learning experience and keep my expectations low.
My greenhouse is a small commercial greenhouse. My late husband and I ran a perennial nursery on our property for many years. And Garth and I were fortunate to observe Frank Bernardella’s GH set up for his minis because he lived a few houses down from us. Of course, my entire HOUSE could have fit into Frank’s greenhouse… LOL
Regards,
Cathy
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You are going to face a real challenge keeping the likes of ‘Mister Lincoln’ free of mildew in the confines of a greenhouse, especially during the dark days of winter. Good luck!
Paul,
Could she use lights to supplement during the dark days of winter?
Joan
Looking at where you are I wonder why you feel a need to move your breeding activities into a greenhouse. As cold as it gets here (-12 degrees F some years, usually -5), about the only use I would have for a greenhouse would be to keep very tender breeders and seedlings from freezing in the winter, and to keep fresh pollinations dry for a day during the hybridizing season.
Your winters don’t get cold enough for long enough that you need to worry about most of the classic HT’s surviving.
Your summer is plenty long enough to overfill the larder with hips without needing to extend it at either end.
I realize this is your first year and you want to speed things along with your greenhouse but choosing some new breeders and propagating them over this winter might be more efficient in the long run than indoor hybridizing.
If you were to decide to work with species roses your greenhouse would be invaluable to overwinter the first couple of generations of crosses against very tender partners because such progeny tend to be tender themselves. It would also allow you to stable some of the species that need winter protection like roxburghii, wichuraiana, chinensis spontanea and gigantea.
Mister Lincoln is very woody for an HT and it actually likes a bit of winter. Despite it’s disease problems it has promise as a breeder for winter hardiness because it otherwise offers a suitable package of refinements - remontancy, poly-petally, petal size and substance, bright white parenchyma in the petals, fragrance, pigment density and complexity - and good fertility and broad cross-compatibility. For that reason it is also a good choice for pairing in species crosses and, in fact, is one of the few breeders I have had success with using moyesii pollen and pollen of Eddies Jewel (but not reciprocally, alas).
I’m reluctant to promote breeding with HT’s but you could consider using Tiffany, too, especially of you can find it VID, for the same strengths and with better fragrance but with the same limitations of disease and architecture. HT’s that are closer to the Pernetianas would give you greater pigment density at the expense of hardiness and the need for chemical life support but, again, if these were partnered with species roses then the compromises would be acceptable because the potential would be greater (imho): Soeur Thérèse, Pinocchio, Fashion, Spartan, Zorina.
Foundation breeders that would broaden your genetic base would be things like Joycie; Apricot Twist; Condoleeza; Dragons Blood; Sympathie; Robin Hood; Carefree Delight; Immensee and its derivatives; any of Griff Buck’s hybrids (getting to be hard to find); any Geschwind especially the setigeras (harder to find); Vielchenblau; descendents of McGredy’s Maxi; descendents of Horvath’s setigera Doubloons like Goldilocks/Allgold/Rumba (send me one too)/Watercolor; any Max Graf descendent of which Kordes has many; and Yellow Pages because it combines two important, relatively diverse lineages.
The strategy with these would be, of course, to target the usual physical refinements while selecting for disease resistance, vigor and hardiness.
Breeders that could be even more rewarding include the Barden Atomics - Castle Bravo, Canniken, Dakota Redwing and Diablo Hawk (Paul, what about Dominic Sunset?); Rupert’s Lynnie and his fedtschenkoana derivitives; Rippetoe’s bracteata’s; Harris’ R15-01 and derivitives; Davis’ Carefree Copper; Zlesak’s Oso’s; Sproul’s G-34 and I-89-2; and anything by Kuska that’s named after one of his relatives or comes from his giveaway seeds. Most of these are non-commercial, your mileage may vary.
Joan, this is central New Jersey. We have no DARK DAYS of winter.
We have winter days Jan-March when the daytime temps are in the 50’s and I can open up the GH to let fresh air in for several hours during the day.
Regards,
Cathy
Thanks, Don. Mr Lincoln is not one of the HT’s I am overwintering. I just used it as an example of a high quality HT that I am using in my breeding program.
And this is way not my first year of breeding roses. I started in the early 90’s but had to take a long hiatus due to my day job.
I bought a bunch of HT’s this summer that have already been delivered, and in my opinion will be too small to plant this fall. Therefore I will overwinter them in my heated GH and will plant them in the spring.
In the meantime, if I can do some pollination during this winter, well, I would like to try that.
I used Tiffany back in the early 90’s and have no interest in using it again.
Hi, Don. Virtually all of my breeding is with modern HTs. I am using a few really good Floribundas in my program with the interest in creating some interesting grandifloras.
I leave the more complicated interspecies hybridizing to all of you way more experienced breeders!
Regards,
Cathy
From my limited greenhouse breeding experience, I’ll share the following observations. I have made crosses until beginning of the new year, and ripened hips from crosses made before freezing outside. Things move slower but they do eventually ripen, and the seeds germinate. Bloom production is low, but isn’t dependent on day length for modern roses with the ever-blooming gene. Some roses more reliably go into rest phase, others into continual bloom under these conditions. The very best repeat flowering I’ve had is what used to be sold as LaFrance by a nursery in CA. I think it must be an old ( @1900-1920) greenhouse variety. Low light, low temps, blooms for Valentine’s Day.
My greenhouse is very small (9 x 12) mostly solar heated with insulation in place every night, kept above freezing by a single electric heater when nights are below freezing to 0 F range. With the wide range of temperatures, up to 80 F on some of our many sunny days, and lows at night above freezing, bloom production is minimal from Dec to Mar. But it does get a couple months or more head-start on anything growing under natural conditions.
How things do depends on the year. With a mild winter like 2011-12, lots happens, in others, not much. Mildew will be an issue when the days get warm while nights are cold.
I think your location will be much more cloudy, but tempered by the coastal effect much of the time. If there are people with high tunnel production facilities in your area they can advise on the solar gain vs heat input that they have experienced. Your photo suggests you have something comparable to work with.
The warmer you can afford, the better you will do.
Thank you for the guidance, Larry. I will set the nighttime temp to 60 degrees F. And I will open up the GH on sunny days to promote fresh air circulation. I will also spray the roses for black spot and mildew.
Worst case, I will give my small fall-delivered roses a chance to grow in a controlled environment before being planted out in the spring. Best case, I may get a few additional crosses out of it!
I appreciate your advice.
Cathy