Welcome to the February 2004 edition of my web site! The roses I write about are the Old Garden Roses and select shrub and miniature roses of the 20th century. For tips on rose culture, pruning, propagation and history, see the "Site Resources Guide" box in the navigation panel at left. To return to this page, click on the "thorn icon" in the margin at left. Articles from the previous months are archived and can be viewed by clicking on the listings in the left margin. Oh, and please don't write to me for a catalog or pricelist.....this is an information site only, not a commercial nursery. If you wish to buy roses, see my sponsor, The Uncommon Rose.
Approach to Pollination of Roses, Harvest of Seed and the Production
This article resulted from a request from the editor of the Rose Hybridizers Association newsletter to contribute to a series of articles on breeding. The Rose Hybridizers Association is a dedicated group of amateur and professional rose breeders that shares a great deal of valuable information via its web site and in its quarterly newsletter. I encourage all interested hybridizers to join the group; its a mere $10 a year!
I believe that parent selection has a great deal to do with how good your germination rates are. I have tried several varieties over the years and no matter what I do, germination was poor to nonexistent. I abandon those varieties quickly and move on to roses that are more willing to reproduce. (I still experiment with unknowns to determine fertility) Keep in mind that some plants may be poor seed producers but have highly fertile pollen! See my list of cultivars I have used and my assessment of their willingness to produce seed/pollen. (At the end of the article)
Any seasoned hybridizer will tell you that it is very important to work with plants that will speed you along in your work as quickly as possible. IE: you must produce as many seedlings each year as you can cope with. And so, I choose willing parents. The tray of seedlings you see above is a cross using 'Sheri Anne', a most willing seed parent. (pollen parent was 'Crepuscule') While it does breed a lot of miniatures (some very interesting ones, I might add!) it will also breed a percentage of shrubs and climbers when bred with full sized roses. This applies to most of the Miniatures.
I use a number of named commercial varieties for breeding, both Miniature, Climber, and Shrub, and some proprietary seedlings because they are willing parents whose seed germinates easily and in large numbers. A short list would include: 'Abraham Darby', 'Rise 'N' Shine', 'Penny Ante', 'Scarlet Moss', 'Cardinal Hume', 'Sequoia Ruby', 'Sequoia Gold', 'Orangeade', 'Tuscany Superb', ''Fairy Moss', 'Dresden Doll', 'STW-1', 'Mary Rose', 'Golden Angel', 'Joycie', 'Lilian Austin', 'Little Darling', and a number of un-named breeding plants given to me by other hybridizers or of my own breeding.
Treatment of the Seed Parents
I'm not convinced that your seed parents need a lot of special handling
other than giving them reasonable good care and keeping them disease
Breeding plants should be pruned sparingly, if at all. As roses build up size and wood, they appear to become more fertile and more willing to produce seed. I have been advised by others to limit how much I prune my seed plants. I now prune the tips of the canes in late Winter, reducing the size of the plants by no more than 1/4 at most. Many hybridizers will also tell you not to pamper breeding plants too much. Don't feed them as you would feed plants that you grow for garden performance. Starve them a little. My plants get a few feedings through the Summer, but only a few. This applies more to the potted plants in the greenhouse; the outdoor plants often get one feeding early in the year and no more after that. Some breeders (Ralph Moore) apply a slow release dressing in early Spring and no other feeding is done the rest of the year. He believes a hungry plant is more likely to want to set viable seed as a survival response to starvation.
Some people say the same thing about restricting water, but I have my plants on automatic watering, and so they are never stressed for water. Still, they set seed easily and it usually germinates very well, so I don't feel motivated to change my approach at this time.
Preparing the parent, collecting pollen
For me, pollination is a pretty standard operation. I don't do anything
special or unique, but I am meticulous with the labeling of pollen and
the pollinated blooms.
method for dealing with pollen is dependent on my storage equipment.
My favorite pollen storage is a set of Watchmaker's cases which are
small metal canisters that have a glass-topped removable lid. These
come in sets of 20 or so, and you can label each container with a permanent
marker on the glass lid. Lee Valley Tools sells these watchmaker's cases
Some hybridizers will prepare the female bloom a day in advance, so that the stigma is receptive to the pollen. (It gets sticky and sugary) I have found that in practice, it makes little or no difference how far in advance you prepare a bloom for pollination. It is my standard practice to emasculate the blooms only minutes before pollination. No matter when I make the pollination, the vast majority of them take readily and result in hip formation. I have rarely felt it necessary to take special measures to obtain fertilization, but then I tend to avoid working with cultivars that are reluctant to breed. (I don't want to end up working myself into a genetic corner with varieties that will be reluctant to continue a line of breeding, if possible. There are always exceptions where this is necessary or desirable, of course.)
have long ago given up on using brushes or (worse yet) Q-tips to deliver
pollen to the stigma. Brushes require cleaning between pollen varieties,
Q-tips get caught on the stigma and waste a lot of pollen that gets
trapped in the cotton fibers. I find that using a clean fingertip is
fast, efficient and accurate. All you need to do when you change to
a different pollen is lick your fingertip and wipe it dry on a clean
shirt. Do whatever works for you, but this is the fastest, most basic
approach I have tried and requires no special equipment.
I do not cover the pollinated bloom with anything. My early experiences of covering the bloom with aluminum foil resulted in a lot of rotted hips that never got a chance to form. Several other hybridizers I know no longer cover the pollinated bloom, as they feel that if you have emasculated the bloom properly and placed sufficient pollen on the flower, then the occasional bee isn't going to have much chance of contaminating your work. “My pollen got their first” is my way of thinking about it, and my work indicates that my crosses remain true as far as the results are concerned. If it makes you feel better to cover your pollinated blooms, go for it. The rest is up to the plant, at least until harvest time.
Harvest and Aftertreatment
It is at this time that my crosses are cataloged and given identification numbers. I use the same coding system that many others hybridizers use: a three number code. For example, one seedling I have selected this year is numbered 42-02-02. The first number indicates that it was cross number 42 and tells me what the parents were. (This data is kept in a spreadsheet file) The second number tells me that the cross was made in 2002. The third number is the number given to the individual plant, in this case, seedling number 02 from the lot selected. Naturally, only the first two numbers are given to the seed batches at the time of harvest and collation.
My harvest, storage and stratification procedure is pretty standard, I believe. I harvest seed when hips show color. Some hips of some varieties are harvested the moment they show any color at all. Certain cultivars don't always color by the time they are ready for harvest, Teas in particular, so I tend to collect them all regardless of color. I am beginning to believe that seeds harvested a bit early may germinate more readily, especially with hard to germinate cultivars.
Seed hips are bagged (with seeds intact), labeled and stuffed in the fridge until late December or early January, when I decide to start extracting the seeds from the hips. I used to remove the seeds immediately after harvest, but in the interest of experimentation (and laziness) I now leave it until much later. Peter Beales describes a similar approach in the chapter on propagation in his book Classic Roses, in which he suggests storing the hips in damp sand until February, when the hips are likely decomposed and easy to clean the seeds out of. Decomposition of the hips doesn't affect germinability. If anything I believe it enhances germination.
Seeds are removed from the hips manually, with a blunt-ended pocket knife. Sure, its very time-consuming, but I prefer to work this way. Other breeders do the seed extraction with a blender and a lot of water, but my attempts at this approach have been less than satisfactory. For one, I don't like the fact that a percentage of the seeds end up broken and destroyed, and I also get a lot of sinewy material that doesn't break down in the blending process. This material is difficult to separate from the seeds, and so I quit using the blender. I'd rather spend a week cleaning the seeds from the hips by hand rather than risk damaging them. If you can make the blender method work for you, great, but I'll stick to doing it manually.
Seeds are then put back in Ziploc bags with a damp paper towel and returned to the fridge. They receive no treatment to prevent mold growth at any point during refrigeration. I think mold can help break down the seed coat, and is a natural part of the destruction of the achene and its inhibitors. Passing through the digestive tract of an animal or bird serves a similar purpose: breaking down the outer achene and removal of germination inhibiting chemicals. If you find mold is damaging your seeds, by all means treat to prevent it. Some people use Captan fungicide, but since it is considered a cancer risk, you shouldn't use it in the same refrigerator you keep food in! Curiously, Ralph Moore uses Comet Cleanser in with his seeds to prevent mold. Since this has apparently been his habit for years, I trust it doesn't harm the seeds. Youmay want to try a solution of Hydrogen Peroxide and water instead. (Henry Kuska can elaborate on exact dilutions for this)
Seeds are not allowed to germinate in the fridge, as a general rule. Germinating seeds are too easily damaged if you have to move them from the paper towels to pots, and so I try to always sow all my seeds before much germination begins. Some people have success germinating their seeds in the fridge and then potting them on, but I found that many seedlings were damaged and died during handling using this approach. I find that seedlings allowed to germinate in a cool greenhouse under early Spring light conditions are much sturdier and will tolerate rough handling much better than seeds that germinate in darkness in the fridge. Another reason to sow the seeds before they start germinating in earnest is so that any molds that are present won't damage the tender seedlings.
FYI, my seeds receive a total of 12 weeks (or more) stratification in the fridge, cumulatively. (Total for pre and post removal from the hips)
Sowing the Seeds
Usually, I sow the seeds in the third or fourth week of February. Seed trays (purchased from a wholesale supplier: Steuber Distributing, Snohomish, WA) are about 3 inches deep with hundreds of perforations on the bottoms to allow perfect drainage. They are sturdy and can be used for years without deterioration. (Bleach sterilize trays each year before re-use.) I use various seed mixes, depending on whats available from my local garden center. I find little difference between the commercial soil-less potting mixes as far as how the mix affects germination. I simply buy whats available. Last year it was Gardener and Bloome potting mix, which contained a lot of semi-composted bark fines. It provided excellent germination, but was poor for potting on later, as it appeared to have inferior nutrient content. (Un-composted bark fines can steal Nitrogen from the mix, even when applying fertilizer)
Two inches of mix is placed in each tray, the seeds are sown in rows (or broadcast evenly over the whole tray if there is a lot of a cross) and covered with about 1/4 inch of mix. They are then watered and placed in an unheated greenhouse where they are exposed to temps that fluctuate between 32F and 55F. Whenever the trays need watering, I use dilute Hydrogen Peroxide as a damping-off preventative. It is very important to use some preventative or fungus can destroy many seedlings almost overnight. I believe the dilution rate I use is one part H2O2 to 19 parts water. (Henry Kuska's idea, thanks Henry) It is a non-toxic alternative to using fungicides like Benomyl.
Alternatively you could try what Ralph Moore does at Sequoia Nursery, which is broadcast the seed on the soil surface and then cover it with ¼ inch of fine perlite. This layer of mix seems to prevent Damping-off by some mechanical means.
After germination, seedlings are pricked out and potted up individually into 3 X 3 inch pots. This is done at the point when they have at least one true leaf forming, or later. I try to pot up at least 36 seedlings of any cross so that I can label one or two pots in a tray, indicating the entire tray of 36 is one cross. Partial trays are sometimes have a label in every pot to avoid confusion. The seed mix of choice for potting on is Black Gold Potting Mix, which gives excellent seedling growth. As seedlings begin to show flower buds I start to fertilize them with ¼ strength soluble fertilizer. (Usually something of a 1-1-1 ratio) Fertilizer is applied about once every 10 to 14 days.
The seedling house is sprayed to prevent Mildew, at least until the seedlings start to bloom. Experience has shown me that many mildew prone seedlings later develop resistance as adults or when they are placed outdoors where they get better air circulation.
Culling begins at first flowering with the removal of poorly colored, badly shaped flowers, or weak growers. I will often save a good looking plant for a second year, regardless of the fact that it may not have bloomed the first season. Some crosses (Bracteata hybrids) typically produce seedlings that will not bloom the first year, but may become remontant in the second or third years. It is wise to retain some of the best looking individuals for a second year, as some of them turn out to be very worthwhile. Remember, the plant itself is ultimately more important than the bloom alone.