The Fine Art of Breeding Roses
A Step-By-Step Hybridizing Tutorial
By Kathy DeRoo
As we come into April's first bloom cycle we find ourselves at the beginning of rose hybridizing season. Hybridizing, the fine art of breeding roses, is a facet of rose growing that is a hobby all by itself, beginning with cross-pollination and ending with any number of new seedlings.
If your goal is an AARS (All-America Rose Selection) award, you've got about 8-10 years from pollination to commercial introduction, and a gauntlet in between. But if you just love playing with roses and the idea of creating your own individual rose varieties appeals to you, each step along the way is fun and exciting!
There are as many methods as there are rose hybridizers, so I will try to boil it down to the easiest techniques for the beginner.
First you must gather together your "kit." You will need:
- spiral notebook, 9-1/2" x 6", in which to record crosses and observations.
- ballpoint pen (the ink won't run)
- self-adhesive labels - I use 3-7/16" x 9/16" file folder labels, cut in half lengthwise
- small scissors, such as cuticle scissors
- film canisters or small cups for collecting rose pollen
I would also recommend the booklet, Rose Hybridizing for Beginners from the Rose Hybridizers Association. I refer to it often, throughout the various stages of rose breeding. It is available for $5.00 (payable to RHA) from Larry D. Peterson, RHA Secretary/Treasurer, 3245 Wheaton Road, Horseheads, NY 14845.
The pens, tweezers, swabs, and scissors are kept together in a small cup. Put all the items together in a box (a plastic Rubbermaid box works well) so you can carry it back and forth in the garden as you need it.
Now you must survey your garden and decide which rose plants to use for parents. What do you like? Hybrid Teas? Stripes? Fragrance? Personally, I have a soft spot for miniature roses, so I use one in almost every cross - a miniature crossed with almost anything produces a high percentage of minis.
Some roses make better parents than others. Here are a few that have been "proven:"
Peace Gold Medal
White MasterpieceSilverado
Olympiad Pristine
Paradise First Prize
Party Girl Rise 'n' Shine
Fairhope Black Jade
Sometimes the easiest way to choose is to see what's blooming, and what two rose plants seem to complement each other in some way. That's how I came up with a cross of Tennessee (Mini) x Color Magic (HT) last year - it produced more seeds than any other single cross I made that season.
Working in the early morning or early evening, I begin by collecting rose pollen first. The easiest method I have found is to locate a bloom of your pollen parent rose, say First Prize, that is almost, but not quite fully open. With clippers, cut it off the bush with about a 2" stem. Pull off all the rose petals and sepals (those 5 green flaps under the petals) to reveal the yellow stamens and pollen sacs. Gently place it upside down in a film canister or cup labelled with the variety name on a piece of masking tape, and leave it at room temperature to dry. In 12 to 24 hours the pollen will be released from the sacs, appearing as a golden-yellow dust. It will remain viable for 3-4 days at room temperature, or up to 4 weeks in the refrigerator. I keep the pollen cups in the kit box so I can tote 'em as I go from rose to rose (but be careful not to spill!).
Now go to your seed-parent plant - let's try the hybrid tea rose White Masterpiece - and locate a bloom in a similar stage of maturity. Do not cut it; don't even grasp it by the peduncle (the stem below the bloom). Hold it by a sepal or the base of the bloom and gently remove all the petals, using tweezers if necessary. Do not remove the sepals, as they are believed to protect the developing hip from the harsh rays of the sun. With your small scissors, cut away the rose stamens, going in a circle around the stigmas, which are in the center. Try not to injure the styles and be sure to remove all pollen sacs (some filament may remain). As you work, you will discover how distinct each feature of the bloom is, and how easy it is to locate and remove the correct parts.
It will take 12 to 24 hours for the stigmas to exude a clear sticky fluid (some varieties are more obvious than others), signalling readiness for pollination. You may want to put a "hat" on your prepared female, but it's really not necessary (pollen-carrying bees are only attracted to the petals). I made rectangular covers out of plain white paper, folded and taped, and I kept them on the blooms for 3 or 4 days. I found that they helped me locate the blooms that were awaiting pollination, and I believe they offered greater protection from the hot summer sun. I had a higher success rate with the hats than without them so I will use them again this year.
Keep notes in your notebook of your intended crosses, what pollen you've collected, and what new crosses will be made tomorrow.
On the following day when you return to the prepared White Masterpiece bloom with your kit, take out the First Prize pollen cup, carefully pull the stem out of the cup so as not to lose any fresh rose pollen, and using the stem as a handle, apply pollen to the stigmas. I like to apply most of the pollen right away, reserving a little bit for the next day (if necessary, use a cotton swab to collect remaining pollen from the cup, but never use the same swab for more than one variety). I like to pollinate 4 times - twice a day for 2 days - but you can get results by making crosses once a day, up to 3 days in a row.
Write the name of the pollen parent (First Prize) and the date on the label and wrap it around the peduncle. In your notebook, log the cross you've just made, including time of day if you work twice a day. This entry would read: "4/15 White Masterpiece x First Prize, a.m." (the seed parent is always listed first). When I return to repeat-pollinate this particular bloom I will simply add "p.m." or "4/16" to the entry. You should also begin a numbering system on a separate page in your book, such as "95-1 White Masterpiece x First Prize" - year first, cross number second - so that all similar crosses will bear the same number. Use indelible ink to mark the cross number on the label you've placed on the seed parent.
After pollinating whatever you've prepared, you must go in search of more rose pollen for the next day, and then prepare the mother blooms again. And if you decide to try something different, you ought to write it down on a "To Do" page in that notebook.
Here in California, rose breeding season usually lasts from April until the end of July. The rose hips need 4 months to fully ripen before the weather gets too cold.
As you watch your rose hips swell and ripen, you will suffer some losses. It's not unusual to lose 50% or more of the crosses that just didn't "take." Be careful not to overfeed your mother plants or you could lose even more hips.
Most rose hips turn orange-red when nearly ripe but some, like Gold Medal, stay a dull green color. When the peduncle begins to dry out and turn brown you can be sure that the hip is ready for harvesting.
As you collect ripened rose hips, keep them in a plastic zipper bag marked with the cross number in indelible ink and placed in the refrigerator. When you have several hips collected (and before mold sets in) you can begin shelling out the seeds.
Working on a cutting board, cut into the rose hip with a sharp knife. Don't worry about injuring the rose seeds inside - they're hard as rocks. Any rose seeds you manage to slice would not have been viable anyway. Pick the seeds out of the shell, cleaning all pulp off with your knife or a scrubber sponge. When I have lots of seeds of the same cross, I throw them into a blender with a cup of water and run it for about 10 seconds on medium speed - it really cleans them up! Pour the seeds out into a strainer and dunk them in a solution of 1/2 teaspoon Captan (50%) to a pint of water, to prevent mold.
Some rose hybridizers perform the "float test" at this point - any rose seeds that float are considered non-viable and are discarded - but when you only have a few seeds to begin with, and 10% of floaters do sprout, you might as well save them.
With gloved hands, dip a half sheet of paper towel into the Captan solution, wring it out, and wrap your rose seeds in it. Put them back in the baggie and store in the coldest part (top or back) of your refrigerator. Joe Winchel, hybridizer of many top-notch Hybrid Teas, discovered that by allowing the seeds to lightly freeze at about 30 degrees (even just overnight), he got a much better rate of germination (do not try this in the freezer).
For best results in Southern California, plant the rose seeds during December. You can plant them later but you won't get near as much growth the first year.
I use Fison's Special Mix #3, which is formulated for maximum seed germination, as a growing medium in flats or seed trays. If you can't get down to Orange County Farm Supply to get the Fison's you can use a 50/50 mixture of Supersoil and vermiculite.
Using flats like those that groundcovers come in, you may need to cut a piece of fiberglass screening material (available at Home Depot) to fit the tray, so your soil doesn't fall through the bottom. Fill the flat with moistened soil, patting it in place. With a trowel, carve 8 parallel grooves 1/2" deep, side to side, about 11/2" to 2" apart. Place a bit of RooTone in a film canister and drop the seeds of one of your crosses into the powder. (This is another Joe Winchel trick, which will produce better plant growth in the first year of life.) You can use your tweezers to stir the rose seeds in the powder, then place them in the rows about 1" apart. Spacing them this way makes it much easier to later remove a seedling without disturbing the young roots of its neighbors.
Set the rose seeds deep enough in the grooves to cover them with 1/2" (for Minis) to 3/4" potting soil. Write the cross numbers on plastic plant labels with indelible ink and set them at the end of the corresponding rows (if the entire flat is the same cross you only need one label). When you get a flat planted, water it in a bit (careful that watering doesn't push the seeds into the next row), then spray with the Captan solution using a spray bottle. You will need to spray weekly to prevent damping-off, a fungus which kills seedlings if allowed to attack.
The seed flats should be placed in a protected location (don't let the cat get near them!). Keep them watered but let the surface get slightly dry between waterings. They don't need sunshine until the first seedlings pop up, in 4 to 6 weeks. Germination may continue for a couple of months. On average, only about 25% of your rose seeds will actually sprout. When they show their second set of leaves, which look more like true rose leaves, they may be carefully transplanted into 2" pots with your regular potting soil. The roots are small and delicate at this stage, but if you wait too long you'll have several plants' roots co-mingling and the surgery could prove fatal. Be sure to label each 2" pot with the cross number, and you can add a number for the individual plant, such as 95-1-3, for the third plant of your first cross (White Masterpiece x First Prize) of 1995.
This is a good time to set up a rose seedling notebook. I use dividers labelled with 3 cross numbers for each section, then set up a page for each seedling, with its number at the top of the sheet. Try to keep dated notes on plant habit and bloom details.
So, if you got the seeds planted in December, you should start seeing sprouts in January and blooms by April! This is the most exciting part of the whole process. You just don't know what you're going to get until the first bud opens to reveal its color and number of petals. Probably half of your seedlings will have single-petalled blooms, which are usually not considered "keepers" unless you get an unusual color. Those that are double often improve with age and from budding onto rootstock.
If you come up with something special, bring it to a rose society meeting for evaluation by several rosarians. They can lead you to one or more commercial rose growers who will decide whether your rose is worth testing for commercial introduction or even if it should be entered in the AARS Trials. After a couple of years in the Trial Grounds you will know whether you earned that AARS Award that is so highly prized!
P.S. In 1978, William Warriner of Jackson & Perkins introduced an offspring of White Masterpiece x First Prize: the Hybrid Tea, Pristine.
© Copyright Kathy DeRoo. All rights reserved.
This article is an ARS Award of Merit Winner, originally published in "Rose Ecstasy," bulletin of Santa Clarita Valley Rose Society, Kitty Belendez, Editor.
Photos © Copyright by Kitty Belendez
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