Hybridizers

Hybridizers

By Jim Hole

The rose is one of the most cherished garden plants and enormous efforts are directed toward  the production of new, exciting rose varieties by a multitude of professional plant breeders. But why wait for the professionals to hand new varieties down to you on a silver platter when you can develop them yourself?

From the perspective of most gardeners, plant breeding is an arcane science that is undertaken only by scientists with PhDs who parade around in white lab coats. Nonsense! The development of new plant varieties is within the grasp of anyone with the desire and patience.

The first step to producing new roses is to join your local or national rose society. They often provide plenty of information in their newsletters, and members may share their hybridizing experiences with you. However, to give you an idea of what’s involved in home hybridizing, here’s a simple breakdown of the major considerations.

The basic principles behind creating a new rose variety are really quite simple. Pollen from one rose is transported by hand to the stigma in the flower of another rose plant of a different variety. If pollination is successful, rose hips will swell and the seed contained within will ripen by fall and hopefully contain a gorgeous new variety that you helped create.

Of course, I’ve left out a few little details on the road to successful seed production. There are four essential elements in successful amateur hybridizing: plenty of patience, the right parent varieties, a little extra space both indoors and out to grow roses and seedlings, and a desire to learn and experiment.

Patience is mandatory when attempting to breed your own rose varieties; for one thing, you will have to wait an entire season to get seed, and then wait months for that seed to germinate, and still more months for the seed to grow into a mature, blooming plant. Even then, the road to developing a new, wonderful rose is inevitably strewn with many truly unspectacular roses. It may take many years to grow a rose that you would be proud to show off.

That’s why it’s so important to choose your parent varieties carefully; when it takes what seems like an eternity to achieve good results, you want to start by choosing parents that will give you the best odds at a superior offspring.

When selecting parent varieties, the first factor to consider is that the seed of some varieties simply will not mature in time in some regions with cooler climates. Keep in mind that parent plants that are late to set hips are usually bad candidates for short season areas.

Rose hybridizing societies have extensive lists of roses that are good choices for crossing. But don’t be afraid to experiment; that, after all, is the point of your endeavors.

Step by Step

The key to successful pollination, beyond choosing species and varieties that will mature before winter arrives, is to focus on the proper transfer of pollen to stigma, at the best time of the season, and the best stage of flower maturity.

Pollen is the yellow powder contained in the tiny capsules surrounding the central stigma of the flower. The pollen capsules should be cut from flowers of the rose that you select as one parent of your new rose variety and stored indoors for a day or two until the capsules split, releasing the pollen.

On the rose plant that you choose as the other parent, it’s critical that you select flowers that will open only on the day of cross- pollination. In the early morning, remove the petals on the flowers of this plant to get to the stamens, which carry pollen. If these stamens are left in place, they will self-pollinate the flower, ruining your attempt to cross-pollinate, so they must be removed. Do so, but be careful so as to avoid damaging the pistil, which supports the stigmas that will receive the pollen from the other parent variety.

An artist’s brush is a good tool for dabbing in the pollen and spreading it onto the stigma. The stigma is usually most receptive in the early afternoon, so it’s best to do the work then, when your odds of a successful cross will be that much greater.

Keeping records is critical. Tag the parent plants with durable metal tags, and keep a journal of all the crosses. Tagging the hips, once they mature, is also critical to chart your course and have accurate details of lineage.

October is the typical harvest time for hips. Bring them indoors and store in a cool, dry, dark place. After about a month, the hips can be split, the seeds extracted and then grown in a seedling mixture over the winter.

All of the tools (grow lights, seedling tray, growing medium, fertilizer, etc.) and rules used for the successful germination of any seed will also be needed for rose seed. In brief: use a high quality seedling mix, keep it moist and check your progress regularly. Temperatures should be around 12–15° C, with lots of light.

Remember that seed germination is slow and may take a couple of months. Also, don’t be surprised if very few seeds germinate. Roses often have very complex lineage, and species can vary a great deal with respect to the quantity of their chromosomes. The result is a fair bit of sterile seed, depending on the parents chosen.

Come spring, you should have a number of seedlings ready for transplanting into the garden. Remember to harden them off by putting your trays out on the porch during the daytime and bringing them in at night for a few days. Then, transplant the seedlings into your rose garden, preferably in a sheltered location with full sun and rich, well drained soil (the resulting hybrid may or may not be all that hardy in cold winter climates. Winter protection is essential in these regions). With any luck, before season’s end, you’ll enjoy the fruits—or rather, the blooms—of your labours. If you’re one of the fortunate few to come up with something truly spectacular, let your rose hybridizing society know, and they’ll put you on the road to registering the new variety. You may even get to name it.

Be patient, try lots of crosses and don’t be disappointed when seeds don’t grow. That’s not a failure; it’s just a footnote for you journal.