New plants from seeds
Rose breeders wanting to produce totally new rose varieties pollinate one rose variety with another and grow hybrid plants from the resulting seeds. The activity is known as hybridizing and can be an engaging pastime for the home rose grower as well. The mechanics of hybridizing are so simple that insects, the wind, and the roses themselves do it with the greatest of ease and frequency. The hips that decorate many old roses in autumn or that you remove from your hybrid teas are the result of such natural forces at work. At first you may want to plant seeds from hips that form naturally. Until the mid-19th century most new roses came from such unplanned crosses. Doing this will give you the experience of harvesting, planting, and raising new plants with the minimum of disappointment should any fatalities occur. The blooms on these seedlings are likely to spur you on to planning and making definite crosses-either because they are so fascinating or because they are so nondescript that you feel a little guidance is needed!
When to hybridize In all regions where you can count on frosts in October, do all your hybridizing with the first crop of bloom in spring. Hips require about 4 months to form, mature, and ripen, and you want this process completed by the time cold weather arrives.
When mature hips turn orange, yellow, or brown, they are ready for picking. Usually this is in early autumn. In regions where the growing season is short some rose hybridizers cover the full-sized hips in midsummer with aluminum foil. This hastens ripening so that all hips will be ready by the end of the season.
An after-ripening period of low (but not freezing) temperatures combined with moisture is claimed by some hybridizers to improve the percentage of germination. As you pick the ripe hips, put them in boxes or plastic bags where you can cover them with damp sand, vermiculite, or peat moss. Then, put these in the vegetable crisper of your refrigerator. You can leave the after-ripening hips outdoors if you prefer, but see to it that they are safe from mice and squirrels.
Any time from the beginning of December to mid-January, remove the hips from their after-ripening quarters (they'll be black and partly decomposed by then) and shell out the seeds. These will be of odd sizes and shapes, but a convenient indicator of which are good and which aren't is the water test: plant those that sink in water; discard seeds that float.
Planting the seeds Growers of rose seedlings have many favorite ways to plant and germinate the seeds, but they break down to two basic methods: either you plant the seeds close together in fairly shallow containers and transplant seedlings soon after they come up, or you sow them in flats or boxes where they will remain until they flower. The first method probably is more popular because, initially, it uses less space and less potting soil. But it does require more labor because you have to transplant. If you plant seeds where they are to bloom, use a flat or box at least 3 inches deep; sow the seeds an inch apart in rows about 2 inches apart. In either case, cover seeds with 3/8 to 1/2 inch of the potting soil.
Seeds often will start to germinate within 6 weeks of planting and will continue for about 2 months. The first two leaves to appear are oval shaped and not at all rose-like; it is the second set that proves they are roses. As soon as this second set is out, you can transplant the seedlings. As an improvised trowel to lift the tiny plants, use something like a nail file, knife, or ice cream stick; try to keep some soil around the seedling roots during the operation. If it is a cross you particularly value, you may want to keep the seed bed intact for another year. Some seeds which fail to germinate the first spring may grow the next year.
