Pests and diseases: Prevention is the best way to avoid pest and disease problems. Start with disease-resistant varieties, keep plants in healthy condition (well fertilized and well watered), maintain good air circulation, keep foliage dry, and remove any diseased foliage or spent flowers. For Japanese beetle grubs, use beneficial nematodes or Milky Spore (Bacillus popilliae). Rose Rx is effective against scale, spidermites and aphids. For more information, see the Pest and Disease Finder.
The ripened rose hip is then placed on a clean cutting board and cut in half to remove the seeds. Place the seeds in a clean container. Add some diluted bleach to kill off any bacteria and fungus spores. You can make the bleach by mixing drinking water with two teaspoons of household bleach. Stir the seeds well before rinsing them and using bottled water to remove all the bleach. To further clean and disinfect the seeds, put them in the container and add some hydrogen peroxide. The seeds can be soaked for up to 24 hours before rinsing them with clean water to clear all the hydrogen peroxide.
Just as with many other shrubs, roses can be grown from cuttings. It’s not a fast process – it may take a couple of years before your new plant produces flowers. But if you have a favourite rose, it can be fun to try. The cuttings need to be taken fresh from a healthy plant – don’t try to grow a new rose bush from the bunch of cut flowers you have sitting in a vase. And as roses bushes are pruned during winter, this is the most convenient time to take and pot up your rose cuttings.
The rose seeds can be planted right away if you have harvested them as late as November, December or January (in Southern California) or early spring after danger of frosts in your area. Place the rose seeds about one-half inch deep in a very light mixture of 50% sterile potting soil and 50% vermiculite. Some rose hybridizers use Sunshine Mix #4. You can use small pots or shallow trays to plant your seeds, whatever works for the space you have, as long as they have good drainage. Nursery flats work well for this. Lightly dust the rose seeds with RooTone or Captan before covering with soil. And then dust the top of the soil again, which will hopefully help to prevent damp-off (a disease which kills young rose seedlings). Amateur rose hybridizers concerned with toxic chemicals may want to periodically spray the seed tray with diluted peroxide and water instead of the more toxic Captan.
I bought hybrid tea roses last year. Not long after the first blooms, we moved one because it was interfering with the sprinkler system. It looked unhappy at first, but continued to bloom throughout the season. This year, it does not have so much as one leaf, no new foliage whatsoever, however, there is still green inside the stem towards the base of the cane. Is it done for, or is there a chance it will come back in it's second rear?
Next fill your trays or pots with the potting soil. You can opt to use 50% sterile potting soil and 50% vermiculite, or half peat and half perlite. When the potting mix is ready in the trays or pots, this is the time to take off your seeds from the towel. Remember the seeds must not be removed from the plastic bag until they are ready to be planted. You lightly dust them before planting.
When you grow roses from seed, you are essentially developing new varieties of roses. If the rose fruit -- called a hip -- was produced by bee pollination, you don't know what varieties were crossed to get the seeds. Rose breeders hybridize chosen varieties and select for particular traits in resultant seedlings. However, each seedling will be a surprise. Rose seeds have to be collected in the fall, cleaned, and cold-treated before they are planted. Even though the cleaned seeds may look dry, they are not dry inside. If rose seeds are allowed to sit around in the open air and dry up completely, they will not grow.
Allow rose hips to develop by leaving dead flowers on the plant. The flowers are typically pollinated by insects, or pollinate themselves in some varieties, so there is no need to pollinate by hand unless you are breeding specific plants together. Leave the flowers on the rose plant without cutting them. After they wither, small fruits known as rose hips will develop in their place.
Remove the rose hips once ripe. The rose hips will start out small and green, then change color as they grow until they are completely red, orange, brown, or purple. You may pick them at this point, or wait until they are just beginning to dry out and wrinkle. Don't wait until they are fully dry and brown, as the seeds inside may have died by this point.
Once you have had several weeks of below-freezing temperatures, cover the base of the rose with 12 inches of soil or mulch, and then cover the canes with straw, leaves, pine boughs or even foam insulation. Climbing roses can be wrapped right on their supports, or you can lay them on the ground and cover the canes with straw or brush. In severely cold climates, hybrid teas are sometimes partially dug up, laid down onto the soil, and the entire plant is then covered with more soil or mulch.
Water: Roses require more water than most other landscape plantings, especially during the first year as the plant is getting its roots established. The best way to water your roses is with drip irrigation. It concentrates the water at the root zone where it is needed, and keeps the foliage dry to minimize disease problems. A good, thick layer of organic mulch will help conserve moisture, reduce weeds, and encourage healthy root growth. As the mulch breaks down, it will also add organic matter to the soil.
To get the best success, yor rose seed will need a period of stratification (a cold period of about 6-12 weeks). Its a good idea to time this so that it coincides with when they would naturally start to grow in spring – probably around early March, depending on weather conditions. I would look to sowing them in late November/ December and popping them outdoors or if we have a mild winter then stick them in the fridge!
The next step when you grow roses from cuttings is to use a pencil or metal probe push down into the planting site soil to make a hole that is deep enough to plant the cutting up to about 50 percent of its overall length. Place the cutting that has been dipped into the rooting hormone into this hole. Lightly push the soil in around the cutting to finish the planting. Do the same thing for each cutting keeping them at least eight inches apart. Label each row of rose cuttings with the name of the mother rose bush it was taken from.
I too, have tried the cut rose flower method, but haven't yet been successful--perhaps because there are chemical additives that the roses have soaked up, or because there are no nodes (which are the points where new shoots grow out), or because the stems have spent much of their energy producing the flowers...BUT, perhaps if the flowers were immediately cut off and some rooting hormones applied to the bottom cut ends, that may work.
Cover the cutting loosely, pot and all, with a plastic bag or plastic wrap and keep the soil moist. Putting a tall stake into the pot will hold the plastic away from the leaves. If the plastic touches the leaves, they remain wet and can succumb to a fungus disease. Along the same lines, make sure the condensation can escape from the plastic or the stem will rot.