The oldest method of propagating roses is from their seeds. This method of propagating roses is very easy and also does not require much equipment. You just require pots/ containers, sowing flats and, if possible, fluorescent or greenhouse lights. However, if you don’t have a greenhouse or access to one, you can also germinate the rose seeds on any windowsill, in a basement under proper lights or even outdoors in pots or the ground.
It generally takes about a year from making a cross to the rose seedling bearing the first flowers of a new variety. In fact, most growers find this long wait worthwhile, because the delight of seeing the new as well as the extraordinary bloom is extremely pleasing.
If you intend to grow roses from their seeds, you should first harvest the seeds. In order to harvest the seeds, you need to cut the rosehips when they are mature, rinse them and use a sharp knife to cut them into the half. Once you have done this, you can easily remove the white seeds, which are somewhat pointed, and roughly 1/ 8 of an inch long. The shape of these seeds may vary from round to oval. One rose hip may enclose anything between just one to 50 tiny seeds. After you remove the seeds, use a kitchen strainer to wash them meticulously.
While you can sow the rose seeds immediately after harvesting them, they generally germinate better when they are placed in a plastic bag or airtight jar and stored in a refrigerator for some time. When you place the seeds in the plastic bag or sealed container, ensure that you keep them in layers of damp sphagnum peat moss, moist tissue or moist paper towels for anything between six and eight weeks. This will help the seeds to germinate successfully. For the uninitiated, this process is called stratification and it helps to induce the cold conditions that prevail naturally during winter months and stimulate the seeds to sprout better and earlier.
Once the cold treatment is over, remove the seeds from the paper or moist sphagnum peat moss using tweezers. Before you sow the seeds, you may possibly want to examine if they are viable or will germinate properly. For testing the viability of the rose seeds, you should put them in water in a container. The seeds that do not possess the ability to germinate will float in the water. Discard these seeds and sow the ones that have sunk to the bottom of the water container.
It has been often found that rose seedlings are extremely susceptible to a disease called damping off. One or several fungi are responsible for this ailment. These fungi are present in nearly all garden soils. The seedlings that are affected by damping off usually wilt and collapse all of a sudden after they germinate. As of now, damping off does not have any cure. Hence, prevention is the best remedy for this disease. Therefore, ensure that you always use a sowing mixture that is sterilized as well as soil-less.
For best results, take a wide, shallow container with roughly 4 inches of growing medium and plant the rose seeds in a manner that they remain 1/4 inches buried under the soil-less medium. You should know that these seeds sprout best when sown in a greenhouse. However, if you do not own a greenhouse or have access to one, you can wrap the seed flats using glass or transparent plastic sheets. Alternatively, you can also put the seed flat inside a transparent plastic bag so that the growing medium remains moist and there is high humidity till the germination of the seeds.
Remove the plastic sheet or glass for some time if you see condensation forming under them with a view to slightly dry the growing medium and check diseases from spreading. It has been found that rose seeds germinate best when they are kept at a temperature ranging between 50°F and 55°F. However, they also germinate well at higher temperatures like 60°F. Keep the seed flats in bright light for as long as you want to, but never in full sun. Alternatively, you may also place the flats about 6 inches to 10 inches under fluorescent lights, which should always remain on till the seeds sprout.
It may take anything between just three weeks to as long as four months for the seeds to germinate. Sometimes, it may take even longer. When the cotyledons (short shoots with two seed leaves on either side) appear, get rid of the plastic bag, plastic sheet or glass and keep the containers under full sun for as many hours possible. Alternatively, you can also place the containers under fluorescent lights.
Inspect the new sprouts every day after the germination to check if the medium has become dry and if you need to water it. Ideally, you should use a spray or mist to water the medium. Alternatively, you can place the container in a water tray to allow the medium to absorb the required moisture from below. When you find that all the seedlings are growing healthily, make sure that their growth remains steady. You can accomplish this by adding a soluble fertilizer, for instance, 15-30-15 or 20-20-20, to the irrigation water at one-fourth of the suggested strength once every week.
You should know that it is time to transplant the seedlings into separate pots when you see that they have grown three sets of compound leaves. While transplanting the seedlings, you need to dampen the medium in the container where they are already growing. Now, take peat or plastic pots measuring two inches and fill them with the wet growing medium. Next, make a hole in the middle of the pot to the depth of the seedlings’ roots. Ideally, the hole should be made with a tool called dibble, but you can also use a pencil for the purpose. Lift the tiny seedlings gently using a spoon handle or wooden plant label. While lifting the seedlings, ensure that you do not disturb their roots.
Hold each seedling by its leaves and lower it into the hole you made in the medium. Subsequently, press the medium around the root gently. Having done so, keep providing the seedling with water, light and fertilizer. While transplanting the seedlings, be cautious not to handle them by their stems – the stems are very delicate and may break.
Instead of planting rose seeds in large containers, you can sow them into individual 2-inch pots directly after filling them with an appropriate growing medium. This will be helpful as it will do away with the transplanting process and also avoid handling the delicate seedlings. Moreover, sowing the seeds directly into pots generally also yields relatively larger plants just after one year of their existence. When the young rose plant has grown up to a height of four inches, transfer the entire root ball along with soil to a larger pot (4-inch) and fill up the additional space with potting medium.
You can also directly sow the rose seeds outdoors in the garden. Before sowing the seeds, prepare the soil well. You can do this either at the end of fall or at the beginning of spring so that they germinate between the middle of spring to spring end. You should know that the cold weather outside will not harm the rose seeds. Precisely speaking, the cold climatic condition will stimulate the seeds to germinate. If you are sowing the seeds in the garden directly you need to plant them half-inch deep into the soil and at a distance of one inch from each other. The seeds should be sown in rows that are spaced out about 2 1/2 inches.
After sowing the seeds, ensure that their bed does not become dry. You should continue watering and begin providing light concentrations of soluble fertilizers to the seedlings after the appearance of the cotyledons. For instance, you may provide the young plants with fertilizers like 15-30-15 or 20-20-20 at 1/4 concentration of what is recommended on the product label once every week till the plants bear their first flowers.
Usually, the first rose blooms appear when the seedlings or young plants have grown to a height of 4 inches to 5 inches, which may take anything between six weeks to eight weeks from the date of germination. At the same time, you should not be disheartened if you do not find the initial blooms to be exciting because usually, the first flowers do not represent what the mature blooms will be looking like. You can only take a decision to keep or discard a plant after it has bloomed many times.
For instance, if you find that a seedling has some potential you can shift it to a permanent location in your garden and allow it to continue growing on its own roots or you may even graft the plant by growing it on a further robust under the stock. So how do you assess if a plant has some promise or not? To understand this, you should see if the flower of the plant has an exquisite color or has a good form.
It is advisable that if a plant is robust and producing desired flowers, you should allow it to continue growing on its own roots. There are two main reasons for this. Firstly, roses growing on their own roots are never troubled by suckers, which develop from the understock and rob the plant of its energy. Secondly, the rose varieties that are robust and resilient will usually grow faster and also produce blooms that are superior compared to the grafted plants. Moreover, roses growing on their own roots are also able to overwinter much better compared to plants growing on understock that is equally robust.
Then again, tender roses do not grow healthily on their own roots. They will grow much better when they are budded. However, it is not possible to forecast if a recently hybridized rose variety will turn out to be vigorous or resilient. Therefore, if you find that it is not growing well on its own roots, you should try budding the plant and watch out for the results.