Propagation denotes developing new plants and, like in any other field, it is considered to be a wonderful pleasure in the world of horticulture. In fact, propagation is one of the basics of horticulture. Irrespective of whether one is growing new plants from their seeds or by other techniques like budding, cutting or grafting, the end result is developing new plants. Over several centuries, propagators across the globe have gone through infinite trials and errors to find the simplest ways to generate numerous new plants that attract the interest of gardeners. Every method has its individual advantages as well as downsides. While some of these techniques are perfect for a number of rose varieties, others are not suitable.
Among the various methods of propagations used to grow new roses, division is the least popular. This is primarily because you cannot reproduce the budded rose varieties using this method. On the other hand, roses growing on their own roots can be successfully propagated through the division method. In order to propagate roses using this method, you need to divide a rose into half lengthwise - cutting the plant to make two plants. You can use this method successfully even to propagate new roses from old, slender and overgrown plants. If you are using this method, you need to divide the roses either during the beginning of spring or at the end of fall - the periods when the plants are usually in their dormant stage. If you are living in a place where the climatic conditions are warm, you can also divide the roses in winter.
Dividing a rose bush is not that difficult as it may seem to be. First, water the rose bush thoroughly and scrutinize it closely. Start digging the area around the rose bush with the objective to divide the plant into two lengthwise ensuring that both halves contain equal number of shoots and roots. Use a pruning saw or a sharp knife to divide the plant into half by cutting down from its crown. Subsequently, brush the exposed part of both halves with orange shellac or tree wound paint. Once the sealant has dried, replant both the divisions immediately.
Propagators seldom use the layering method to grow roses. However, layering may be a very practical method of propagating roses, subject to the cultivar. However, you cannot use this method to propagate robust, erectly growing rose varieties, as these types of roses will not bend to the ground. Nevertheless, layering can be used to propagate the rose varieties that are suppler and old-fashioned, ramblers and climbers.
To generate a new plant using the layering method, just bend a one-year old shoot making it touch the ground. Ensure that the contact point with the ground is in a shallow trench and the tip of the shoot remains at least 12 inches (30 cm) away from the point. Next, tie the shoot with a wire or similar object to keep the shoot grounded at that point. Make a wound on the part of the shoot's bark where it is in contact with the ground and cover it with some soil to encourage rooting. This method can be adopted during any season, but the rooting generally takes place faster when layering is done in spring, just prior to the start of the plant's seasonal growth.
After the new roots have emerged and established them somewhat, the tip of the shoot above the ground will start new growth. When this occurs, you may simply cut off the shoot from the parent plant. You can plant the new rose in its permanent position when it is in its dormant season.
Micro-propagation is a relatively new propagation method and it involves asexual propagation of plants undertaken in laboratories or sterilized growing rooms. Similar to cuttings, roses propagated using this new method are made to grow on their own roots. Prior to the discovery of this method, botanists and biologists were of the view that it was only possible to develop roots and shoots when they are grown from the plant's real growing parts. Precisely speaking, micro-propagation is one form of tissue culture, involving removing a small part of a tissue or may be even a solitary cell from any axillary bud or a growing point and invigorating the part or cell to generate further grow points, which again generates more growth and the process continues.
Initially, the newly developed shoots do not have any root and, hence, they are stimulated by means of adding root-stimulating hormones that occur naturally to the medium wherein the shoots are being grown. When the roots develop, the petite plants are grown for a specific period and subsequently accustomed to growing in common compost in the world outside the laboratory.
This form of propagation is not only new, but also practised now and then. It will still take some time for micro-propagation to become popular and used widely for generating roses commercially. In fact, the most difficult part of this method is getting the new plants accustomed to grow in ordinary soil. However, currently scientists are engaged in further research and it is expected that they will come up with new and easier ways to wean the plants into common compost and soil.
It is important to note that micro-propagation is not suitable for all rose varieties, as not all types can adjust themselves to this new method of propagation. For instance, roses like Floribundas and Hybrid Teas generally don't grow properly when grown on their own roots. In fact, they grow better when budded; while a number of shrub roses grow even less well on their own roots compared to the two varieties mentioned above. On the other hand, several Procumbents and Miniature roses thrive better in ordinary soil and compost even when propagated by means of micro-propagation. Perhaps, this is owing to the fact that the plants generated through micro-propagation actually give rise to many addition roots from their base during the first year of their existence compared to the plants that are propagated from cuttings or by budding.
Micro-propagation, however, has one significant advantage. Plants developed by micro-propagation actually grow roots very fast. In addition, you just need a solitary cell or a small part of a tissue from the parent plant to produce numerous plants. If breeders take advantage of this new and unique propagation technique, they can not only produce large number of plants at one time, but also introduce new rose cultivars faster than the traditional methods of propagation. Nevertheless, this propagation method is seldom used, as it requires a lot of perfection and care.
It is possible to grow bare-root roses at any point of time during their dormant season. If you are living in the northern hemisphere, you can plant these roses any time between the fourth week of October and March end. However, you should never plant them when there is heavy frosting or chances of heavy frosts.
Bare-root roses, or for that matter any variety of rose, have a preference for fertile, deep, heavy loam soil. However, they will also grow well in moist soils, provided you do some added after care. At the same time, gardeners having a light and sandy soils or chalky soils should not worry. They can also grow and enjoy beautiful blooms, provided they take some additional care while selecting the rose type and range for their gardens. Generally, the unwritten rule is that you should select robust rose varieties for gardens having light soils. If the pH level of your soil is anything between 6.5 and 7.5 and has a reasonable depth and you take sufficient care of your garden, roses should normally thrive in nearly all conditions.
Here is an important piece of advice. Add enough organic materials to the soil when you start growing a new rose. It is best to provide the plants with properly decomposed farmyard manure. However, if you are unable to procure farmyard manure, you can also do with a mixture of bone meal and peat moss. Add a handful of bone meal to one bucketful peat moss, as this will be a suitable substitute for manure.
Irrespective of what you use, it is important that you blend it properly with the soil prior to planting your rose. In addition, you should dig the planting hole wide enough so that it accommodates the rose without having to constrict its roots. The planting hole should also be sufficiently deep so that the union - the junction of the roots and the shoots, is comfortably positioned no less than 1 inch (2.5 cm) below the level of the ground. After planting the rose and refilling the hole with compost and the soil you had dug out, press the soil gently with your feet, as this will help to remove all air pockets, if there are any. Use a few more spadeful of soil to cover up the footprints as well as to provide an excellent tillage in the region of the rose. You may also provide a top-dressing of proprietary (patented) rose fertilizer or bone meal with a view to help the plants have a robust start.
The distance between the rose plants should differ depending on the rose type. However, majority of the contemporary Floribunda and Hybrid Tea rose varieties grow optimally when they are placed at intervals of about 24 inches (60 cm) from each other. On the other hand, shorter roses will grow well even when the distance between them is about 18 inches (45 cm), while you can plant a number of Miniature and Compact Floribunda varieties even closer.