Roses And Soil
Plants use the soil for anchorage and for sustenance. The soil in which the rose is planted will determine how well your rose grows. A basic understanding of how soil works is essential in managing your garden. Soil is not simply a medium to pour bags of fertilizer on. Rather, soils are complex, dynamic, living systems that react to the changes we create.
They say that roses must have a clay soil to grow to perfection. This emphasis on clay soils is a bit misleading. Clay is consistently recommended mostly because of its ability to hold more water, thus making it less likely that the rose will dry out. Dry rose bushes do not flower or grow well. Another reason clay soils are recommended is because most roses are propagated by budding the desired variety onto a rootstock. Usually the rootstock is either Rosa multiflora or Rosa canina, species that grow best in heavier soils. However, many of the roses that the northern gardener plants, such as the rugosa rose and Scotch rose, actually prefer lighter soils when on their own roots. The important point to remember is that roses must have a consistent supply of water and nutrients to grow to their potential. Virtually any type of soil can successfully grow roses if it is well drained and has enough organic content for good water retention and nutrient supply.
A number that usually falls somewhere between 4.0 and 8.5, the pH is a reading of the relative acidity or alkalinity of your soil. The lower the number, the more acidic the soil; the higher the number, the more alkaline the soil. The pH is important because rose roots cannot absorb nutrients from a soil that is too acidic or too alkaline. For most roses, a soil pH anywhere between 5.5 (moderately acidic) and 7.0 (neutral) will produce good results.
If you live in the West or Southwest, or even parts of the Southeast such as central Texas, you may find that your soil is distinctly alkaline and that its pH is higher than 7.0. One way to cope with this is to plant China roses and tea roses that have been grown on their own roots. These two classes of roses are more tolerant of alkalinity than most other kinds of roses, and they thrive in soils whose pH lies in the range of 7.5-8.0. If you are planting grafted roses into alkaline soils, make sure that they have been grafted onto the rootstock known as 'Dr. Huey', since this, too, is alkaline tolerant.
If you wish to plant other kinds of roses, or if your soil is more alkaline than 8.0 (which is unlikely), you will be obliged to adjust your soil's pH, adding sphagnum peat or sulfur to reduce the alkalinity. The amount of these remedies will vary with the type of soil and the intensity of the alkalinity, but your soil test results will include a detailed prescription.
You should realize that this treatment is not permanent, since alkalinity will gradually seep back into your garden from the surrounding soil. And be sure to check the pH level of your tap water with your water company. If it is alkaline (it is likely to be, since the water in reservoirs and wells is filtered through the local soil), you will restore a small measure of alkalinity to the garden every time you irrigate. In any case, you should retest the alkalinity of your soil every year or two.
In the Northeast or Northwest, your soil pH is more likely to be too low -that is, too acidic. You can correct this by digging in ground limestone. Again, the amount of limestone you must add will vary with the type of soil and the degree of acidity, and the best prescription is the one you will receive with the test results. Acidic soil also requires periodic retesting, especially if you live in a region afflicted with acid rain. Continual use of chemical fertilizers will also tend to acidify the soil.
Soils are divided into two general classifications: clay soils and sandy soils. Clay soils contain a high percentage of minerals such as mica and feldspar. These minerals are made of tiny, flat plates that adhere closely together, making it difficult for water and air to penetrate between them. To break up a clay, it is necessary to mix in large amounts of coarse-textured organic material. These odd-shaped chunks hold the clay particles apart, creating spaces in which water and air can circulate. Because most roots grow near the surface of the soil, it is best to work most of your organic material into this layer. Here the roots will benefit from the increased oxygen supplies and the nutrients that the break down of the organic matter creates.
Sandy soils have the opposite problem. Sand soils are composed of grains of silica, or quartz. These are irregular and have spaces between them that air and water can pass through freely. If there is little organic matter in a sand soil, it dries out quickly.
Water passing slowly through a clay soil dissolves the surfaces of the mineral particles, releasing elements in the process. The particles of a sandy soil, however, do not dissolve easily in water because of their composition. As well, the rapid passage of water through sandy soil tends to quickly drain away what few available nutrients there are. For these reasons, sandy soils tend to be less fertile. However, the addition of organic material can rapidly solve this problem. Indeed, some of the best soils in the world are soils composed of sand and fine organic particles. The combination of good drainage and the nutrient- and water-holding capacities of the organic matter create excellent conditions for good growth. As well, loose soils composed of sands and gravels are easier to work with than clay soils.
Most garden soils lie somewhere between the extremes of pure clay and pure sand. In any case, the solution for improving your soil lies in the addition of organic material. Organic material comes from the bodies of plants and animals. When broken down by the soil's microorganisms the elements contained in them are released and combine with water percolating through the soil. This nutrient-laden "soup" feeds your roses. If you examine the roots of a plant, note how the fine roots work their way through the pieces of organic material. They know where the "soup" is being served.
Two well-known sources of organic matter are manure and compost. Another valuable soil conditioner available to most gardeners is peat moss. Its fine fibers have been chemically pickled by centuries of immersion in very acidic water. Although it contains few nutrients, it breaks down slowly and helps hold both water and air effectively in soil for many years. Shredded bark and other forest -industry byproducts are also valuable.
A clean cultivated garden is an unnatural and often hostile environment for a plant. In hot, dry weather it becomes a desert; the surface absorbs and gives off immense quantities of heat and loses moisture rapidly. Rains can cause erosion, and the surface layer can become packed from the impact of raindrops. After a rain, the sun can bake the muddy soil into a hard shell, reducing oxygen levels in the root zone and leading to even worse erosion problems in the next rainfall.
Most plants prefer a "forest floor" type of environment. In a healthy forest, the mulch layer is an equalizer. A mulch on your garden acts in the same way. Its insulating qualities temper the heat of summer and the cold of winter. Mulch absorbs and disperses the impact of falling raindrops, eliminating erosion and preventing soil bacteria and fungi from splashing up onto plants where they can sometimes cause problems. The continual activity by worms, insects and other life encouraged by mulch also creates a network of pathways, which increases the availability of oxygen to the roots. Perhaps most important, an organic mulch provides a flourishing environment for the numerous insects and microscopic plants and animals that are necessary to a healthy soil. Organic matter is continually broken down in such an active community. This breakdown of organic matter releases nutrients into the soil where it can be used by flower roots.
Whenever you add a large amount of organic material to the soil, it is important to realize that the breakdown of that mulch will require nitrogen. Nitrogen fertilizers will provide this, although at the expense of some of the soil's microscopic life. However, if a good quantity of well made compost is incorporated on the surface just before adding your mulch, it will provide enough nitrogen and will further improve your soil's texture and fertility. If the mulch layer is not worked into the soil, the nitrogen requirements will be smaller. Once this mulch "stabilizes," simply add new mulch on the surface every year or two and the system will not overtax nitrogen supplies. This gradual layering mimics the annual addition of leaves to the forest floor.
Weeding begins before you plant your first rose. If you are starting with a new piece of ground, the first order of business is to remove as many perennial weeds as possible, being sure to remove the roots to prevent the weed from regrowing. Although it is not exciting work, every hour you spend preparing your site will be repaid many times over in the future. Once the initial preparation is complete, you may want to add compost or manure. Once you have planted your roses, seriously consider mulching with a layer of organic material such as shredded bark or other materials that do not contain weed seeds. Many seeds need light to germinate, and the mulch will prevent light from reaching them. A thick layer of mulch will also keep many seeds from reaching the surface if they do germinate. Some will always manage to make it to sunlight, and any perennial roots that remain will send up shoots, but these are easily pulled in a mulched garden, an advantage that will be appreciated by those who have had to cultivate hard, baked ground, in which the weed roots are nearly impossible to remove. A mulch keeps the ground looser and better aerated, making it easy to remove both the top and the root of the weed.
When planning your garden, remember that an isolated flower in a lawn is difficult to maintain. Grass moves in quickly, and keeping your plant free of weeds can be a chore. If you can plant in groupings or beds, you will be able to keep the ground between the flowers more easily cultivated. This makes lawn mowing much easier as well. Rather than having to push under a bush from all sides, the mower can simply follow the edge of the bed. This edge should be cut with a spade each spring to prevent grass or other weed roots from moving into the bed. Leave a cut face at the edge; this will tend to "air prune" any roots moving toward the bed. If your garden plan calls for individual plants on the lawn, keep the edge of the cultivated area away from the flowers. This will allow you to easily maintain that edge.