By: Robert B. Martin Jr.
Can one grow roses indoors? This is a common question of the rookie rosarian who has falls in love with roses and may have had experience with house plants. The answer of course is "yes". Hundreds of millions of commercial roses are grown indoors in hothouses. But what about growing them in the home? Obviously the large roses pose formidable problems -- but what about miniature roses?
The answer again is "yes". Sean McCann in his seminal work on Miniature Roses, devotes a chapter to the subject. Charles Marden Finch, in his work "The Complete Book of Miniature Roses" devotes a third part of his book to the subject. Ortho, in its book "All About Roses" says that you can and major miniature rose nurseries such as Nor'East distribute "how-to" pamphlets on the subject. Although it may be argued that these sources address the subject largely to sell books or roses to the army of indoor plant gardeners, nonetheless it is clear that miniature roses can be successfully grown indoors.
But a more profound question for rosarians and indoor gardeners would, however, be "Is it worth it to grow miniature roses indoors?" Specifically one might inquire on how easy it is to grow miniature roses indoors and is the effort worth the result? The answer to this question, it is submitted, is a definite "no".
Of course the answer to any question of whether an activity is worthwhile necessarily involves individual value judgments which vary widely from person to person. There are many who, in recognition of the fact that growing roses is a time consuming activity, conclude, as to them, that it is not worthwhile to grow roses at all. Others feel it worthwhile to grow a few but find those such as myself who grow over 400 roses to be, to put it mildly, a wee bit daffy. Others simply like the challenge of doing the near impossible. To such people, perhaps the challenge of indoor miniature rose cultivation might be worthwhile; to the casual or even the serious rose grower the evidence suggests it is not.
In this regard it is appropriate to note at the outset that I do not attempt to grow miniature roses indoors. I have tried and those experiences are reflected in this article. I also know many serious and not so serious rose growers and can state flatly that I have never met anyone who grows miniature roses successfully indoors.
But this is not the end of the inquiry. "Why," you may ask, "is it not worthwhile to grow miniature roses indoors?" Or, if you are particularly tenacious, you might ask "How do you do it?" The answers to both questions are the same and are useful even to those who would never venture to grow miniature roses indoors because from those answers one can learn a great deal about the requirements of miniature rose cultivation whether indoors or outdoors. In this way we can all become better rosarians whether we ever try to grow roses indoors. Let us then consider the basic horicultural requirements of roses which touch on indoor growing.
1. A rose requries sunlight. Roses are sun plants and to perform well require some minimal amount of sunlight a day, usually six or more hours during the growing season. It will be observed, in watching the pattern of the sun, that depending on the time of year there are, perhaps, ten to fourteen hours of sunlight in a day. So a rose must be exposed to sunlight for at least half the day. In actuality experience will show that about three quarters of the day is preferable.
The problem with indoor cultivation is that by being kept indoors a rose is almost always deprived of adequate sunlight. A rose requires the light of the sun and normal indoor lighting simply won't do. Therefore, unless an artificial sun-like lighting system is established, an indoor rose must be placed in or near a window. But a window is simply a hole in the wall that admits sunlight only when the sun is facing the window. Since the sun moves and the window normally does not this can only occur during part of the day. Also the farther from the window the rose is, the less sunlight it will admit. The best indoor location is therefore a southern facing greenhouse window that projects from the wall and allows sunlight from many angles. Most indoors locations fall far short of this ideal.
2. A rose requires moderation in heat. Although roses love sunlight they are not equally fond of the heat generated by the sun. Roses growing naturally are found exclusively in the northern hemisphere north of the tropics. Here they receive plenty of sunlight during the growing season but the sunlight is of the long rayed variety, rather than the short hot rays of equatorial climates. Visitors to tropical climates such as Hawaii rapidly learn how fast the sun can burn; roses also can and do burn.
In addition a rose, as is noted below, requires a great deal of water which passes (or transpirates) through its system. Excessive heat forces water through the plant more rapidly and can cause the rose to transpirate water faster than it can take it up. The result is wilting, browning and other similar conditions.
The problem with a miniature rose grown indoors is that the indoors is usually warmer on average than outside. Obviously the indoors doesn't have the highs of the day, but neither does it have the lows. The result can be usually described as a uniform warmth. This problem is compounded by the window problem discussed above. As any child with a magnifiying glass soon discovers glass can focus sunlight to intense heat. As one moves a rose closer to the window to get more sunlight one also exposes the rose to this concentrated heat.
3. A rose requires water. It is said often that you cannot overwater a rose and this principle is worth repetition. Further the more constant the warmth the more water is required. Many, if not most, indoor plants suffer from overwatering (which is one reason they do so well inside). Many indoor gardeners are accustomed to going easy on their plants while watering. But a rose requires a lot of water and even the most assiduous of indoor waterers finds themselves away or otherwise occupied for periods of time when they cannot water. Outdoor gardeners can handle this problem with automatic watering systerms but this is technologically much more difficult indoors. Water is also much more messy to handle indoors where the overflow or drainage can spoil counters and floors. Indoor gardeners often handle this problem by placing saucers under their plants or using indoor wick watering systems. But his approach causes a problem with the next rose requirement to be addressed.
4. A roses requires drainage. Although a rose requires lots of water it like the water to pass through the growing medium relatively rapidly. The reasons for this are many. Passage of water leaves air spaces which permit the plant to breathe. It also passes nutrients by the roots and leaches out harmful salts and other substances. The need for drainage is the reason for the oft quoted and oft misunderstood aphorism that "roses do not like wet feet". Roses will not do well in standing water and perhaps one of the most effective ways of killing a container grown rose is to place a large saucer under the pot so that the standing water will rot and suffocate the roots.
The drainage requirement places quite a strain on the indoor gardener. Where is the drainage to go? The counter or floor is not usually a viable option. Instead one must use a large container with drainage space at the bottom or provide some other way to handle the drainage.
5. A rose requires space in which to grow. Perhaps one of the more annoying things to serious rosarians is to observe the number of miniature roses which are sold at county fairs, swap meets, and sometimes even by local rose societies, in very small two and three inch pots. Some are even placed into small bonsai arrangements to give the illusion that they have been miniaturized by bonsai technique. Although undeniably cute (look at the "baby" roses!!) this presentation gives the absolutely wrong impression that the plants will continue to thrive in such containers.
Most miniature roses require at least a one gallon container. Most require a larger container; my outdoor container of choice for miniature roses is a 7 gallon squat container. Normal size household containers are simply inadequate for miniature roses which rapidly become root bound and will perform very poorly.
6. A rose requires a lively loose soil. A rose is a heavy feeder, as are many houseplants, so the need for fertilizer can usually be met by a conscientious indoor gardener. However a rose cannot directly use the inorganic minerals on which it depends. Instead it requires the aid of lively soil organisms and bacteria to break down the fertilizer into a form it can use. Out doors these organisms are transported through the soil and air. The indoors is much more sterile and it becomes necessary in indoor cultivation to add organic matter to the soil on a regular basis. Here one often encounters the size limitations of the container.
7. A rose requires air circulation. Roses breathe through their leaves and the pores (stomata) in the leaves can become clogged with dirt and dust. As a result they like air movement which can prevent particles from settling. They also like an occasional shower to wash off their leaves which the rain or a thoughtful rosarian can easily provide out of doors. Indoors, however, this becomes a problem as it is more difficult to simply spray the rose with water. Indoors also has much less air circulation thus permitting small particles of household dust to settle on the rose and to suffocate it.
8. A roses requires protection from pests. It might be thought that the protection of the indoors might aid in meeting this requirement but the reverse is true. Granted it is more difficult for rose insects to sneak into the house, nevertheless the indoors raises more difficult problems in pest protection. Many pests thrive where air circulation is reduced. The chief pest for the indoor rosarian is the ubiquitous spider mite which affects many other indoor plants and seems to get inside without much effort. Spider mites love low air circulation and constant heat. They thus multiply rapidly indoors. Other pests face natural predators outside but are protected from such predators inside.
Spider mites can be controlled largely by directing blasts of water at the undersides of the leaves where they congregate. This is not easily done indoors where the water will get all over the furniture and drapes. One solution is to take the container to the sink and turn it upside down to wash of the leaves. This is easier said than done when dealing with the size of container that a miniature rose will require to do well.
The problem of spraying pesticides is also magnified indoors. Sooner or later all but the most stobborn environmentalist learns that you must spray to defeat rose pests. If you choose to spray inside you must address the question of how to handle the overspray of toxic chemicals and whether you really want to breathe this stuff indoors where it does not dissipate rapidly. Some indoor gardeners resort to the so called organic and safer sprays only to learn first hand how generally ineffective these products are against determined pests.
So there you have it. An understanding of the requirements of a miniature rose lead inescapably to the conclusion that it is very hard to grow miniature roses indoors. This explains why even the most dedicated lovers of roses rarely do so. If you don't believe it try it for yourself. You will be sorry you did.