There was a time, many years back, when I used to collect miniature roses. There are literally hundreds of varieties, with single, semi-double or double flowers, perfumed or not, in every color of the rainbow except blue and I had about 20 in my collection.
The idea behind a miniature rose is that you want a plant that looks like a standard shrub rose, but much smaller, and with leaves and flowers in perfect proportion to the plant’s small size. For once, large flowers are a no-no. Theoretically, a miniature rose can grow up to 3 feet (90 cm) tall if it has thin stems and small leaves and flowers. However, most gardeners prefer really tiny ones. If any of mine grew taller than 1 foot (30 cm) in height, for example, I’d always prune them back severely.
Miniature Roses as Gift Plants
Miniature roses are often sold as gift plants for Mother’s Day, weddings, birthdays, etc. And they do give wonderful results… for a fairly short time. Like most gift plants, they really were never intended to last long. If kept indoors, they start to decline after a few weeks and usually end up in the compost pile. Alternatively, you can plant them out as garden plants. In that case, they will likely recuperate and begin to flower again.
Miniature Roses as Houseplants
I grew my miniature roses as houseplants, under extra-strong light: at the time, 4-tube standard fluorescents (T12) in the winter (today, you could use the more intense T8 or T5 tubes or else LED lights) and as much natural sunshine as I could muster during the summer. I never put them outdoors to keep them from picking up unwanted pests and diseases.
They were, I have to admit, very capricious plants, needing, besides full sun or the equivalent, regular watering, enough to keep the potting mix evenly moist, high humidity (50% or more at all times), regular fertilizing and constant grooming: removing faded flowers, yellowing or diseased leaves, pruning (because most tend to grow too tall over time), etc.
Ideally, I should have given them at least a month of cold dormancy late each fall to simulate the dormancy they would normally go through outdoors. Temperatures down to 35˚ F (4˚ C) are ideal and they’ll even tolerate several degrees of frost. After a month of cold (and darkness, if you wish: no light is needed while the plant is dormant), bring them back into bright light and normal indoor temperatures and they’re soon in bloom again.
That said, I had no legitimate way of giving them cold dormancy in my apartment of the time. I just kept them growing year round and they did just fine.
Spider Mites Galore
Perhaps because I kept my plants indoors, out of contact with garden roses, but I never had serious problems with black spot, powdery mildew or other rose diseases. But spider mites (or red spider mites, Tetranychus urticae), that’s another story.
First of all, spider mites are so small and light they literally float on the air and easily find their way indoors, being in no way thwarted by window screens.
Secondly, they love indoor roses, proliferating with remarkable speed, causing leaves to turn yellow and drop off, drying up buds and flowers and covering the tiny plants with their silvery webs. You could literally see them, dozens at a time, like little spots of dust wandering all over the plants.
Spider mites proliferate on stressed plants and are particularly happy in dry air and excessively warm temperatures, especially when the plants are over-fertilized (also a stress factor). In the average home, winter air is bound to be too dry and too warm for roses (which would rather be outdoors and fully dormant), so spider mites have free rein.
It’s not that controlling spider mites is all that difficult. I simply used to take my plants to the kitchen sink weekly and rinse them in tepid water: that’s all it took to knock the spider mite population back and allow my roses to thrive. But by the following week, the creatures were back. So, push the repeat button. All that rinsing just became an annoyance.
After a few years, I started getting negligent and began losing plants. (It doesn’t take spider mites long to kill a miniature rose!) Eventually my “collection” only held a few plants, possibly a bit more resilient than the others.
I solved the problem when we moved into our current home, simply by moving my miniature roses outdoors, into the garden. They make perfect plants for a sunny border and you can grow them in containers as well, as long as you water them faithfully and plant the pot in the garden for the winter. They’re hardy to zone 5 and do very well in zones 3 and 4 as long as you cover them in mulch (and I mulch everything: that’s just how I garden!). Most miniature roses (and all that I grow) are reblooming types and flower from the beginning of summer to late into the fall. And I’ve discovered that’s enough for me: I no longer feel any need to force them into winter bloom indoors.
In learning to be a laidback gardener, I’ve sometimes had to accept to let plants do what they want rather than what I would have liked and if going dormant in winter makes miniature roses happy, so be it!