Most of the mini roses you buy in the store are Florist roses, there is no guarantee that they will live for very long. I have seen exceptions. I have tried growing roses in a sunny windowsill – it must get at least 4 hours of sun a day, and you would have to water it at least one to two times per week. I would also take it outside and spray it with a fungicide/pesticide once a week, even indoors they can get bugs somehow and develop powdery mildew. Or, you can grow it outside, if you live in a temperate zone, in part-shade, again checking about every day for dryness.
I think mini-roses do better outside in part shade with about four to six hours of sun a day, then they would do inside in a sunny windowsill, but as I have said it is up to you. Usually mini-roses are grown on their own roots, so in a deep freeze, even if the top growth died, they could still grow back from the roots in the springtime. You can protect them from deep freezes by covering with a plastic tarp or a cold frame, do an internet search to find good deals on cold frames or mini/small greenhouses.
If you decide to buy more mini roses, you might try some designed for garden use, like End of the Rainbow, Rise N’ Shine or Green Ice. Some other hardy varieties are: Antique Rose, Millie Walters, and Magic Carrousel which you could purchase from most Nursery. Jeanne La Joie is a miniature climber, and it grew to about 10 ft. tall. But, this is the exception, not the rule.
Most mini’s don’t grow that much larger in the ground than they do in the pot, at most maybe twice the width and a few inches taller. Some stay the same size. Again, it depends on the type of mini. You can do a search on the Help me find roses website. If not you can go to your local nursery and talk to them about getting roses.
Miniature Roses, also called Dwarf Roses, can be charming little plants with tiny leaves and flowers that are much smaller than Hybrid Teas. They vary in size. Some are only six inches tall when full grown. Some grow as large as 18 inches. They can be used as border plants, or as edgings because of their small size.
Possible red-flowered hybrids include Baby Masquerade, Beauty Secret, Dwarf King, Little Artist, Magic Carrousel, Midget, Red Cascade, Red Imp, Red Gilardi, Scarlet Gem, Starina and Tom Thumb – just for starters. But that’s not important.
First things first. When a flower is finished blooming, when it no longer looks like a flower you would want to cut and put in a a vase in the kitchen, cut it off with a scissors. Don’t let it turn brown, and then go to seed. Remove it. You can try planting it in the ground, the sunniest space in the yard is best. Roses need huge amounts of sun.
I highly recommend "Roses for Dummies." There are several pages specifically about Miniature Roses. You will find it informative and a very good introduction to a field that can be a little overwhelming to a newcomer. Pay extra special attention to your planted minirose in the autumn. There is a good chance it is not strong enough to survive our Zone 7 winters, even with Global Warming. Mulch carefully or cover with Burlap to keep it protected. If you don’t want to buy a book then go to a nursey or to someone that loves to garden, friends or a family member.
I know they call them indoor mini roses, but they really are happier outside. A mini rose is no different than a garden rose and likes the same things. The atmosphere in a home is too dry for these small roses and it not only dries them out but also incourages spider mites which love a place that is dry and warm. The first thig to do is cut the rose back so that all the dry tips are cut off. Put the pot in a plastic bag, tie it tight at the base of the rose and then place it under a warm spray in the sink. Make sure that all the rose is soaking wet as spider mites hate water. Do this daily for three days.
Repot the mini into a larger pot using packaged soil so you know there will be no insects in it. Put a tespoon of some slow release fertilizer such as Osmocote 14-14-14 and that will give the plant a small amount of nutrients every time you water it. Place the mini in full sun and every day sprtiz it with water. Make sure the rose never dries out but don’t get it soaking wet, just damp to the touch. The leaves may still drop for a couple of days, but they will come back nice and green and the plant will bloom for you. Putting the rose outside where it only gets morning and late afternoon sun also makes it healthier.