Can Mini Roses Grow in Cold Weather?

Growing in Height

• Miniature roses grow best when daytime temperatures are around 70 degrees and nighttime temperatures are above 60 degrees, according to the Iowa State University Extension. They can still grow taller (up to their maximum) height at slightly lower temperatures, but the growth will be very slow. This is because the metabolic processes need warmth, and the plant must produce both the heat and the process itself. The growth at this time is also slowed by the defenses that the plant builds to ensure that any new growth is protected from cold temperatures.

Flowering

• Temperatures below 50 degrees don't damage miniature roses, but budding and flowering will slow or stop altogether. Immature buds may even drop, since the plant considers these low temperatures indications that it is time to go dormant, and flowering takes up too much energy to sustain. The plant will not have the energy to produce the seeds that should follow the fertilized flowers, so the plant protects itself in favor of trying to reproduce once temperatures warm again.

Cold Hardiness

• Although low temperatures will slow or stop growth, they rarely kill miniature roses. Miniature roses are fairly cold hardy, and can even survive freezes if they are well-mulched, watered and, preferably, covered. The upper portions of the plant may die and the roots will cease to grow, but warming soil will bring the roots back out of dormancy to produce new canes. For this reason, it's a good thing that most miniature roses are grown on their own roots, so they will come back true from dormant roots.

Considerations

• Even at low temperatures (50 to 60 degrees), it is sunlight that will influence growth rate most. Many gardeners grow miniature roses indoors because their size allows it, but there's usually far less sunlight indoors. Even in a cold home in the winter, if miniature roses have access to full sunlight and temperatures well above freezing, they will often still grow, if very slowly.