12:04pm

Fri December 9, 2011
Garden Report

Time to Protect Roses for the Winter

There is snow on the ground.  The temperatures the past week have been cold.  The soil along the Front Range is frozen.  It’s time to protect roses for the winter.

Grafted roses grown on the High Plains need winter protection.  Temperature extremes from below zero degrees one week and sixty-five degrees the next week take their toll.  Desiccating winds suck the moisture out of exposed canes.  Just a little insulation keeps roses alive. 

Roses go dormant on their own schedule.  It usually takes some hard freezes like we’ve had for them to lose their leaves.  Insulating roses too early causes problems.  Early mulching doesn’t stop the freezing and thawing cycle.  When the soil is frozen the mulch keeps it frozen.

The rose graft is the most important plant area to protect.  The graft is the bulge at the crown where the special named rose variety is attached to a hardy rootstock.  At a minimum, cover the graft with three or four inches of mulch, soil or compost.

Better yet, prune long canes to twenty-four inches above the ground.  Then mound insulating mulch, soil or compost over all of the canes.  The mound can be eight or ten inches deep. 

Grafted, climbing roses offer a challenge.  Some are definitely hardier than others.  If you’re growing a less hardy variety, the entire cane needs protection.  Un-trellis the canes and lay them in a garden bed.  This is a thorny, treacherous job.  Cover the canes with at least four inches of mulch.  The live canes can be re-trellised in early spring. 

Some grafted roses tolerate winter extremes better than others.  But without a lot of research and experience killing roses, it’s difficult to determine which roses are hardiest. Generally shrubby floribunda roses need little protection.  Most hybrid tea and grandiflora roses benefit from winter protection.  Winter insulation doesn’t hurt any roses.  Mound all grafted roses to be safe. 

Roses on their own root are another solution.  These varieties have no graft union that can be damaged.  The worst case scenario is, in a hard winter, the rose is killed to the ground.  The hardy root will re-grow in the spring with the same flowering plant you started with.  Many own root roses are selected for their disease resistance, flower color, fragrance and ability to survive the harsh Canadian High Plains.  Own root roses don’t need a bunch of extra care.  They can be treated like any other shrub in the garden but they have rose flowers.

 

tom@throgmortonplantmanagement.com

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