Caring for Your Hardy Roses

Wiese Acres north gardens at sunset

Even if you choose rose cultivars that are easy care and disease resistant, they still may need some special attention.  Choosing a rose cultivar that is reasonable for your location is number one on the list.  Then comes planting the rose correctly; followed by correct fertilization, watering and disease control; and finally, putting it to bed for the winter properly.

I start by choosing only cultivars that are hardy to zone 4.  I know that there are people in my area who bravely plant zone 5 roses, and even some zone 6.  But, then we are back to the “if it requires more nurturing than my children did…”  The next thing I look for is to make sure that the rose is grown on its own root, rather than as a grafted rose. 

 I have planted a couple grafted roses in my gardens over the years.  One of them was a gorgeous copper color, the other beautiful sunny yellow.  Both were absolutely loaded with large, wonderfully fragrant blossoms nearly the entire summer their first year in my garden.  “Ah, yes”, I thought when each of them put on their display, “this is a keeper”.   The following spring , each plant came back with beautiful foliage but was very slow to bloom.  They did finally bloom, and just imagine my dismay when my gorgeous copper and yellow flowers had become a dull, puny, blah-smelling pink.  The grafted portion of the roses, which produced the gorgeous copper or yellow flowers, had died out over the winter and left me with the flowers from the hardy root stock to which my prize had been grafted.  Now, there are only so many dull, puny, blah-smelling pink roses one needs in a garden so they both were replaced with own-root roses the following spring.

 How does one know if the rose is grafted or own-root?  Most own-root roses are identified as such on the plant marker.  If it is not, you can look for the graft union – a larger, bulbous looking area towards the root.  There will be the slimmer stalk of the hardy root rose below it and the stems of the grafted desirable rose above that bulbous area.  Sometimes you can see a stub of the original stem of the root stock sticking up just above the graft union, also.  Own-root roses will have a smooth, uniform stem all the way to the root flare.

 Now, all this doesn’t mean that you absolutely cannot plant grafted roses in your northern gardens.  It does mean, though, that if you want to keep them looking like the beautiful rose you purchased, you will need to give it some extra tender loving care at winter time, mulching the crown and the canes to protect them from the elements.

When purchasing plants, look for a nicely balanced plant with strong, thick canes and a good, solid root system.  Look for signs of disease or pests and opt to leave those at the store.  Yes, you can spray or otherwise treat them when you get them home, but unless you get a deal that just cannot be refused, like they are willing to pay you to take it out of their garden center, let them deal with their own problems and you go shopping for a healthy rose.

Next comes proper planting.  Roses need at least six hours of direct sun a day to do their best.  They will grow and bloom some with slightly less than that, but you won’t get the profusion of blooms with less sun.  They also must be planted in an area where there is good air circulation, so a protected corner of the house might not be the optimum location.  To tell if you are giving your roses enough space for adequate air circulation, look to see if overhead light is able to touch all sides of your rose.  If it does, then you should have adequate air circulation. 

Adding some organic matter to the top foot of soil in your planting area will be welcomed by your roses.  They require well-drained, light soil.  Most sources will tell you to plant the graft union or the crown about one inch below the surface of the soil, or in the case of potted roses, even with the depth of the soil in the container.  I think most gardeners who grow roses successfully in northern climates will tell you that is a rule meant to be broken. 

I plant my roses with the crown four to six inches below the surface of the soil.  That assures that they will be protected from frost heaving, freeze and thaw cycles,  and excessive cold.  It does not affect the growth of the rose, other than to make the appearance of the first foliage of spring somewhat later, but that is also a good thing in an area that is prone to late spring frost.

Roses like about 4 inches of organic mulch to keep the soil cool and evenly moist.    They do not like rock mulch so try to avoid that, no matter how much you might love rocks.  I guarantee you, that love will not be shared by your roses.  Rocks collect heat from the sun, transfer it to the soil, and the soil transfers it to your rose roots.  They also weigh down and compact the soil.  Imagine having your feet in uncomfortably hot water all day long, weighed down with a heated concrete block; finally the water begins to cool and you think you are going to get some relief, that your feet will finally cool off.  Then, someone comes and pours another bucket of boiling water over the concrete block in the foot basin and your misery begins all over again.  That’s what the sun rising and setting on the rocks around your roses does to their “feet”.

I create a ring around the stems of the roses using plastic lawn edging to keep the organic mulch from getting pushed up against the stems themselves.  Mulch too close to the stems fosters rot and allows pests and rodents to hide in the mulch while they have your rose stems for dessert.  I prefer cedar mulch because it looks and smells great, lasts a long time, and may repel some pests.

Roses need one inch of water each week to thrive and bloom their best.  Watering with a soaker hose is going to give you the best results.  Roses don’t like water setting on their foliage and are very susceptible to fungal and bacterial diseases if this happens regularly.  If you must use overhead watering, it is best done in the mornings so that the sun will dry the water from the foliage more quickly.

Roses can be fed with a slow release, low nitrogen fertilizer, such as a 10-20-10 formulation, in the early spring, as soon as you start to see growth.   Repeat bloomers should receive another application of slow release fertilizer right after the first bloom.  If you don’t use slow release fertilizers, roses should be fertilized with a 10-20-10 formula every month from first sign of growth in the spring through July.  Roses should not be fertilized in the fall – the first part of August is the latest they should ever be fertilized in this part of the country.  In other parts of the country, the rule of thumb is that your roses should have at least six weeks of time prior to killing frost without fertilizing to “harden off” for the winter months.

 If you buy disease resistant shrub roses, you are less likely to have trouble with diseases like black spot and powdery mildew, but in extreme conditions, even “resistant” varieties are not absolutely fool – proof.  Watch your roses for signs of infections or pest infestations and then treat sooner rather than later.

Come fall, if your hardy roses are well established and healthy, you probably don’t have a lot of work left to do with them.  If they are not reliably hardy for your area, or if it is their first year in the gardens, winter mulching should be done once the ground is frozen and all foliage has died for the year.  

You can use foam rose cones to protect your roses.  You won’t see any of these at Wiese Acres, though.  I find that with our clay soil they hold too much moisture, fostering the growth of molds and other diseases.  Not to mention the fact that, in spite of anchoring them down with rocks, bricks and other heavy objects, I often used to find myself doing search and rescue missions from the neighbor’s swimming pool after a good strong wind. 

I prefer good, clean wheat straw or leaves.  The wheat straw tends to stay in place better even if a good wind manages to find its way into the yard.  If necessary, I will anchor the straw with branches trimmed off the old Christmas tree when we are finished with it or other trimmed branches.  A couple of pieces of 2 x 4’s also do the job but must be placed carefully to avoid breaking the canes. 

You can trim the canes of the roses back some to make the mulching process easier, but shrub roses are best trimmed in the spring to promote the greatest flush of blooms.    When I do mulch roses for the winter, I tuck about 10 to 12 inches of straw in around the crown and the lower canes and just leave the taller canes exposed.  These help keep the straw in place and can be easily pruned down in the spring.

For more vulnerable roses, you can use the Minnesota Tip Method, where you tie the canes together, dig a trench deep enough and long enough to hold the entire rose, “tip” the rose down into the trench and cover the entire crown and canes with several inches of soil, followed by several inches of leaves or straw mulch.  In the spring, you dig the branches out of the trench and let it grow. 

If you’re like me and you love roses but just aren’t willing to do the work of growing the more “finicky” cultivars, there are some good options for us.  We can wander through our garden of hardy, disease resistant, tough as nails but beautiful as, well, as roses, plantings and enjoy what we have accomplished.