I planted six rose bushes in summer 2017 in a spot that gets afternoon sun. They are a mixture of a few Parfuma roses and then about four David Austin roses. None of the plants have been growing well and I thought the late day sun may be too hot for the plants. I am considering moving all of them to a spot where they will get morning sun, but I noticed this fall that the two Parfuma rose bushes each sent out one or two very long and fast growing shoots. They are over 4 feet long and very healthy looking, HOWEVER, I'm concerned that they aren't helping the plant because the rest of the plant is still small and not bushy like it's supposed to be. I am looking for suggestions on how I should handle this and also if I should move all of the plants to another location please.
Roses as a general rule prefer morning sun over afternoon sun, but that is unlikely the only factor affecting the health of your plants.
Roses are most often
grafted onto a vigorous rootstock. There are many reasons for this and many benefits, but I’ll leave that topic for you to research separately.
The very long vigorous growth from some of your roses could be shoots from the rootstock. Photos of where these shoots originate on the trunk / main stem of the plant, will help us determine if this is the case.
If this is the case, these rootstock shoots will literally take all the energy for growth from the rose bush that it is supposed to support and feed.
There are many other reasons why your roses may not be growing as strong as you’d hoped. The following summary of tips may help...
Roses prefer their root system remain damp and cool with a minimum of temperature variation. This can best be achieved with a thickly applied mulch of any legume hay, such as pea straw or lucerne / alfalfa.
Roses prefer hot dry conditions for vigorous growth and flowering.
Roses suffer severely if fungal infections are allowed to prosper.
Roses are gross feeders and drinkers - they need a lot of well rotted animal manure and regular watering to maintain vigorous growth and flowering.
It seems possible the very long, fast growing shoots are suckers off the rootstock - there is an easy way to check whether they are not. They may look different for one thing; lots of thorns maybe, or a pale colour, obviously fast growth rate compared to the rest of the plant, but the way to check is where they originate from. If they're coming from below the graft (the lumpy bit at the bottom of the rose bush, just above the roots) then they're suckers - if they're coming from above that graft, they're not. If they're suckers, wrench them off at the point of origin, and keep a check ongoing - some roses are more prone to putting out sucker growth than others.
As for the growth rate, knowing where you are and what care regime (if any) you've been using in terms of rose feed/fertilizer, if you used a mulch and what kind of mulch, as well as when it's applied, and, if you live somewhere hot, how much water they've been given and how often. Also would be useful to know what soil preparation you did or didn't do prior to planting...and can you confirm there were no roses in that area which had been removed before putting in the new ones, please.