After de-heading, watering and feeding properly, your roses are already going to be toughened up against black-spot and powdery-mildew but as we get into the humid wet spring weather you will need to spray. If you have had it with black-spot then get hold of the Kendon Triforine. It is the best form of Triforine that we have tested and the feedback from our customers has been very positive. Its very simple and it is very effective. Simply mix 15ml per litre of water into a container that has never had any weed killer in it. (That is very important!)
Then start spraying around mid September when the shoots get around 10-15 cms long. Early spraying will ensure a healthy start to the season. Usually people only start spraying when they get blackspot and it is very hard to win the fight back once you have it. Remember - prevention is better than cure so get on the spray program early and after 3 to 4 months of regular spraying every 2 weeks you will have perfect roses all summer.
We don't like using insecticide and we only use it when those aphids thrip start to really do damage. We don't promote getting the insecticide sprays out if there are a few hanging around. In fact - some people actually comment on the odd aphids and thrip when buying flowering potted roses here during summer. We only get serious when they really start partying and then its time to break up their little get-together. Really - the only time we recommend you use insecticide sprays is when you have an major infestation of aphids or thrips. Aphids, (generally green in colour) occur in Spring and Autumn and congregate on the stems of roses.
Thrips however - (brown in colour and tiny in size) always appear in the heat of Summer on those hot days and humid nights. They are the ones that are attracted to bright coloured roses such as your whites and yellows. If these appear and you want to get serious with them, then mix some Pyrethrum, Folimat or Confidor insect killer in your spray container - again - that's the one that has never had the weed killer in it - remember. Once you have sprayed it all - rinse the container and do not store any leftover insecticide as it is dangerous and will not work after 24 hrs anyway.
Some people ask us how to get rid of caterpillars. We say - hunt them down your self and squash them! You would be amazed how easy they are to find and spraying them is useless as they are always hidden inside the rose buds. You can usually see their watery brown droppings on the nearest leaves - then look for the hole they have made. They are usually in there.