Many nursery roses come with generic 'instructions' on the tag, but they're short on detail. Not all of them are localised for our climate or conditions either. These tips are aimed mainly at the warm temperate climates common on Australia's coastline.
Many parts of Australia (including most of Sydney) are plagued by clay soil. Roses don't mind clay too much. They prefer it to sandy soil and it stops them drying out in the summer heat. On the other hand, you won't get good results in clay unless you try to improve the soil.
If you're working with an existing rose garden, it's safe to rake in the following materials at the top couple of inches of the soil. For new beds, dig it through the soil:
I've tried liquid 'Clay Breaker' products. If they worked at all, I never noticed. If you're adventurous give them a go, but otherwise save your money.
Sandy soils benefit from organic matter too. It aids in moisture retention. Because manures and compost release their nutrients more slowly than chemicals, they also help combat the fast leaching of minerals that happens in sandy soil.
If you're the organised type (unlike me!) you can prepare the soil as above, a month or two before planting. As an alternative, many nurseries have special rose planting mixes. I can't recommend them highly enough. The better ones have a fertiliser component that will get your rose off to a flying start without causing chemical burns to the infant roots.
The following steps will get most roses off to a flying start:
After you've improved the soil with manures or compost, do you still need to fertilise? You bet. I did go through an organic kick but it's no comparison with a combination of organic and chemical fertilisers.
Roses are big feeders. Be generous. Once a month should be a minimum between August and April. My personal regime involves:
If this sounds too exhausting, at least give the bushes a good dose of rose food in spring and sprinkle a lot of Osmocote around. The rose food will kick start the spring growth (when the rose needs it most) and the Osmocote will provide minimal ongoing feeding till the following autumn.
I've read all sorts of theories on watering. The Swanes theory is that you should give roses one or two deep soaks per week to encourage deep rooting and drought resistance. That may be true, but feel free to take extra pity if the bushes look like they're wilting- during December through February at least.
Overhead watering systems wet the rose's leaves. This can be a blessing and a curse. Wet leaves can deter some pests like mites, but it can also promote fungal diseases. Watering at root level reverses those factors. If all I'm applying is water, I put it on the soil. For Osmocote soluble, Phostrogen, Aquasol and Seasol I water the leaves because foliar feeding is an excellent way of getting nutrients into the plant.
If your rose bed isn't absorbing water, keep the soil cultivated. Don't let it form a hard crust. Use Wettasoil twice a year (it's great stuff!). Some soil improvers, including Organic Life and Dynamic Lifter Long Life, have zeolite (a mineral water softener often found in laundry detergent) that performs the same function.
This is almost a religious subject for some gardeners. Mulches, layered on the soil surface, are supposed to improve the soil, keep the roots cool in hot weather, and retain water. Many also smother weed growth.
I have had good results with lucerne (alfalfa) mulch. Swanes swear by it - they even have Gro-Cubes of mulch that include some added organic fertiliser. Cat owners can use a litter called Natty Cat that is 100% lucerne pellets - the discarded waste is fine on rose beds.
In the 2002 season I had one bed mulched with lucerne and the other bare. Roses in the mulched bed did do a little better, especially in the heat of summer. I couldn't judge any effect on disease resistance because I wasn't growing the same rose varieties in both beds.
Can roses survive in a mixed garden bed? Certainly, if you believe the photos of cottage gardens in the magazines. On the other hand, root competition is a factor for any plant and roses are no exception. If you want good results from roses, don't plant anything else within 40 cm of the main stem. I also space rose bushes at least 1.5 metres apart, although hybrid teas can probably be squashed in as close as 1 metre apart.
Some kinds of plant are supposed to help deter pests. Lavender, garlic, parsley and some other aromatic plants can confuse rose predators like aphids (or that's the theory). I've interplanted lavender between roses in one bed and it has no benefit at all - except looking pretty!
In Sydney and similar climates, pruning should be done in late July. Pruning in June can rob you of some of the nicest blooms that your bush can offer. Pruning also tends to prompt new growth, which will be stunted if it comes out in mid winter.
Pruning is not black magic. It's really pretty hard to make a mistake. A few gardening TV shows have tried to ease beginner fears by using hedge trimmers and chainsaws to prove how resilient roses are. I haven't been tempted to try those stunts myself.
The traditional wisdom was that light pruning produced more, smaller blooms while heavy pruning would produce fewer but larger flowers. Heavy pruning has basically lost credibility because it removes too much of a plant's ability to produce food for itself. The old-school Australian idea of a second, midsummer pruning lost favour for the same reason.
For normal pruning cuts, use clean sharp secateurs. Blunt tools bruise stems and allow infections to enter. Old woody canes will need a tree lopper or pruning saw.
For most hybrid teas, floribundas, hybrid perpetuals and David Austin roses, follow these steps. Here is a photo of a hybrid tea bush (Voodoo) before pruning. I chose Voodoo because it has thick stems that can be easily photographed:
Tea roses dislike pruning, probably because they don't go truly dormant in winter. Only cut what you need to keep the bush at a desired height. Don't wait until major cuts are needed because they will make the bush 'sulk' for months. The best control is to cut off spent blooms with longer stems throughout the season.