Roses have been loved and grown by gardeners for thousands of years. Native to most continents of the northern hemisphere (there are none native to the southern hemisphere), roses are one of the most diverse plant species.The range of colours and fragrances can be matched by few other species, in growth they can climb, ramble, be a ground cover, a miniature, pillar, weeping standard or a shrub. Some can live as long as 200 years.
Types of Roses
The Genus “Rosa” is made up of 11 groups of “wild roses” from which there are about 140 species. Three quarters of these are native to Asia, 18 to North America and the rest to Europe and North Africa. Keen gardeners and nurserymen have been breeding from these wild roses, creating thousands of hybrids over many centuries. The main types we sell and grow today are mostly repeat flowering modern roses. Roses hybridised from around 1900, include:
Floribundas English David Austins French Delbards Hybrid Teas
Climbers & Ramblers Landscape/Ground Cover Roses
BARE ROOT ROSES – as soon as you get home with your rose, open the plastic bag and remove the rose from the packaging. Place your rose into a bucket of water for 30 minutes to re-hydrate the plant.
PLANTING POSITION AND PREPARATION – Roses require 5-6 hours of full sun per day for best performance. Roses tolerate a wide range of soil types, but your garden bed must be well drained. If your soil is lacking in quality or drainage, mix a premium potting mix or mulch or your own compost into your soil. Dig a hole approx 500 x 500 x 300mm deep. Plant your rose halfway up the main trunk, do not cover the graft or the trunk where branches begin. Water in well. If winter rains do not occur, water your rose every two weeks. Do not feed your rose at this time. Feed during early spring with a well balanced slow release fertilizer.
POTS – When growing roses in pots a good balanced slow release fertilizer is needed which covers NPK plus trace elements. Granular foods such as Green Jacket or Osmocote can last up to 9 months when used at the correct rates.
ROSES IN GARDEN BEDS – Can be fed with a large range of plant foods, depending on the size area you need to feed and cost. The above granular foods are good, but if you have a large garden this can be too expensive. This is where organic foods are used. Pelletised chook manure, blood and bone, hoof and horn and well aged horse & cow manures are excellent. But remember they usually last about 3-4 months only. These organic foods are much more economical for the home gardener and also encourage worm activity in your soil. Do not place manures up against the truck of your rose, place just around the outer foliage area.
Make sure you mulch your roses for Summer to reduce water loss and preventing weeds while adding nutrients. Mulches can be purchased by the bag or truck load at large retail nurseries. Lucerne and Pea-Straw are also effective mulches that breakdown offering some nitrogen to your roses.
Pests and Diseases
Fungal diseases in roses are due mainly to weather conditions and the variety of rose that you have. Cloudy, wet, humid weather is the precursor for the 3 main funguses to thrive. Black spot, Powdery Mildew and Rust.
The variety of your rose is also important as they can vary in disease resistance from hardly being effected at all ie: the Rugosa family of roses which are very disease hardy roses, to very disease prone most of the year. Most breeders are now aiming for high disease resistance in their breeding programs so hopefully each year roses will become even easier to grow. Your average rose is susceptible occasionally during a year and at other times can be quite free of disease e.g. Iceberg, Grimaldi, Bordure Rose, Guy Savoy are quite hardy.
Make sure your roses are in the correct position to start with – 5 hours of full sun per day, well drained soil and an open position ie: not under trees or up against other shrubs. Treatment of funguses is like treating human diseases in that if you keep treating them with penicillin, the human diseases will become resistant. Plant funguses are the same. Keep using one chemical for a year and you may get no control the following year. I always mix a preventative with a curative chemical, if possible, to broaden the control.
BLACKSPOT – purple blotches on leaves
Control – Mancozeb (preventative) and Triforine (curative) – Baycor is another good curative
POWDERY MILDEW – white powder all over buds & stems
Control – Baycor in warmer months.
RUST – orange dots on leaves
Control – Mancozeb and Triforine or Zineb.
DOWNY MILDEW – Die back. Black stems spreading down from the top.
Control – Ridomil Gold is a good treatment but if the die back goes too far, dig out rose and burn it so it does not spread to your other roses.
MOSAIC – virus yellow flecks or variegations in leaves.
Control – These plants should also be dug out and burnt, if the yellowing is overtaking the rose.
APHIDS – small green or light brown bugs usually covering flower buds
Control – Small outbreaks – Pyrethrum based sprays as they are the safest.
Major outbreak– Folimat or Confidor will stop them in their tracks.
TWO SPOTTED MITE – sucking insects which live under the leaves, turning them a mottled brown
Control – Winter – Lime Sulphur (kills mite eggs) & Winter Oil (use separately) to smother any eggs.
Summer – Pyranica will kill the adults. For Biological control, Predator Mites which consume Two Spotted Mites.
Control – Confidor. For biological control, use Dipel.
THRIP – tiny black, thin insects about 1mm long that arrive with the Summer heat.
Control – Orthene.
SCALE – tiny white shell like insect stuck to the stems and branches of roses.
Control – Non-chemical control can be gained by spraying of winter oil during the winter months. Confidor is also a good systemic chemical.
CAUTION – All chemical sprays should be treated with care. Read & observe all instructions on the bottle. Wear protective clothing, gloves and a mask when spraying. Keep all chemicals locked up and keep out of reach of children. Do not spray on windy days.
Much has been written about Rose pruning over the last century, and often this information is very technical and sometimes confusing to the novice gardener. After 20 years of growing roses commercially we have gained great results with simplified pruning methods in Summer & Winter rose prunings. This is a general guide to these methods for our modern roses (not old world roses – non repeating & specie varieties).
There a 3 Golden Rules for Winter Pruning –
1. Cut back your rose 50% in a rounded shape, whether old or freshly bought from your nursery.
2. Cut out any wood less than a pencil thickness.
3. Cut out any dead wood also.
That’s it! Do not open up the middle of the plant in a vase shape or worry too much about crossing over branches. Modern roses are very vigorous and when grown in the correct position and looked after well, shall re-shoot & grow better with plant material left inside the framework than if it is cut out in the vase shape. Every 3 to 5 years, if your rose bush is looking terribly woody and too many branches, you can remove any old very thick branches with a saw. This will to reduce the excess wood and encourage new water shoots.
LOOK OUT FOR different coloured flower or foliage growing out of your rose. Most understocks (the rose your variety is grafted to) is either Dr Huey or Multiflora. The former has deep red cluster type flowers and Multiflora – white cluster type flowers. Both can send up a water shoot 2-3 metres in a matter of weeks during summer
Summer pruning has one Golden Rule –
Cut your roses AFTER EACH FLOWERING has finished by one third, using hedge shears into a rounded shape.
That’s it! These repeat flowering roses shall re-flower within 6-8 weeks en masse. So you can time them to re-flower for your own special parties or events. Again vigorous roses shall re-grow easily if they are healthy and growing in the correct position i.e. 5-6 hours sunshine per day!
Standard Roses – We recommend to cut back by 50% each summer prune so they do not get too large on top of the standard stem.