October and November are the months for pruning roses in Bangladesh and preparing them for the new flowering season. According to the rose cultivation guide of the Agriculture Information Service (AIS) under the Ministry of Agriculture, the rose is a winter flower but is now grown all year round. The main rules for light, water, feeding, pruning and pest control are set out below, from the AIS guide and two US university extension services.
Light, soil and water
AIS says roses do best at 22 to 30 degrees Celsius in well-drained, fertile loam with a pH of 6.0 to 6.5; clay soil does not suit them. Pots should stand in an open spot that gets at least six to eight hours of sun, including the morning sun. The plant needs light from all sides, or it will grow only towards the light, so the pot should be turned from time to time.
Water according to the soil, and never let water stand around the base. Plants need a little more water when new leaves and buds appear.
How to feed roses
The main feeding rules in the AIS guide are:
- For potted roses, start feeding a month after the plant takes, then every 15 days to a month.
- After winter pruning, give each pot three handfuls of powdered cow dung and one handful of steamed bone meal.
- Instead of chemical liquid fertiliser, cow dung and mustard oilcake soaked in water for four to five days can be given at the base twice a week.
- Roses in beds are fed once at pruning in October and again at the end of winter in March; feeding 10 to 12 days after pruning works better than on the day.
- One spoonful of powdered lime dissolved in a litre of water and strained through thin cloth can be given every three months; for 15 days afterwards, give only water and no other fertiliser.
AIS warns that chemical fertiliser is best not used without knowing the correct dose and method. Ask the upazila agriculture officer how much TSP, potash or foliar feed to use.
When and how to prune
AIS names October and November, after the monsoon, as the best time to prune. Use sharp secateurs or a knife so the stem is not crushed, because a crushed cut lets fungus in.
AIS describes three kinds of pruning. Light pruning removes a third of long branches, or only dead and sick wood; moderate pruning leaves 30 to 35cm above the soil; hard pruning leaves 14 to 20cm. Repeated hard pruning can kill roses in sandy soil. AIS advises covering cut ends with pruning paint, or cow dung on local roses, to keep out insects and fungus.
Oregon State University Extension advises removing dead and diseased canes first and cutting back to white or pale green live pith. A clean 45-degree cut about a quarter inch above an outward-facing bud keeps the plant open and reduces disease.
Controlling pests and diseases
The main pests named by AIS, how to recognise them and how to manage them without chemicals:
- Red spider mites suck sap from the underside of leaves, leaving pinprick marks and fine webbing. Act while numbers are low; a strong spray of cold water also reduces them.
- Aphids feed on young shoots, leaves and flowers in January and February. The University of California's IPM programme says knocking them off with a strong spray of water early in the day is often enough, and lady beetles and other natural enemies feed on them.
- Thrips attack buds and young tips in the hot, dry weather of March and April, and flowers open shrivelled. Cut off and destroy affected tips and flowers.
Among diseases, dieback blackens branches from the tip downwards. Cut well below the affected part, burn the cuttings and wipe the secateurs with spirit before cutting another plant. Powdery mildew covers leaves with a white powdery fungus late in winter and stops buds opening; pick off and burn affected leaves and tips.
AIS also advises insecticide and fungicide before and after pruning and in heavy attacks. Before spraying, ask the upazila agriculture officer which products are currently registered and at what rate, and follow the label.
When to cut the flowers
AIS says roses for immediate use should be cut half open, and those for use a few days later at the bud stage. For cut flowers, take a long stem with a few leaves using a sharp knife, very early in the morning or late in the afternoon.
Photo: SAIDUL HASAN / Wikimedia Commons (CC BY-SA 4.0)
Sources: The Agro News, Agriculture Information Service (AIS), University of California Statewide IPM Program, Oregon State University Extension
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