Many gardeners wishing to include roses in their borders might be concerned about whether they are appropriate for a water wise garden.
In the past, the easiest way to solve this dilemma was to plant roses in the high water usage area of a garden, but roses can actually be grown under drier conditions. It’s all about which roses you choose, and how you plant and care for them.
Choose water wise roses
Research has shown that some rose hybrids are more resilient than others. The cushion-type ground cover roses that grow to knee height, with overhanging, arching branches that provide shade for their roots, are particularly suitable for hot, dry positions and require little maintenance. They include ‘Queen Mother’, ‘Memory Bells’, ‘Pink Sunsation’, ‘Salmon Sunsation’, ‘Cream Sunsation’ and ‘Water Wise Blush’.
Bush-type roses that thrive with less water are ‘Queen Elizabeth’, ‘Double Delight’, ‘Peace’, ‘Burning Sky’ and ‘Ingrid Bergman’. Roses that first grow upright before hanging over, such as ‘My Granny’, ‘Adele Searll’ and ‘Fiery Sunsation’, are also able to withstand hot conditions.
Roses with prostrate stems are more susceptible to heat and stem canker because sap flow is so much slower in horizontal stems compared to upright shoots, so avoid planting this type of ground cover rose.
Roses need at least six hours of sunlight daily. Planting roses in too much shade will result in long, slender plants that are top-heavy and weak.
• For each planting hole, prepare the soil well by adding three spades of mature manure or compost. This helps the soil to hold water.
• Add rose fertiliser and bone meal to the soil and mix it in.
• Add water-retention granules to the soil in the planting hole. Only use the recommended amount.
• Plant the rose bush with the bud union just below the soil surface and firm the soil down well before watering.
• Shape the soil into a basin around the new rose to allow the water to seep down to the roots instead of flowing away.
• Mulch the soil around the rose.
The roots of roses grow close to the surface and they like to be kept cool and moist at all times. The best way to do this is to keep the soil well mulched; this also saves water by preventing evaporation. Organic mulch is preferable to inorganic mulch. Peanut shells, pine needles, bark chips and grass cuttings mixed with compost are all options. Spread a 5 to 10 cm deep layer of the organic material over the rose bed and renew it regularly. Alternatively, you can plant a ‘living’ mulch of low- to medium-water usage ground covers.
Roses thrive in well-drained soil with an ample water supply, however, what sets them apart from some other water-loving plants is that they can adapt, eventually surviving successfully on very little water. This does not occur overnight – the roses need to trained to be water wise over a period of time.
To acclimatise your rose bushes, water them three times a week at the beginning of the growing season. If they are planted amongst water wise plants that require less watering, then water the roses individually by hand in order to conserve water. After about eight to 10 weeks, slowly reduce the frequency of watering to two times a week. After a further eight to 10 weeks, water once a week.
Water deeply rather than lightly – each rose needs a minimum of five litres of water a week at the final stage of acclimatisation. During particularly hot and dry weather, give the roses extra water. Spray against pests and diseases regularly as healthy roses are stronger than diseased roses. In June and July, water only once a fortnight.
Water wise techniques
Practice the following water wise maintenance techniques to enable your roses to thrive under drier conditions than normal.
• Irrigate correctly
Although roses do not mind receiving water from an overhead sprinkler, this is not a water wise practice because much of the water is lost through evaporation from both leaf and soil surfaces. Rather use drip irrigation directly into the soil. An added advantage of drip irrigation is that the water spreads in an upside-down cone shape, which forces the roots to search downwards for the water at a level where the soil is cooler.
The quantity of water delivered per hour by drip irrigation can be fairly accurately determined, depending on your irrigation flow rate – it is usually between four to eight litres. Most roses flourish with about 10 litres of water per week and it is fairly easy to organise your system to apply 3,5 litres of water per plant three times a week.
A drip irrigation system is also the best system for roses in containers. These roses need watering every second day and the soil should never dry out completely, even in winter.
If you have already installed an overhead watering system, try to ensure that as much water as possible is given directly to the root area. This may mean repositioning the sprinklers. Water at the coolest times of the day to minimise the amount of water lost through evaporation.
• Fertilise properly
Fertilising keeps roses strong and disease-resistant as well as promoting bloom production. Between September and April, fertilise once a month with a fertiliser formulated specifically for roses. Give small and newly planted roses a teaspoonful, sprinkled evenly around the plant. Give the larger varieties about 50 g (about a handful), which you should spread over the soil surface around the plant, covering an area of 0,5m². If the roses are planted close together then one handful is enough for two roses. Note that the soil around plants should not be bone dry when you fertilise, and water well after fertilising to prevent fertiliser burn.
Well-rotted manure and good compost are both superb organic fertilisers and they also act as excellent mulches. Apply either by covering the entire bed with a 5 cm thick layer, but don’t allow it to touch the stems.
• Spray regularly
Regular spraying helps to keep the foliage healthy and strong. Keeping the rose bush covered with leaves is very important, for both ‘normal’ and water wise rose growing. The leaves keep the plant cool, which in turn makes it healthier and more productive. Spray preventively and regularly against black spot as well as red spider mite.
• Prune lightly
The water wise approach is to keep as much foliage on the plant as possible, which means avoiding cutting off spent blooms or twiggy growth during the growing season. Good fertilisation (which encourages root growth and keeps the plant healthy) rather than heavy pruning is the water wise way to produce good blooms. Admittedly, the result will be a bush with many short-stemmed, small flowers, but there will also be a normal supply of quality stems and blooms at various intervals.
Article by Ludwig Tashner