Watering plants correctly is one of the simplest ways to keep them alive, whether they’re growing in your garden or potted up indoors. Water and light are essential components of photosynthesis, the process by which plants convert light energy into chemical energy in the form of sugars.
All plants have this in common, but anyone growing roses will know that they are particularly thirsty plants and cannot solely rely on rainfall, especially in drier conditions. Diane Sommers, former president of the American Rose Society, says it’s why watering them enough and correctly is paramount to achieving a display of fragrant, showy blooms. She warned: “Water sitting on leaves for six or more hours may lead to fungal diseases.”
Black spot and powdery mildew are among the most common rose diseases that thrive in moist environments, so leaving foliage wet overnight increases the risk of infection.
Fortunately, the fix is simple, says Diane. She explained that the best time to water roses is in the morning, as the sunlight and wind help to dry off the foliage throughout the day.
The middle of the day sees the highest intensity of sunlight, leading to higher soil and plant temperatures.
Plants that are watered in the morning are able to absorb the water throughout the day when they need it most, while also minimising water loss through evaporation. There is one exception to this rule, however.
Gardeners growing roses in desert climates should wait to water them in the evening, as moisture evaporates too quickly during the day.
Diane said: “Unless you live in a desert climate, you should not water roses in the evening, as there is a good chance that water will stay on the leaves for many hours, increasing the opportunity for diseases such as blackspot.”
Roses grown in containers may dry out noticeably faster than those grown in the ground, so they may need watering more frequently.
Water container roses daily during hot weather and every two to three days during cooler weather.
Established roses are those that have been in the ground for a period of time and developed a strong root system and a healthy, mature structure.
“They should really only need watering during dry spells in high summer, when you should water up to once a week”, explained the Royal Horticultural Society.
One large watering can per plant should be enough. However, if the blooms or leaves start to wilt, then water immediately.
Whether you’re growing in-ground or potted roses, the goal is to keep the soil consistently moist but not waterlogged.
