Perennial plants come back year after year so it’s essential to keep them happy. Here are Sandy Ovenstone’s top tips on caring for perennials in your garden

  • Soil preparation is important. “Perennials live for a long time and need nourishment,” she says. “Before planting we dig the bed to about 60cm deep and add compost; we also test the soil regularly.”
  • Plant in groups. “It’s tempting to buy one of each type of plant, but I don’t believe you can achieve the same effect, even in a small garden, with only one or two. You need to group them,” she says.
  • Plant according to height. “Use tall perennials at the back of your border and plant them in masses so they don’t look spindly. Alchemilla mollis is good in the very front and phlox in the middle.”
  • Don’t battle the odds. “Choose plants that grow in your area and your climate. There’s no point in struggling to grow things.”
  • Structure is essential. “Hedging is a good way to add structure. Visually hedges hold everything together and look great even without flowers.”
  • Perennials are an investment. “Divide them every year; it makes for stronger plants,” she advises. “Perennials tend to grow outwards from the centre so that the strongest plants are on the edges, while fewer flowers might be produced from the middle. Cut or tease off new growth and throw away the centre.”
  • The advantage of dividing perennials is “that you can get rid of weak stock, get weeds out of the roots and can redesign your border each year”.
  • A computerised watering system is essential. However small your garden, this saves water and prevents under and overwatering of certain areas. “If you have a strict routine of watering on certain days and times only, you’ll be surprised how your plants adapt and survive,” she says.