Planting and maintenance

There’s an art to creating a colour-themed flower border in which many different plants peak at the same time, blending together harmoniously. Success hinges on choosing plant varieties that suit the situation in terms of soil type, aspect and position. Achieving ‘right plant, right place’ ensures healthy plants that bloom plentifully, and are less prone to disease. Soil health is especially important when so many plants are packed into a small area. “The White Garden’s soil had become very poor, so last year we removed every plant, and double dug the beds. We also added loads of organic matter and grit,” says Troy. A substantial herbaceous border requires a high level of maintenance. It needs planting, staking, watering, dead-heading, pruning, plant dividing, mulching and weeding. This decreases with maturity as plants merge together, covering the soil and smothering all but the most stubborn weeds. Regular hoeing starts in spring in the White Garden, reducing as the ground cover plants take over. “Every week, we spend a day cutting back and staking,” says Troy. “We keep to a minimum, preferring to partner plants that support each other. If a plant group needs bulking up, it is lifted and divided in early September and planted in the nursery. They will be planted out in spring.” Roses are fed in early spring and July to keep them in pristine condition. The gardeners at Sissinghurst use a homemade mixture of sulphate of potash with the mineral kieserite, in a 2:1 ratio. Old roses are prone to blackspot and rust, and need spraying fortnightly. “We mix seaweed feed, soapy solution and fungicide, applying with a leaf blower that contains the spray,” he adds.

Filling the gaps

Annuals are useful for filling any holes that appear. Cosmos is invaluable, with the variety ‘Purity’ bearing large open flowers in purest white, above delicate foliage. Taller snapdragons such as antirrhinum ‘Snowflake’, are another staple. Foxgloves are grown as biennials at Sissinghurst. Sown in the summer, they are planted out in autumn ready to flower next year. Throughout the garden are white perennial violas. These are the older variety Viola cornuta Alba Group which Troy finds more robust and resilient than newer varieties. In packed borders, this viola not only creates a pretty edging plant, but also flowers twice with a first flush in early summer. “After flowering we cut it down to ground level, propagating from the cuttings, while the plant flowers for a second time in August,” explains Troy.

Place for shrubs

Flowering shrubs pad out planting but need to be kept in trim and not allowed to outgrow their allotted space. These include philadelphus, hibiscus and various hydrangeas. There are delicate and sparsely flowered lacecaps and varieties such as ‘Annabelle’ with very large, spherical heads. Vita planted several cistus, common gum cistus, ‘Blanche’ and rock rose, which, over a long period, produce pristine white flowers that die gracefully.