Garden Expert Joe Swift Reveals Three Steps to Perfect Container Shrubs
A familiar face on BBC Gardeners' World and a regular at the RHS Chelsea Flower Show, garden designer Joe Swift has shared crucial advice for gardeners looking to maintain healthy container-grown shrubs. With spring in full swing, Swift emphasises that if you only "do one thing" this week, it should be repotting your shrubs to avoid them becoming "pot-bound."
Swift, who has been a presenter on BBC Gardeners' World since 1998, explains that while many shrubs thrive in containers, they require repotting every few years. Neglecting this task can lead to roots completely filling the pot, which prevents the plant from retaining moisture or nutrients, ultimately stunting healthy growth.
Step One: Consider Container Size
It might be tempting to place your shrubs in a much larger pot, thinking it will last for years, but Swift warns against this. If the soil is too loose, the plant could "rock in situ," creating air gaps that disrupt growth. This can also lead to issues with waterlogging or dryness. Instead, Swift recommends moving up just one size, specifically allowing 2.5cm to 5cm of space all the way around the root ball. To save on costs, he suggests tackling multiple plants at once and switching pots between them.
Step Two: Pay Attention to Drainage and Compost
Proper drainage and the right compost are vital for shrub health. Swift advises placing a 2.5cm layer of crocks over the drainage holes to prevent water buildup. He notes that general compost is too light for shrubs; they prefer a soil-based compost like John Innes No 3 or a homemade mix. To make your own, combine two parts good garden soil with one part sieved garden compost. Adding a little fertiliser, such as blood, fish and bone, mixed into the compost can boost nutrients. Once potted, ensure the shrub is sufficiently watered to settle the soil.
Step Three: Importance of Pruning
As shrubs grow, they may become too large to repot into bigger containers. To keep size under control, Swift recommends pruning both top and root growth. Remove the shrub from its pot and scrape away some compost to expose the roots. Prune back some of the roots, creating a 2.5cm to 5cm gap, and focus on removing weak or damaged roots while retaining fibrous feeding ones. Additionally, prune a bit of the top growth before repotting to balance the plant's structure and promote healthy development.
By following these three steps, gardeners can ensure their container-grown shrubs remain vibrant and robust, avoiding common pitfalls like pot-binding. Swift's expert guidance, drawn from decades of horticultural experience, provides a clear roadmap for maintaining beautiful and thriving garden containers throughout the seasons.
