In April, Jim Cable suggests shopping for yellow-accented plants, mulching beds, harvesting rainwater and making water available to garden wildlife
New growth abounds in the April garden, colouring in the winter gaps. For me it is the acid greens that are most in tune with the freshness and optimism of the season typified by the flower bracts of Euphorbia amygdaloides var. robbiae. The unfurling leaves of deciduous subjects are youthfully blond, and plant breeders have selected to enhance and extend this trait. Shrubs such as Physocarpus opulifolius ‘Aurea’, Spiraea x bumalda ‘Goldflame’ and Spiraea japonica ‘Golden Princess’ sport bright new foliage that darkens only slowly and never becomes dull.
If your garden needs a splash of highlighter-yellow, then you have a good excuse to visit a nursery or garden centre. Now is a good time to plant shrubs, providing you ensure they stay moist at the roots as spring turns into summer. This is one instance when a mulch can help. Covering the soil in a metre wide circle around the crown will reduce evaporation from the ground while the plant establishes and its roots extend.
Mulching a bed always takes me back to when I was training at the Royal Botanic Gardens, Kew, and caring for its philadelphus collection. The placement started at this time of year and is bookended, in my mind, by the forest-floor smell of Kew’s steaming compost at one end and the fruity notes of the first mock orange blooms at the other. It was satisfying physical work forking trailer load after trailer load and spreading it out evenly until it lay 10cm deep around the precious cultivars. I was taught not to pile it up against the woody stems to allow the bark to breathe. As well as helping seal in the winter’s rain, mulching can dramatically reduce the need for weeding. Kew’s compost is made in huge compost bays from plant material brought in across the 300 acres. It is turned by dumper trucks, which keeps it oxygenated, and the biological activity within it heats it to a point where any seeds within it lose their viability.
The outdoor scientific collections at Kew need to be maintained as monocultures of a particular genus, its species, forms and hybrid
