Between the lines: the creation of West Handyside Park, King’s Cross. Photograph: John Sturrock
We have just completed the planting of Handyside Gardens, a public park that is part of the redevelopment around the new Central Saint Martins in King’s Cross. It is a strip of land wedged between a modern building and the old train sheds. The site couldn’t be more urban: underneath it run the tube lines of the London underground.
The site was once an industrial hub and a terminus for the grain from the east and coal from the north. We drew from the previous network of railway tracks to provide us with linear paths and beds that helped to slide the park between the buildings. I also wanted it to suggest a place that was reminiscent of railway sidings, with a planting of garden escapees that to this day use the infrastructure of the industrial revolution for their own migratory purposes. Asters and shrubby willows feather their way through swathes of grasses to give the feeling that the planting has evolved in this newly created space.
As per usual with a site that is still in flux the planting dates got pushed back and the guys were working in the rain, with ever-shortening days. Despite the hold-up, this window between summer and winter is my favourite time of year to plant, because there is warmth still in the ground. If you tip a pot carefully upside down and give it a sharp tap on the rim to set the root ball free, you can see just how ready the roots are to escape and make their own way in the ground. Although plants may appear to be dying back for the winter, as soon as they come into contact with the soil they make their move towards independence.
All our plants were pot grown or containerised, as our original plant date was too early to use bare root or root-balled material. It was important that the perennials were checked over before planting. The roots should not be twisting their way out of the bottom of the pot, but there should be enough root growth to hold the soil together so that when you tip it out, the root ball stays firm enough to not be disturbed as it goes into the hole.
All our trees were grown in air pots – a modern system that uses pots with perforated sides so that as the roots hit a hole in the pot, and air, they terminate and branch to form a more fibrous root system. A good root system on a plant will mean it is able to draw upon minerals and water in the soil and establish itself quickly.
The soil in the park was all imported and it has been important to get it right. This goes for any new plant. A hole should be a third to twice the size of the rootball so that you can backfill with friable soil enriched with compost. Planting at this time of year requires little watering but pots that are dry should be plunged in water then drained before being planted. A handful of blood, fish and bone to every square meter and a top dressing of mulch will set a new planting up for the coming months so that, by spring, everything is ready for the off.
Containerised plants can be planted at any time of year, but remember that evergreens will need watering in winter, as they can dry out in cold and windy weather