How Helsingborg picked Capillary Hydroponics for its high footfall Steam Ferry Park

The southern Swedish city of Helsingborg had a challenge before it. It was redeveloping a downtown space by the sea where the city’s residents could gather with friends and family, walk on the promenade, and attend events such as concerts. At the heart of this plan was the 1,300 sqm Ångfärjeparken or the Steam Ferry Park.

The city’s planners were keen that the park had natural grass but there were concerns that natural grass would not be practical for what was envisioned as a high-footfall area. Instead, they were being given options such as artificial grass.

But any non-natural surface would have been incompatible with Vision Helsingborg 2035, an ambitious plan where, among other things, the leaders of the city of 150,000 residents set themselves a target to achieve net zero greenhouse gas emissions by 2035 (10 years ahead of the net-zero date set by Sweden itself) and also stated that by then the city should “be a creative, vibrant, shared, global and balanced city for both people and businesses” as well as “exciting, attractive and sustainable”. In fact, in the years following the announcement of Vision 2035, Helsingborg was named Sweden’s most environmentally friendly municipality four times in a row and was also awarded second place in the European Capital of Innovation Awards 2020. 

So artificial grass did not seem to be an option.

The city got in touch with the Swedish Golf Federation hoping they could connect them with a “grass expert”, and the Federation put them in touch with Certified Golf Course Superintendent Martin Sternberg, founder and CEO of CapillaryFlow, and inventor of the Capillary Hydroponics turf system that is revolutionising the way grass is grown in sports fields, equestrian arenas and public spaces across the world.

“The city wanted real grass in the park,” said Sternberg. “They wanted that green feeling in the middle of the square. But everyone told them you can't have natural grass if you want to have concerts as people are just going to wreck it.”

After talking to Sternberg, the city decided to invest in the solution and CapillaryFlow set up a Capillary Hydroponics system in Ångfärjeparken in 2021. 

“It's challenging and exciting to test completely new technologies, but at the same time it is completely in line with the City of Helsingborg's values ‘dare, test and do’,” said Elisabeth Möllerström, landscape architect at the City planning and technical services department in Helsingborg. “This is how we evolve the city for the better.”

How it works

The Capillary Hydroponics system’s benefits are manifold but there are three major ones for a public park and high-footfall area such as Ångfärjeparken considering the maintenance costs involved. First, the system is self-watering. Two, it consumes up to 85% less water. Third, the system’s structure makes the grass very resistant to compaction when people walk or drive on it. 

Here's how it works. 

The system is comprised of several layers: an impermeable liner that sits on the soil, drainage pipes, drainage gravel, a layer of Capillary Material (a special pervious concrete that has an approximate porosity of 20%), washed sand and finally grass. 

The area under the surface is split into two equally large parts. A control basin filled with water is placed on the outside and has pipes that feed into the middle of each cavity. It automatically oxygenates and pumps water mixed with nutrients back and forth between the two sections several times a day, watering the roots as it goes. The level of the water table is completely controllable and the water moves between each cavity at a fully adjustable rate too. This system minimises the amount of water required and exposes the roots to oxygen frequently while expelling carbon dioxide, thus promoting strong root growth. 

Capillary Material ensures a perfectly flat and level base beneath the rootzone, which is crucial for the functioning of a hydroponic system.

The many layers the grass sits on in this system is one of the reasons why it is so resistant to compaction. Whenever normal grass grown on plain soil is driven over or subjected to heavy footfall, its roots get compacted and it begins to die. But the grass grown using Capillary Hydroponics sits on sand, not soil, and its roots are much stronger and deeper because of the hydroponic system that waters it. Additionally, the layer of Capillary Concrete moves any excess water down with the force of gravity for drainage, and up against the force of gravity to nourish the roots. 

“This is a totally different way of thinking of how to use grass,” said Sternberg. “So it takes time to convince people that it works. But when they come to Helsingborg, and they walk on it, or drive a bike, car or truck over it, they can't understand how it is soft on the top for the kids to play but it doesn't compact.”

A game changer

IIn the summer of 2022, a concert with almost 3,000 attendees was held at Ångfärjeparken. The lawn did not have any plastic cover protection and people stood on the grass for several hours two days in a row, yet there was no damage to it, said Sternberg.

“The beauty of our system is that it has more than twice the lifespan of natural grass, five times the lifespan of artificial grass and it is easier to maintain than artificial grass,” he added. “Everything is automatic. You don't really need to touch it much.”

Andréas Hall, development engineer at the City Planning and Technical Services Department in Helsingborg, highlighted the technical benefits of the system. “The technical advantages of this project are that those who take care of the grass get a very good control over the most important parameters that affect the grass throughout the year, from the temperature in the soil to the nutrients,” he said. “In terms of design, self-irrigation and measurement are neither seen nor heard, which contributes to a better visitor experience. In addition, no one risks getting wet feet from walking on the grass!”

Sternberg says the Capillary Hydroponic system is far more beneficial than any existing system. “It is so inexpensive and the benefits are so great in terms of carbon emission sequestration, pollution cleaning and water catchment to prevent flooding that cities cannot afford not to implement it,” he said. “It solves all these problems in cities and yet it costs less than artificial turf to put down.”