High Tech in the Green of The Hague

The Hague, the city known for its beautiful dunes, is also famous for its stunning parks and estates. The streets, avenues, and natural areas in The Hague are green thanks to its trees and plants. Nature in the city is vulnerable. The municipality does various things to protect, care for, and maintain nature in the city. Not only do trees and plants receive regular pruning, but they are also regularly watered. Especially new plantings are well taken care of because a city with diverse plants and animals is a healthy and attractive city. Read how the municipality protects and strengthens nature in The Hague’s city center with smart sensors and an online dashboard.

Author: Malon Gerrits

A city full of color

In addition to the greenery of different trees, many flower pots add a cheerful mix of colors to the city. From petunia-like plants and geraniums to white carnations, Indian reed, and much more. You can find them in various pots distributed throughout the city. These pots provide a solution to the space shortage in the city center. Each season, you’ll find different flowers and plants there, making the city center look beautifully vibrant all year round.

Dealing with drought (and downpours)

The trees and plants are well maintained and cared for throughout the year. Fixed routes help the caretakers provide water to the flowers, trees, and plants. Especially during the heat, these green water consumers appreciate an extra sip. However, water shortages and different heat plans make it more challenging. This needs to change, become smarter, and more efficient. Marco van Tol, Coordinator of the Green Center, also thinks so. Endless rounds with water tanks, not knowing whether the trees and plants are too dry or too wet, and simply watering because it’s the “task” for the day are a thing of the past. Soil moisture sensors from ConnectedGreen allow for smarter and more efficient work. But above all, it’s more sustainable!

More peace, more time, and at the same time, lower costs

About four years ago, Marco started monitoring soil moisture with wireless sensors. A pilot with ten sensors quickly yielded a lot of interesting data. The pilot was so successful that the soil moisture sensors became indispensable in The Hague’s green management just one year later. All flower pots in the city center are equipped with at least one sensor per location. In places with multiple flower pots, soil moisture is monitored using two sensors: one in a pot in the shade and the other in a pot in the sun. This way, Marco creates a reference point for action.

More time

By responding to the data, as a green manager, you can save a tremendous amount of time and water. For example, the flower pots in the sun can be watered while the pots in the shade can be skipped in a round.

“By better scheduling the routes based on this data, we were able to save two days per round quite quickly.” – Marco van Tol, Coordinator of the Green Center

“Three years ago, we started monitoring the flower pots in the city center. In the first year, it already saved us two days per round compared to previous years. When you calculate this in terms of labor, it’s a significant savings. It also meant that we could include more flower pots in one route.”

“We received more and more requests for flower pots, and at some point, you reach a limit with your planning and such, and you start searching in the margins. The sensors have really contributed to this. We were able to organize routes more efficiently.”

Less water

“When the gardeners start their routes, they check the app. If a flower pot outside the regular round urgently needs water, it can easily be included in the route. Because when the flower pots in the regular rounds still have 40% water, they require less water than before. Previously, we used to give each flower pot around 80 to 100 liters of water. The tank releases 7 liters of water per minute. So every liter of water you don’t have to spend on such a flower pot saves a significant amount of time.”

Apart from saving a lot of time, monitoring also saves a lot of water. “Take a period like the past month, when it’s very hot and dry. Previously, the gardeners used to think that all flower pots needed water in such heat. Now, with the sensors, the gardeners can see exactly where they need to water and where they don’t. This gives the gardeners much more peace of mind.”

More peace of mind

“Our drivers log into the ConnectedGreen app and see exactly how things are going on their route. Thanks to this monitoring, work can be done more efficiently, and more work can be accomplished in the same amount of time. Nonetheless, the boys and girls in the field feel more relaxed, creating a sense of calm within the team. Additionally, we avoid surprises, such as a sudden failure of an entire planting location.”

Increased satisfaction

“Monitoring puts you in a process that keeps getting better and better. In addition to more efficient route planning, the flower pots started looking better and more well-maintained. The rounds could be done more frequently, which also meant less failure. Ultimately, this resulted in fewer complaints from citizens, so they are satisfied.”

“Nationally, there is still a lot of surface water that can be saved through monitoring.” – Marco van Tol, Green Center Coordinator

Currently, Marco’s department is working with a total of 85 sensors. He is so enthusiastic that he recommends the sensors to other nurseries as well. He believes there is still a lot to save in terms of water supply for them. Even if the top layer seems dry, it could very well be moist underneath. You can only be sure of that by measuring it. Additionally, water pumps often run on diesel. So when you give less water, less fuel is needed. It’s a win-win situation.

New developments

In addition to technological advancements, the flower pots in The Hague are also undergoing significant developments. The polyester pots with small reservoirs are being replaced by flower pots made of recycled plastic. These pots have a double wall, which creates stagnant air inside, resulting in a constant soil temperature and less evaporation. The reservoir with overflow provides a good buffer. This makes the flower pots much more sustainable, and this can also be proven with the sensors.

“With the sensors, we can effectively measure the differences in flower pot types. In the first year, it turned out that the new flower pots needed significantly less water than the polyester ones. It’s possible that this is partly due to the choice of plants, which is why I’m reevaluating this year as well. However, this time I’m testing with different crops to see the difference compared to a polyester flower pot. So, the sensors serve multiple purposes within the Haagse Groen.”