Requirements for gardens and the planting of trees must be included in Labour’s planned new rules for housebuilders, green groups have said. The government is drawing up its future homes standard for new developments and it is not yet clear what requirements there will be for green space. Developers are currently subject to biodiversity net gain rules that mean they have to ensure there are more spaces for nature after a development is built than before construction commenced. Gardening groups including the Royal Horticultural Society (RHS) are now asking for rights to green spaces to be enshrined in the plans to boost housebuilding. Prof Alistair Griffiths, the RHS director of science, pointed to a study based on UK Biobank data that showed people with gardens tend to have lower mortality risks, lead healthier lives and be less stressed. “If you have more green space or a garden, you will do more physical exercise and be more likely to meet NHS guidelines for physical exercise. One of the greatest challenges the government faces in terms of the health service is levels of obesity, so this is significant,” he said. Clare Matterson, the RHS director general, said that including gardens with the 1.5m homes that the government has pledged to build could save the NHS money. “Let’s completely flip back around and make sure the outside space is actually thought about as much as the inside space. It has so many benefits, cost-saving benefits, particularly to the NHS,” she said. She added that homes on the market should have a garden performance certificate, like they have for insulation, to indicate the quality of the soil, the amount of water it stores, and the biodiversity. “When you buy a house you get an energy performance certificate, you have ratings for all the white goods in the kitchen. How about having a garden performance certificate? “Let’s allow people to make some really important choices and give an incentive for people who are selling homes to create really good gardens.” Developers often plan to include gardens and green space but overspend on the construction of the homes and put concrete where plants should be. Wayne Grills, the chief executive of the British Association of Landscape Industries, urged Labour to include gardens in its plans. “We can actually be in there advising the contractors that are there at the same time that construction is going on, rather than being allowed to come back and dig up that same piece of environment,” he said. “And the second thing for me [is] making sure that the budget is there. So we certainly see some really good, specified schemes, but very often the building is overspent over time and then landscaping that goes around it is cut back in many cases.” Griffiths said that in the medium-term future, the UK would have a climate much like that of Barcelona now, and would need more planting. “If you look at car parks and if you look at housing estates and developments in this country, there are no trees and there is no shade. This is not the case in France, Barcelona [north-eastern Spain] and other countries, they have spaces designed for urban cooling,” he said. A spokesperson for the Ministry of Housing, Communities and Local Government said: “The government recognises the importance of building high-quality housing, and our planning reforms set clear expectations to ensure new developments meet the standards required. “This includes taking into account the national model design code, which makes clear that open spaces, including private outdoor spaces, contribute to the quality of a place and to people’s quality of life.”