Gardeners at the Knightshayes estate in Devon decided to grow loofah plants in order to supply the kitchen with zero-waste cleaning utensils.
While some sponges come from the sea, loofahs are grown from the Luffa cylindrica, a vine in the cucumber family.
These are, the National Trust has said, very easy to grow and suitable for any garden, and are "the same as growing courgettes".
They also do not litter the planet with waste like a throwaway plastic foam sponge.
Staff and volunteers are now using their home-grown sponges to wash their mugs and other dishes and say it is working very well.
The team grew 30 fruit which, once cut into segments, produced around 50 washing up sponges. Sponges not needed by the team will be sold in the onsite shop.
The team plan to grow more loofahs this year and are hoping for a sunny, warm growing season which will help produce the very fibrous sponges suitable for bathroom use.
Kitchen Garden Supervisor at Knightshayes, Bev Todd, said: “We know people are looking for ways they can live more sustainably. We hope what we are doing at Knightshayes will inspire others to think about creative, simple ways they can reduce their everyday impact on the environment.”
"You need to grow them up some kind of supporting structure, but there’s nothing more complicated than that involved. You simply grow them as you would grow courgettes.”
The National Trust has plans to almost completely eliminate single-use plastics from its sites by 2022.
In the last few years, the organisation has have replaced all disposable hot food and drink packaging with compostable products. There are also plans to remove single-use plastic drinks bottles, eliminate plastic packaging from shops and take as much plastic as possible out of the day-to-day operations. The latter includes finding alternatives for a diverse range of products from name badges and stationary to tree guards and plant pots.
Ms Todd added: "We have 80 volunteers and nine staff in our outdoor team, so that’s a lot of washing up and a lot of sponges. With the growing awareness of single use plastics, and their impact on the environment, we wanted to find a more sustainable alternative to the disposable plastic-based sponges we had been using."