Harvest* self watering greenhouses are larger than a cold frame, but smaller than a traditional greenhouse. They collect rain water and store it in a built-in water tank / water butt. There’s an internet-connected control unit which pumps water into your Harvest greenhouse, with a choice of two separate watering zones for different plants.
The system tracks temperature and soil moisture too; so you can choose to water based on a simple timer, or a more complex method using environmental inputs.
The Harvest greenhouses are available in three sizes to fit anyone’s growing spaces.
*Actually Harvst, but lots of people mistype it, and Google suggests you’ve searched for Harvest greenhouses, so here’s a page to bring you to the right place.