Disabled children may like to potter about in the garden. Growing plants is something they may get a lot of satisfaction out of and all they need is a little help. First, make sure the bed is raised so that there is minimal bending. It should also be narrow, unless both sides can be accessed easily. Children's arms are shorter than adults, so make sure they can reach across easily. The total width should not exceed double the child's reach, or a single arm length for a border.
If it is too difficult to make a raised bed, a line or group of pots standing on bricks or a bench seat should be about the right height. If using a table, the pot should be shallow, or the top of it is likely to be too high for comfort. Safety is paramount, so if using potting mix, make sure they have gardening gloves that fit well.
Small tools will delight the user and if they have handles that are ergonomic, all the better, especially if the disability affects the hands. A small watering can be used to make the job of watering easier and if the pots are outside, a plastic chair placed strategically will be appreciated.
For wheelchair access it's a good idea to make the garden bed - Or place the pots - Close to a paved path. A gravel path is hard to wheel through, so should be avoided. It's important to choose plants that are not prickly or thorny to avoid unnecessary injury.