These can be useful if the weather is poor or if large numbers of people turn up at once. Try to arrange small prizes for the winners. Ideas include:
Name a collection of herb plants and/or describe how they smell (fun if you can include some unusual mints such as 'Eau de Cologne' or apple).
Matching the above-ground and below-ground parts of vegetables (e.g. beetroot, carrot, celeriac, garlic, Jerusalem artichoke, onion, parsnip, potato, radish, turnip). Fun if you can have the actual vegetable, then a drawing or photo of the leaves.
Get families outside to familiarise themselves with the garden by answering questions or collecting objects.
One person is blindfolded and all the other people form a ring around that person. Two children are then selected to make their way from one side of the circle to the other as quietly as possible. They are not allowed to run and the person blindfolded must try to catch them using sound rather than sight.