Defra said: "You need to get a plant health certificate from the Animal and Plant Health Agency (APHA) to export plants and plant materials to most non-EU countries. You must send this with your consignment. Contact APHA for detailed information about the documents you need to export to your consignment.Defra added: "Some countries require that your consignment travels with an import permit as well as a plant health certificate. You should ask the recipient whether you need an import permit, and have them send it to you. Contact APHA for help in meeting the conditions it sets out."
For exporting previously imported material, you need a re-forwarding plant health certificate if you're exporting material which came into England or Wales from a non-EU country with a plant health certificate and was then stored, repacked, or split up.
Contact APHA to get a re-forwarding certificate - send them a copy of the original plant health certificate and they can tell you if the material must be inspected or tested.
You must have the following materials inspected by APHA at your site, to get a plant health certificate:
plants and plant products, bulbs, fruit and vegetables (including seed and ware potatoes),grain, farm machinery and seeds for sowing.