You can edit and update all aspects of your listing easily and as often as you like. Click the Edit produce link on the listing page or from your My Produce page:
Edit the fields in the same way that you add produce - see the step by step guide if you need help.
As a general rule, if the source of your produce (tree, bush, plant, hive ,etc) is still alive it is better to keep your listing published and change the status to growing rather than unpublishing. However there are certain times when removing your listing is a better choice, such as for annuals.
Visit your listing or My Produce page and click Unpublish to hide your listing from public view. Note that your listing won't be permanently deleted, but it will only be visible to you. This is useful in the case of annuals, where you might start growing them again next season. When you re-publish your listing you'll retain your subscribers rather than having to start from scratch.