If your containers (glass jars) aren't opaque it's better to paint them (using a base coat of chalk paint then coat of darker acrylic) than using aluminum foil which is more useful for other purposes.
I wouldn't have expected this article here but I'm glad it is! With our current food prices soaring and availability declining I'll start doing this. We already vegetable garden so this will be a good addition. The pump issue always kept me away.
Thanks.