If these are the same as Morrisons 99p for 10 (about 12 litres volume), then I find them ideal for tomato plants.They have done 3 seasons , well ,nearly and will be replaced. You need to provide drainage holes , the plastic (polypropylene recycled I think) is very brittle and is best pierced with a red hot awl which causes reinforced holes rather than splitting if you try to drill . Have a wet rag to hand to douse any fires, taking care not to touch the molten plastic, it will burn and stick to your skin -ouch!
