Growing vegetables in tubs is a practical alternative if you have little gardening space. Attractive tubs fit on a deck, balcony or even the front steps. Tubs are also a good way to protect growing vegetables from slugs and other pests since the small spaces are easily managed. Use any tub that suits your space and has not been used for holding chemicals.
Choose your tubs taking into account the eventual size of your plants. Use large 10 gallon tubs for mixed plantings. Big plants like tomatoes need at least a 5 gallon container. Plant medium-sized root vegetables in a 2 gallon tub, single small vegetables like cucumbers in 1 gallon tubs.
Plant in wood containers like whiskey half barrels or use metal washtubs. Avoid damaging vegetable roots by painting the inside of metal tubs with asphalt as recommended by Florida IFAS Extension experts. Using plastic containers like laundry tubs means less watering, but make sure there is adequate drainage.
Find a location with 6 hours of direct sunlight a day to grow and ripen vegetables properly. According to Texas A&M experts, "Leafy crops such as lettuce, cabbage, greens, spinach and parsley can tolerate more shade than root crops such as radishes, beets, turnips and onions."
Drill or poke drainage holes in tubs if they have none. Use a drill with a 1/2 inch metal or wood bit for large tubs. Use a hammer and spike nail for small single plant tubs. Drill or punch 6 drainage holes spaced at least 1 inch apart in your container bottom or along the tub edge 1 inch above the bottom.
Purchase potting soil formulated for vegetable growing or mix your own soil. Use equal parts finished compost, sand and peat moss. Put 1 inch of gravel in the tub bottom for drainage. Mix a good time-release fertiliser into potting soil. Fill the tub with soil mix up to 3/4 full.
Check vegetable space requirements and choose vegetables that won't overgrow the tub. Use started transplants to get a jump on vegetable harvest.
Plant your transplants in your tub keeping them 1 inch away from the tub sides. Carefully fill around them with soil. Adjust their height so that the top of the root ball is at the surface of the potting soil when done.
Water thoroughly and make a watering schedule. Kathryn Hopkins of Maine Cooperative Extension advises "Plants in containers dry out more quickly than plants that are in the ground: you may have to water them daily."
Apply 20-20-20 water soluble fertiliser mixed according to manufacturer's directions every two weeks when you water if no timed release fertiliser was added to your soil mix.
Pick fruit as it ripens to increase the harvest. Overripe vegetables will go to seed and vegetable production will stop.
Make watering easy by installing drip irrigation with bubblers in your tubs and putting the system on a timer. Line your tubs with copper strips found in garden stores and nurseries to keep slugs and snails out. Keep vegetable growing information handy by stapling one of the nursery care tags for each type of vegetable onto a small stake. Push the stake with the tags (or labels) into the tub's soil for a quick care reference.
Know your vegetable spacing requirements and stick to them. Crowded vegetables can become stunted and fail to produce. Avoid potbound vegetables by using tubs with 6-8 inches of soil mix for leaf vegetables. Root crops and large vegetables like amaranth and tomatoes require at least 5 gallon tubs.