Container gardening has its advantages. It’s perfect if, like me, you’re renting and want to be able to take your plants with you when you move. It’s also a great way to get around gopher problems and plots with poor soil or disease issues. Container gardening might be the only way to have a garden for many apartment dwellers, and vegetables and herbs provide a nice alternative to the standard ornamental container plants on a patio or deck. Because, yeah, you get to eat them! This type of gardening does, however, come with a whole new set of challenges and issues when compared to growing in the ground or a raised bed.
To grow a tomato in a pot is challenging because they rely on you for everything they need: you have to put the correct nutrients in the pot when you plant and also continuously feed them throughout the growing season.
First of all, you’re going to need a big pot. Tomatoes like lots of room to expand their roots. I used 15 gallon nursery pots because it was the biggest size I could find. The 20 gallon fabric pots (like SmartPots) are ideal because they let the roots breathe and air prune rather than becoming root bound. You need a separate pot for every tomato. If you’re reusing old pots, you should disinfect them first with a 1:10 solution of bleach water.
The second thing you’ll need is a good organic potting soil: 1.5 to 2 cubic feet per pot, depending on size. Don’t reuse old soil, tomatoes are very prone to disease and anything in old garden soil can infect them – that is actually another advantage of growing in a pot – you have a sterile medium! If your soil doesn’t have a wetting agent, it’s beneficial to moisten it first. This will prevent your soil from being hydrophobic when you go to water and ensure that the root ball gets wet. Now you can start out by putting around 4″ of soil into each pot.
The third thing you need is your amendments. Even though your organic potting soil has nutrients in it, tomatoes will need a lot more than that to get big and tasty, especially in a pot. You’ll need a couple handfuls of fish bone meal or bone meal for extra phosphorus, a few crushed eggshells for calcium, a handful of worm castings and a couple handfuls of a dry organic tomato and vegetable fertilizer. Some people also swear by adding a couple aspirin tablets for disease prevention (I didn’t have any).
Then, after your amendments, add a bit more potting soil. Place your tomato transplant in the container. I like to prune the lower leaves off of mine and bury them at least halfway. Pruning the lower leaves helps to prevent disease. Fill the container all the way to the top with potting soil, resisting the urge press down because that will compact the soil – watering will do that for you. I’m growing indeterminate heirlooms, so I also pinched the axillary buds, keeping the growth of the plant to the main stem. Then, as the plant grows, I trellis upward by tying to a hook on the overhang of the roof above. You can also make your own cages about 6-7′ tall, but you need to have a way to stake them if you do so, to prevent your pots from tipping.
Now you can place your pots where you’d like (at least 6 hours of direct sunlight) and water your tomatoes in well. I like to water once and then wait about 10-15 minutes and water again to make sure the potting soil has become thoroughly saturated. After this initial watering, you’ll need to water from every few days to a week. Tomatoes do not like to be constantly wet. There is no exact number of days, you’ll need to stick your finger into the soil to see if it needs water. If you can feel moisture it’s fine, if it’s dry then water. When you water, do water slowly and deeply. As the weather heats up and your plant gets bigger, it will need water more often. If you’re using black plastic pots, place other plants or shade cloth in front of the south side of the pot to prevent the root ball from overheating.
Your tomatoes will use up all the yummy amendments in the pot after about a month, so you’ll need to fertilize once a week with a worm casting tea made with water and organic worm castings (or a good organic liquid fertilizer, diluted according to directions). You’ll need about 2 gallons per plant each week. In addition to this, you can foliar feed with the worm casting tea (you can add a crushed aspirin to this as well for disease prevention).
May the best tomato win!