Tomatoes are the Holy Grail for many gardeners. Growing tomatoes in containers can be hugely satisfying or a flat out disaster. Sometimes there is nothing you can do to prevent tomato fail - bad weather, late blight or critter problems. However there are some things that you can do to improve your chances for tomato success.
1. Use Really Big Containers
One of the most important things you can do to ensure tomato success is to use a big enough container - the bigger the better. For one plant (unless it's a very small tomato variety), you need a pot or container that is at least a square foot - 2 square feet is better. Five gallon buckets (the ones you get at hardware stores, or for free at restaurants of food factories) are the perfect size for one plant. I use a large size reusable grocery bag and that's a perfect size too.
I'm a tomato fanatic and grow them primarily for food, not for looks, so I put one plant per container (unless it an Earthbox or an enormous container or raised bed). Lot of people suggest growing herbs and other plants in the pot too. Not me. It's hard enough to give tomatoes the consistent amount of moisture they need without throwing other plants that will compete for the water.Vegetables
2. Water, Water and More Water (But not too Much!)
The key to tomato success is to give your tomato plants a consistent amount of water, which can be the biggest challenge for growing tomatoes in pots. The goal it to keep the soil moist, not wet. Too much water and your plant's roots will rot. Too little water and your plants will get weak and your tomatoes will get blossom end rot.
Too little water and then too much water and you will have tomato disaster. The easiest way to deal with this is to use self-watering containers. Otherwise, you will have to check your tomatoes every day. I often find in the heat of the summer, or if it's hot and windy, I have to water twice a day.
If you have too much rain, protect your tomatoes by moving them into a sheltered area or cover them - if they are small enough.
Also, water in the morning (plants take up and use water more efficiently in the morning) and water the soil, not the plants.
Self watering containers and grow boxes work really well for tomatoes. For more info:
3. Feed Your Tomatoes
It is critical that you feed your tomatoes. Most potting soil (which is essential for growing almost anything in containers), has no nutrients in it (be sure to check on the bag to make sure it doesn't already have fertilizer mixed in). You will need to add a slow release fertilizer to your potting soil, making sure to mix it in throughout your container. I like both Bradfield Organics or Espoma, tomato specific fertilizers, but you can use any all-purpose, slow release fertilizer.
I then give my tomatoes a watering with a diluted liquid kelp meal and fish emulsion fertilizer every week or every other week, depending on my industriousness.
4. Give Tomatoes in Containers Sun - Lots
Most people way overestimate the amount of sun they get. So really figure out if your tomatoes are getting enough sun. 6+ hours full sun is the minimum and 8+ hours is better. Either use a sun calculator or go out and check your tomato containers several times over the day and time how much sun your tomatoes are getting. If they aren't getting enough sun, move them to somewhere they will.
Make sure to harden off your tomato seedlings - too much early exposure to wind and sun can weaken or kill your small plants.
Tomatoes also like heat, so don't put them outside before it gets really warm (nights 50 °F), or be ready to move or protect them from the cold.
5. Plant Tomatoes Deeply
Most plants wil not thrive if you plant them deeply, tomatoes are different. Roots will develop from stems that are under ground and your tomatoes will be stronger and healther. Dig a hole so that most of your plant is covered by soil, making sure that you remove all the leaves below the soil line. If your pot isn't deep enough to sink the tomato deeply, (though it should be if you followed item 1!) you can also lay the plant on it's side and bury it that way.
Tip 5. 5 Choose great tomato varieties. There are a lot of bad tomatoes out there - mealy and tasteless - even heirlooms, so make sure you are planting tomatoes you will love.