It’s a sad summer when you don’t have garden space to grow fresh tomatoes. Sometimes it’s because trees shade most of a root-clogged yard. Or perhaps you’ve moved to a condo or apartment building.
Take heart. You can grow veggies in pots, and get good results if you follow a few basic guidelines.
First, most vegetables need at least six daily hours of direct sun to thrive. Eight or more is better for tomatoes and peppers. West, south or southeast exposure is best. If you get less sun than that, you may still be able to grow leafy vegetables like lettuce and kale.
Next, for plants like tomatoes, get the biggest pot you can handle. I consider a roughly seven-gallon pot — about 14 inches across — the smallest decent size, and most tomatoes want a pot bigger than that.
Third, plant only in fresh potting mix. Soil from your garden or yard isn’t good enough for these plants, which in their restricted growing space need all the nutrients they can get from decent soil.
Finally, be prepared to water often, to fertilize occasionally and find a plant sitter if you go to the lake on a 90-degree weekend. In July and August or even on a warm, windy May or June day, plants in pots will quickly dehydrate and could wither beyond rescue by the time you get home unless someone is around to give them a drink.
Probably the most popular veggie to grow in containers in Minnesota is the tomato. Even if it’s warm in early May, hold off on planting tomatoes until mid- to late May, when the risk of frost is past. Tomatoes hate cold soil and can even rot if planted too early.
Some tomato varieties, with “patio” or “bush” in their name, were bred specifically for pot culture. They tend to be smaller plants that slow their growth once they reach a certain height.
Tomatoes have extensive root systems and like a roomy pot. My own preference is to find a pot at least 18 inches across (about 15 gallons). Make sure your pot has drainage holes, and if you’re a condo dweller with a neighbor who has a balcony below make sure to put a tray underneath to catch excess water! Plastic pots are lighter than terra cotta and will retain water better. Large pots will be heavy; if the sun shifts around your deck or balcony during the day, put the pot on a wheeled trolley that allows you to move it where the sun is. Tomatoes will take as much sun as you can give them.
Tomatoes should be planted deep. Gently snap off the lowest pair of leaves or branches on the plant, and bury the stem at least that deep — new roots will emerge there. All tomatoes will need a stake, tomato cage or other support to prevent branches from breaking once fruit appears.
Heirloom varieties like Brandywine and Mortgage Lifter get huge and are poor candidates for pot culture unless your container is really big. These plants can reach 5 or 6 feet by fall, and most pots simply aren’t big enough to allow them to thrive.
Plant breeders have also developed tomatoes that grow in hanging baskets or grow bags. Watering is an issue here, too, so these plants need constant attention. With tomatoes’ hunger for space, it’s safer to choose a big pot.
Many potting mixes already contain fertilizer, but continual watering will gradually wash fertilizer away. For heavy feeders like tomatoes, add a bit of slow-release fertilizer at planting or, once the plants are beginning to grow and looking sturdy, fertilize weakly every few weeks with a fertilizer that on the label shows numbers like 5-10-10. The middle number, for phosphorus, is the nutrient that encourages flowering and fruit. The first number represents nitrogen and spurs mostly green growth. For fruiting veggies like tomatoes and peppers, that first number should never be bigger than the last two numbers. Don’t let your enthusiasm for feeding the plant run away with you. Fertilizing less is always better than burning the plant with too much food.
Others to try
Peppers are another sun-loving veggie for containers. Though the plants look tiny at the store, give them ample spacing in a big pot or put them in smaller individual pots. Remember, they may need to be watered daily if it is hot.
Bush cucumbers and beans can be grown in large pots. Put several plants or seeds in a pot. The plants want something to climb on, so a small trellis, poles with wire or string strung between them or a teepee of poles, tied at the top, will give them the support they want. Beans, cucumbers, carrots, beets, radishes and greens like arugula and spinach can be direct-seeded in containers. Make sure to thin root crops to make sure the veggies have enough room to grow.
If your growing space is short on sunlight, consider leafy crops like kale, lettuce, spinach and mustard greens, all of which can tolerate as little as three hours of daily sun. Root crops need at least five hours of sun, but do better with more light.
Lastly, more people are experimenting with growing potatoes in wire towers, pots or even five-gallon buckets. Potatoes like a big container — a trash can or a big tub with drainage holes will work. It’s best to start with certified seed potatoes from a nursery, which are less likely to carry disease, and to choose varieties that mature early.
In containers, potatoes are planted in a few inches of soil, then soil is added as the plants grow. Here’s a page on growing potatoes in containers that illustrates how this works: how-to-grow-potatoes.co.uk/growing-potatoes-in-containers/how-to-grow-potatoes-in-containers/.
When harvest time comes, you don’t have to worry about spearing that spud with a pitchfork or shovel. Just turn the container over, and out tumble the taters. What could be easier, or more fun?
Mary Jane Smetanka is a Master Gardener and Minneapolis freelance writer.