Growing Tomatoes Indoors and Outdoors in Pots and Containers
Tomatoes are easily grown in pots, containers and hanging baskets, both indoors and outdoors. When grown indoors, tomatoes spend their entire vegetation period protected from strong winds, sudden drops of temperatures and rainstorms, and can provide gardener with steady supply of tomatoes year long. When grown outdoors, plants can spend some time indoors and when danger of late frosts is gone, pots and containers can be positioned on permanent outdoor locations, without stressing the plants with additional transplantation.
Updated: January 7, 2020.
Also, tomatoes can be rather decorative plants, with number of flowers and colorful yellow, red, green, orange etc. fruits.
When growing plants indoors, treat plants as if they are grown outside:
- Soil selection: soil should be slightly acidic (pH 6.0 - 6.7), well drained, well aerated, rich in nutrients. Tomatoes require moisture, but they don't like soggy soil. Best soil is good potting soil mixed with aged manure, humus and compost. If it 'feels too heavy', add some sand, but not much - sand helps drainage, but retains almost no nutrients. When last fruits are removed from plants, remove tomato plants and use soil for growing other vegetables/herbs/flowers - crop rotation is important both outdoors and indoors.
- Pots and containers selection: size and shape of growing pots and containers depend on growing area, grown varieties and personal preferences. For example, when grown on windowsill and using smaller varieties, pots with diameter of 15cm (6 inches) can be used. Rounded pots enable gardener to rotate pots slightly on regular basis leading to more even growth of plants. Depending on variety, as tomatoes grow, some form of support must be introduced - wooden or wire tomato cages can support the plants when required. Also, hanging baskets and upside-down planters can be very decorative in any garden or home and they don't require any additional support for plants.
- Lighting - positioning plants near windows benefit from using sun for lighting. However, tomatoes like sunny positions and growing them near windows often doesn't provide enough light and additional lights may be needed. When grown away from windows, tomatoes require artificial lighting for successful and healthy growth. For example, full daylight (not direct sun) can be around 10.000 - 25.000 lux, direct sunlight is between 32.000 - 130.000 lux (even 180.000 lux, depending on location and season). Obviously, tomato plants will benefits greatly from using artificial grow lights.
- Pollination - when grown outside, tomatoes are pollinated by vibrations and plants being shaken by wind, bees and other insects. To pollinate tomatoes indoors, shake gently plants and provide some source of light air flow around the plants during periods of flowering.
- Temperature - tomatoes grow best when temperatures are above 18°C (65°F). They can survive and even grow well on much higher temperatures (40°C, 105°F - often found in greenhouses with good insulation positioned on full sun). Optimal temperature for growing and flowering is around 25°C (77°F) and if possible, that temperature should be maintained indoors.
- Fertilization - tomatoes must be planted/sown in rich soil. Since amount of soil per plant can be limited, especially when compared with growing tomatoes in garden, fertilization of tomatoes in pots and containers is best done using liquid fertilizers on a weekly basis - just add required amount of liquid fertilizer into the water and water the plants. Also, using liquid fertilizers enables gardener to change ratios between main nutrients (NPK - nitrogen, phosphorous and potassium), depending on vegetation period of plants.
- Watering - tomatoes prefer moist soil, but waterlogged soil can damage the roots. Constant moisture is very important during fruiting season, since large fluctuations can cause damage to the fruits. Depending on the temperature in the room, position toward the sun, type of artificial lighting, water plants few times per week, or use small dripping system. If temperatures are above 30°C (86°F), water plants daily. Note: be sure that pots and containers have enough drainage holes. Self-watering pots and containers are good solution for avoiding issues with irregular watering. Keep in mind that tomatoes have large root ball and the larger the pot, the better.
- Suitable varieties - There are number of suitable tomato varieties that can be successfully grown in small pots/containers/baskets. Some of them are:
Sungold: small, orange-red, cherry type tomato, hybrid, nice sweet taste, plenty of fruits.
Stupice: tolerates cooler climate, taste could be better, but it is OK, compact plant with red fruits. Rippen early.
Black Krim: heirloom tomato suitable for containers, has large, purple-redish fruits.
Wapsipinicon Peach: heirloom tomato, yellow orange fruits with fuzzy skin (like a peach). Also, very ornamental plant with tasty fruits.
Brandywine: very popular variety. Strong and rather large plants, require good cage or several stakes per plant. Can be kept 'under control' with regular pruning. One of the best tasting tomato varieties.
Silvery Fir Tree: compact and ornamental plants, round red fruits with gray/silver green leaves.
Riesentraube: - grape type tomato, with 20-40 small tomatoes in clusters. Very tasty fruits, too. Early variety.
There are many other varieties that can be grown in pots, indoors or outdoors. In fact, if large enough pot is used, any variety can be grown.
- Sowing and Transplanting - when grown in pots, IMHO, tomatoes should be sown in pots directly, without transplanting them - sow 3-4 seeds in the pot, cover them with thin layer of soil and water gently. When they start to grow, remove all but the strongest plant. If there is room for more plants, sow 2-3 times more seeds than you need plants and remove weaker plants. If number of seeds is issue, sow single seed per small pot and when time comes, transplant the best plants in permanent containers. In order to prolong harvesting season, sow seeds of the same variety every 2-3 weeks.
- Pests and Diseases - if area is kept clean and soil is new, there should be no issues with pests and diseases. However, it is good practice to treat the plants with mild, water soluble fungicides, as precaution - note that some gardeners strongly disagree with such treatment, but ... When grown in pots, plants are usually very close to each other, and any disease can spread rapidly. Also, check your plants daily for pests and if possible, remove them manually. If required, chemistry can help, but best tomatoes are grown without various '-icides'. After all, strong and healthy plants can tolerate few bugs easily.
Long story short - growing tomatoes in pots is fun and easy and can provide long year supply of fresh tomatoes for entire family. Sungold and Brandywine tomatoes are recommended varieties for newbie indoor gardener, but don't limit yourself - feel free to test new varieties when have opportunity.