How to Grow Tomatoes in Bags: Organic Gardening Simplified

Posted on Categories:"How To Grow", Edible Plant Growing Information
cherry tomato in grow bag by a rocking chair

Harnessing the Power of Portable Gardening: The Secret to Growing Tomatoes in Grow Bags

Tomato cultivation in grow bags has become increasingly popular among organic gardeners. This method combines the convenience of container gardening with the benefits of organic cultivation, offering a practical solution for growing tomatoes in limited spaces. This article explores the nuances of growing tomatoes in grow bags, focusing on organic practices from seed to harvest.

1. The Appeal of Tomato Grow Bags

Grow bags, typically made from breathable fabric, offer an ideal environment for tomato roots to thrive. They provide excellent drainage and air circulation, crucial for healthy tomato growth. The portability of grow bags also means they can be moved to optimize sunlight exposure throughout the growing season. Grow bags are lighter than other traditional containers i.e. clay pots. Lighter bags are easier to move during late frosts too! (cough, cough, Minnesota)

2. Choosing the Right Grow Bag

For tomatoes, a 7 to 10-gallon grow bag is usually sufficient. Use 7-gallon bags for cherry tomatoes. 10-gallon bags are a great choice for Romas and larger slicing tomatoes. This size accommodates the root system of a tomato plant while ensuring stability. The material of the bag should be durable, UV resistant, and breathable to facilitate healthy root growth and prevent overheating.

3. Selecting Tomato Varieties

When growing tomatoes in bags, both determinate (bush-type) and indeterminate (vining-type) varieties can be successful. Determinate varieties, like Tasmanian Chocolate, usually grow about 3-4 feet tall and are well-suited for bag cultivation. Indeterminate varieties, such as Sweetie and SunGold, can reach over 6 feet and will require staking or trellises.

4. Organic Soil and Fertilization

Use high-quality organic potting mix in your grow bags. The mix should be rich in compost and organic matter to provide the necessary nutrients. Supplement with organic fertilizers like fish emulsion or bone meal throughout the growing season to encourage robust growth and fruit production. Tomatoes require a lot of nutrients to thrive. Synthetic “slow release” fertilizers are a good choice too for ensuring your tomato plants get what they need throughout the season. Watch the plants as they start to size up. Discoloration of leaves is a good indication the plant is not getting all the nutrients it requires.

5. Planting and Germination

Start tomatoes from seeds indoors about 6-8 weeks before the last frost date. Transplant seedlings into grow bags once they have several true leaves and outdoor temperatures are consistently warm above 50F. Note: Tomatoes don’t grow below 50F and will only idle in place until the temperature threshold is passed. Typical germination to transplanting time is around 60-80 days, depending on the variety.

6. Watering and Moisture Management

Tomatoes in grow bags require regular watering as the soil can dry out quickly. Water deeply and consistently, ensuring the soil is moist but not waterlogged. Mulching the top of the grow bags with organic material can help retain moisture and regulate soil temperature. Power tip: automate the watering by using a timer and hose or placing the grow bag in a bucket/tray of water. Keep in mind the plant will wick water up from underneath!

7. Sunlight and Temperature

Tomatoes need at least 6-8 hours of sunlight daily for optimal growth. Grow bags can be easily moved to ensure adequate sun exposure. Ideal temperatures for tomato growth are between 55°F and 85°F. Protect plants from extreme heat by placing the bags in a location with afternoon shade. If you live in a northern climate, find a southern exposure area for your tomato grow bag.

8. Pruning and Support

Pruning is essential, especially for indeterminate varieties, to encourage air circulation and fruit production. Regularly remove suckers and lower leaves. We remove suckers up until the first fruit cluster. This keeps the grow bag soil surface less cluttered for watering. Provide support with stakes, cages, or trellises to keep the plants upright and prevent them from sprawling on the ground.

9. Organic Pest and Disease Control

Monitor plants regularly for signs of pests or diseases. Use organic pest control methods such as introducing beneficial insects, applying Neem oil, or using insecticidal soap. Neem oil can and copper-based fungicides are a good option for preventing problems..

10. Harvesting and Yield

Tomatoes are ready to harvest when they are firm and have achieved their full color. Most tomato varieties reach maturity and are ready for harvest about 60-90 days after transplanting. Regular harvesting encourages further fruit production. Note: If you live in a northern climate, you’ll find there may not be enough time for another round of fruit production before the first frost!


Growing tomatoes in grow bags is an excellent choice for organic gardeners, particularly those with limited space. This method offers flexibility, ease of care, and the joy of harvesting fresh, organic tomatoes from your own portable garden. With proper care, including suitable soil, regular watering, and pest management, your grow bags can yield a bountiful and delicious tomato crop, season after season.