Planter Boxes: 10 Tips for Growing Tomatoes

1. Choosing the Right Planter Box

The first step toward a successful tomato harvest is selecting the perfect tomato planter box. The material of your planter box is essential.

Wooden boxes are durable and have a natural look, but they can rot over time if not adequately treated. Moreover, some include treatments that can leach into your soil, impacting your plants.

Plastic planters are lightweight and easy to move, but they might not last as long in direct sunlight. So, to eliminate that concern, choose one that's UV-resistant.

Metal planters look sleek but can bake your plants on a hot day in full sun. That stresses your plants and means you'll likely have to water twice daily.

Bigger is Better with a Tomato Planter

How deep should your planter be? Tomatoes need deep roots to grow strong and healthy plants, so choose a box at least 12-18 inches deep. The width should be wide enough to accommodate the plant without crowding its roots.

Drainage is another critical factor. Whatever gardening container you select must have drainage holes in the bottom. If not, drill several holes to prevent water from pooling. Otherwise, you risk root rot, which can kill your plants.

2. Selecting the Right Tomato Varieties

Tomatoes come in two main types of plants: determinate and indeterminate.

Determinate varieties grow to a specific size, produce fruit, and stop growing. Also known as bush tomatoes, these are perfect for planter boxes because they stay compact.

Indeterminate varieties, on the other hand, keep growing and producing fruit throughout the season. This requires more space and support, as some varieties can reach up to 20 feet tall.

You'll also want to consider whether you prefer heirloom or hybrid varieties. Heirloom tomatoes have rich flavor and diversity but can be less disease-resistant.

Hybrids typically resist common tomato problems and might be a better choice for beginners.

Finally, think about the local climate in your home garden. If you live in a cooler area, look for quickly maturing varieties. In warmer climates, choose heat-tolerant varieties that can withstand intense sunlight.

3. Preparing the Soil in Your Planting Box

The right potting mix for containers is crucial for growing healthy tomatoes. A good blend usually includes garden soil, compost, perlite, or vermiculite to ensure proper aeration and drainage. You can buy a pre-made mix designed for container gardening or combine these elements to make your own.

Tomatoes are heavy feeders, requiring many nutrients to grow well and produce a bountiful harvest. Regular feeding is essential to keep your tomato plants healthy and productive throughout the growing season. Without enough nutrients, your plants might produce fewer fruits, which may be smaller or less flavorful.

Consequently, don't skimp on soil amendments during planting. Use lots of organic materials like compost and manure. Adding a slow-release fertilizer at the end is also an intelligent choice.

4. Planting Techniques

When potting plants, you can start from seeds or seedlings. Starting from seeds gives you more variety of choices, but it takes longer and requires more attention. Small plants are a quicker way to start and are often more resilient.

Tomato plants need space to grow, even in planter boxes. Plant each tomato at least 18-24 inches apart to give them enough room to spread out. Planting them too close together can lead to competition for nutrients and water, stunting growth.

Equally important when planting, bury the tomato seedlings deeper than they were in their original pots. Tomatoes can grow roots along their stems, so planting them deeper helps establish a more robust root system. Snip off leaves several inches up the plant to ensure good depth.

After planting, you'll also need to consider supporting your plants. Staking, caging, or using a trellis are all effective methods. They'll keep your tomatoes upright and prevent them from sprawling excessively.

5. Watering and Mulching

Watering is one of the most critical aspects of growing tomatoes in planter boxes. Tomatoes need consistent moisture, but avoid waterlogging the soil in your planter box.

Water your plants deeply and regularly, especially during dry spells. Inconsistent watering can lead to problems like blossom end rot or splitting tomatoes.

Self-watering planter boxes are a fantastic solution for maintaining the proper moisture level. These planters have a built-in reservoir at the bottom that stores water. As plants grow, they can draw moisture as needed through capillary action.

As a result, your tomatoes get a steady water supply without the risk of overwatering or drying out. That makes it easier to keep your plants healthy, especially during hot weather or busy schedules.

Self-Watering Planter Boxes are a Plus

Self-watering planters are a green thumb’s best friend. They reduce watering frequency. That can be particularly beneficial if you live in an area with water restrictions or want to conserve water. Self-watering planters keep the soil moist, which helps stop problems like blossom end rot and fruit cracking. So, you'll enjoy a more abundant and healthy tomato harvest.

Mulching is another excellent way to retain moisture in the soil and reduce watering frequency. Spread a layer of mulch, such as straw, grass clippings, or wood chips, around the base of your plants. This helps with moisture retention, stabilizes soil temperature, and prevents weeds.

Consider adding a drip irrigation system using traditional planters to maintain consistent moisture levels.

6. Feed Your Tomato Plants Regularly

As mentioned, tomatoes are hungry feeders, so fertilizing is critical to produce a sizeable crop. You have several options:

• Balanced Fertilizers: Start with a balanced fertilizer, such as a 7-7-7, 10-10-10, or 14-14-14 (N-P-K) formula. It provides equal amounts of nitrogen (N), phosphorus (P), and potassium (K). A balanced blend helps plant growth, root development, and fruit production.
• Tomato-Specific Fertilizers: Tomato-focused fertilizers often have a higher potassium (K) content to support fruiting. A standard ratio of 5-10-10 or 4-6-8 provides more phosphorus and potassium to promote blooming and fruit development.
• Organic Fertilizer: Compost, well-rotted manure, fish emulsion, or bone meal can be excellent nutrient sources for organic gardeners. Organic fertilizers release nutrients more slowly than synthetic ones, providing a steady food supply to your plants over time.

When and How to Apply Fertilizer

Remember to add a slow-release fertilizer to the soil when planting. This will give your tomato plants a good start and provide essential nutrients.

During the initial growth phase, use a balanced fertilizer every 4-6 weeks to support leaf and root development.

Once your tomatoes flower, switch to a fertilizer higher in phosphorus and potassium. These nutrients encourage more flowers and fruits. Continue feeding every 2-3 weeks with a liquid fertilizer or according to the product's instructions.

Applying Fertilizer to Your Tomato Planters

For granular fertilizers, use them around the base of the plants. Gently work them into the top layer of soil, careful not to disturb the roots. Water the plants thoroughly after application to help dissolve the fertilizer and allow the nutrients to reach the roots.

For liquid fertilizers, mix according to the package instructions. Then, apply directly to the soil or as a foliar spray during regular watering. Spraying fish emulsion to your plants is also an excellent way to provide a boost.

Consistent feeding ensures that your tomato plants can access the nutrients they need to thrive. It helps ensure a generous yield of delicious, juicy tomatoes. Watch your plants for signs of nutrient deficiencies, such as yellowing leaves or poor fruit development. Adjust your feeding schedule or fertilizer type as needed.

7. Managing Pests and Diseases with Container Gardening

Even in planter boxes, tomatoes are vulnerable to pests and diseases. Common pests include aphids, hornworms, and whiteflies. You can manage them by regularly inspecting your plants and using organic pesticides. Sometimes, simply spraying your plants with water can dislodge pests like aphids.

Diseases like blight and root rot can also affect tomatoes in planter boxes. To prevent these, avoid overhead watering, which can create the damp conditions that diseases love. Instead, water the soil directly at the base of the plant. Rotating your crops yearly and cleaning your planter boxes at the end of the season can also help prevent disease buildup.

Many natural solutions can help deter pests and diseases if you prefer organic gardening. Neem oil, insecticidal soaps, and companion planting with herbs like basil can keep your tomatoes healthy without harsh chemicals.

8. Harvesting Tips for Your Tomatoes

Harvesting tomatoes at the right time is critical to enjoying their full flavor. Tomatoes are ready to pick when fully colored and slightly soft to the touch. If unsure, you can also judge by the smell—a ripe tomato will have a rich, sweet aroma.

When picking tomatoes, gently twisting to avoid damaging the plant. If the tomatoes don't come off quickly, use garden scissors or pruners to snip them from the vine. After harvesting, store your tomatoes at room temperature, away from direct sunlight, to allow them to ripen fully.

9. Troubleshooting Common Issues with Your Tomato Garden

Even with the best care, you might encounter common issues when growing tomatoes in planting boxes. Blossom end rot, for example, is a condition where the bottom of the tomato turns black and hollow. This condition often stems from calcium deficiency or inconsistent watering. To prevent it, ensure your plants are well-watered and consider adding calcium to the soil if needed.

Tomatoes can also crack from irregular watering, especially after heavy rain following a dry spell. To prevent cracking, try to keep the soil consistently moist.

Yellow leaves can indicate several issues, including nutrient deficiencies or overwatering. If you notice yellowing, check the soil moisture and consider adding a balanced fertilizer to boost your plants' nutrients.

10. Consider a Tomato Planter Kit

Tomato planter kits are an excellent choice for growing tomatoes in planter boxes. These kits typically include everything you need to start, making it especially easy for novice gardeners. Planter kits from EarthBox, for example, include:

• Self-watering planter box
• A staking/trellis system with wire ties
• Casters/wheels to move it around
• Mulch covers to prevent weeds and conserve water and nutrients
• Water fill tube to easily add water
• Aeration screen to prevent root rot and mold
• 7-7-7 fertilizer and natural dolomite
• Tomato & Veggie Boost (calcium nitrate supplement)
• Organic potting mix

A tomato planter kit can remove the guesswork of setting up your planter box. That allows you to focus on caring for your plants and enjoying growing your tomatoes. EarthBox’s tomato planter kit bundle costs as little as $118.99. You can re-use the kit year after year growing upwards of 20 lbs. of tomatoes each growing season.

EarthBox is the #1 Solution for Growing Tomatoes

Growing tomatoes in planter boxes is a fun and rewarding experience, whether you're a seasoned gardener or just starting. To ensure your success, EarthBox is an industry-leading solution. Its tomato planting system and grow boxes are lab-tested for performance.

Give it a try, and don't hesitate to experiment with different varieties and methods to find what works best for you. Happy gardening!