While heirloom tomatoes have amazing flavor that makes the perfectly red and smooth hybrid varieties in the grocery store taste like plastic, they lack the disease resistance that has been bred into modern tomatoes. Even the best heirloom tomatoes rarely produce as long or as well as a hybrid strain because they succumb to disease at some time during the season. Fortunately, there are several things you can do to keep your best heirloom tomatoes healthy and vigorous.
Secrets for Growing the Healthiest, Best Heirloom Tomatoes:
1. Grow Grafted Heirloom Tomatoes
The best heirloom tomatoes to grow are grafted, just like fruit trees. This means that the heirloom stem is attached to the root stock of a vigorous, disease-resistant hybrid. The fruit will be all heirloom, but the root stock will reduce the occurrence of soil borne diseases. In addition, the stronger growth helps combat foliage diseases as well.
The University of North Carolina published a great resource on grafting for disease resistance in heirloom tomatoes.
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2. Use a High Tunnel for the Best Heirloom Tomatoes
All tomatoes hate having wet leaves. Even the best heirloom tomatoes can suffer from blight, leaf mold and other ailments if their foliage is damp. Using a high tunnel protects the plants from rain, allowing you to water at the roots only.
3. Prune Frequently
Pruning your best heirloom tomatoes improves air circulation allows sunlight to reach all the leaves of each plant, helping them resist disease. If you are using grafted heirloom tomatoes, try pruning them to have two, three or even four main branches. This allows for high yields with few plants, making the cost of grafting worthwhile.
4. Space Plants Properly
The best heirloom tomato seeds grow into large, vigorous, sprawling plants. Avoid crowding them. Wide spacing (at least one foot between plants and four between rows, or more!) will improve circulation and reduce the occurrence of disease.
5. Use Mulch for Growing Heirloom Tomatoes
Mulch protects your best heirloom tomatoes by:
- Preventing Soil Splash – Which keeps the leaves nice and dry.
- Conserving Soil Moisture – Tomato plants need a consistent level of moisture to stay healthy. Mulch will prevent the soil from drying out between waterings.
- Preventing Weeds – Weeds compete for water and nutrients, stressing your heirloom tomatoes and making them more susceptible to disease.
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6. Water at the Roots
To grow the best heirloom tomatoes you should only water at the roots. Use drip irrigation or water by hand to avoid wetting leaves.
7. Don’t Over-water
Even the very best heirloom tomatoes tend to have thin skin, which makes them prone to splitting on the vine. If you over-water your plants as the fruit is setting the skin will crack and split. Over-watering can also dilute the flavor of the fruit. The best policy for watering heirloom tomato plants is to water little and frequently.
8. Experiment with Heirloom Tomato Varieties
Start out with at least half a dozen different types of heirloom tomatoes. Keep trying until you find the right strain(s) for your climate, soil and garden space. When an heirloom tomato plant is grown in the right conditions for its genetics it will thrive and fight diseases easily. With hundreds of varieties available, the best heirloom tomatoes for your garden are out there, you just have to find it.
Extended Reading
The Guide to Growing and Eating Heirloom Tomatoes
Amy Grisak teaches you all about grafting tomato plants: