5 expert secrets on how to grow 100 lbs of tomatoes in 20 square feet. Lots of vegetable gardening tips on soil, care, trellis ideas & more!
Last year, inspired by some amazing organic gardens we visited, we experimented with new ways to grow tomatoes.
Our tomato plants were more vigorous and healthier than they have ever been!
In a 20 square foot area, we harvested over 100 lbs of delicious tomatoes from just six “Early Girl” tomato plants , a popular variety that can be easily found in most nurseries.
Today I am excited to share with you the tips and tricks we learned on how to grow tomatoes like an expert and get a huge harvest!
Tips number 1, 3 and 4 are something new we tried that made all the difference!
Before we go into details of the tomato growing techniques, these are a few basics that apply to all vegetable gardening: plenty of sun, good soil, and productive varieties that are suited for your climate.
The easiest way to build great soil on any site is to create a simple raised bed. Here are lots of tips and tutorials on DIY raised bed gardening-
Tomatoes come in determinate and indeterminate varieties, which is written on the plant label.
Determinate tomato varieties are small compact growers with a short harvest season, they are great for small space gardens, pots and containers. Our tips 3 and 4 will not apply to these.
Most of the great tasting and heirloom tomatoes (for example- “Early Girl”, “Cherokee Purple”, “Sweet 100“, “Brandywine”) are indeterminate tomatoes, which means they continue to grow and produce tomatoes all along the stems throughout the growing season. These are the tomatoes we prefer to grow.
Grow Tomatoes Secret 1 : Tomatoes love warm soil temperature and lots of direct sunlight.
“The earlier we plant, the sooner we get our first tomato, right? ” Actually, no. Tomatoes should not be planted outdoors until after the average last frost date for your area, although you can start seeds indoors 6-8 weeks before the last frost date.
Tomatoes hate cool soil temperatures. The ideal soil temperatures to grow tomatoes are between 70 – 90 degrees Fahrenheit. Tomato plants love full sun locations with at least eight hours of direct sunlight a day for healthy growth and fruit production.
Temperatures dipping below 55 degrees Fahrenheit stops plant growth. The less active the growth cycle, the more likely the plants will have insect and disease problems such as blossom end rot, early blight, etc.
In most places, the night time temperatures can be quite cold in March, April, or even May. To solve this problem, we used the dark plastic mulch method which we learned from amazing gardeners who grow tomatoes successfully even in challenging climates.
Open up a few black plastic trash bags, lay them on top of the soil, secure along the edges with wood planks or rocks. Cut 3″ to 4″ diameter holes for the transplants. We planted our tomatoes on a 30″x30″ grid.
The plastic was able to raise the soil temperature by 10 – 20 degrees Fahrenheit during the day, and hold the heat better at night, which was perfect for most spring days and nights when temperatures are between 45 – 65 degrees.
As the weather gets warmer by summer, the plants will have enough leaves to shade the plastic and prevent it from getting too hot. We could tell how happy the plants were. In a couple of weeks, the seedlings were growing rapidly and looking super healthy!
Another benefit: When soil moisture level fluctuate too much due to weather and uneven watering, tomato plants can drop blossoms, or develop blossom end rot. This black plastic mulch is great for keeping a good soil moisture level.
Grow Tomatoes Secret 2 : Plant deep in compost rich soil
Compost is rich in nutrients for healthy and faster plant growth, it also promotes soil microbes which aid plant growth, and improves soil structure in sandy or clay soil so the soil can better retain water and nutrients.
Here are 25 best DIY compost bin ideas.
We have compost rich soil, and we don’t even fertilize our tomatoes. However, if you want to add additional fertilizer, choose an organic fertilizer with an NPK ratio that is higher on the P number. NPK stands for nitrogen ( for foliage growth ), phosphorus( for fruit production) and potassium( for healthy roots). This Dr. Earth 4-6-3 tomato fertilizer is a great choice.
Is manure a good fertilizer for tomatoes? Manure contains too much nitrogen, which is good for foliage growth when plants are small, but not very helpful for flowering and fruiting as the plant grow.
Prune off the bottom leaves and plant about 2/3 of the plant underground.
Because tomato stems grow roots easily, we can propagate new ( and free!) plants in just a week from stem cuttings of a big plant! Tutorial here-
Tomato plants have this amazing ability to grow roots along the buried stems, which will make the plants stronger.
Secret 3 : Prune tomato plants fearlessly.
Have you grown a huge tomato plant, only to get a ton of leaves and very few fruits? Then it just wilts and dies?
The best solution is to prune tomato plants regularly. Pruned plants allow more sun light to come through and more air flow. The leaves dry faster after a rain, so they are less susceptible to the diseases such as blights.
The orange arrow indicates the main stem, and the blue arrows indicate the side shoots / suckers which can grow into a stem. The goal is to leave only 1 or 2 stems growing ( some say up to 4 stems ), and prune off all the suckers.
It is very easy to miss one until it has grown too big. So do this at least twice a week, and be ruthless!
See how thick and healthy this main stem is? Instead of growing 50 to 100 stems, the plant is able to concentrate it energy on the main stem and keep producing fruits. ( This method is suited to indeterminate tomatoes which we talked about at the beginning.)
Secret 4 : Grow tomatoes vertically to improve air circulation and maximize sunlight.
You can grow healthy tomato plants using a DIY trellis. The other new thing we did which made a huge difference is to build a tall trellis and tie strings between the top and bottom rail to wrap the tomato vines around as they grow.
You can adjust the tomato trellis height to 4 to 5 feet tall, especially for smaller tomatoes such as cherry tomatoes and plum tomatoes.
We made our tomato trellis from pallets, using 2x4s as the main X frame and 1x4s to join them together. Here are tips on where to find and how to take apart pallets!
As mentioned in tip #3 we prune each plant to keep only two stems growing. Each stem wraps around a string, keeping good air circulation and making any pruning and harvesting super easy.
We used thin jute twine but they deteriorated toward the end of the season. We will use heavy duty garden twine in future. ( This method is suited to indeterminate tomato plants which we talked about at the beginning.)
You can also use other trellises. Check out these 24 best DIY garden trellis ideas.
Secret 5 : Keep tomato plants dry.
Gardeners who grow tomatoes know how quickly disease such as blights can make the foliage turn dark and brittle, and kill the tomato plants. To prevent early and late blight, water the plants at soil level and keep soil or water from getting onto the leaves.
It is easy to water under the plastic mulch: just insert a hose from one end, or install a soaker hose before laying down the plastic.
We planted these tomatoes in early May. Believe it or not, our coastal San Diego weather is not the best for growing tomatoes.
Because of these new methods we tried, we were able to get a much bigger harvest than ever in not-so-ideal conditions.
Between July and early September, we harvested over 100 lbs of tomatoes, usually around ten tomatoes at a time.
We did let some plants grow to 5 stems which lead to disease build up at the end. I think by keeping the plants better pruned we can actually grow over 200 lbs in 20 square feet!
You may also love: DIY strawberry tower with built-in reservoir!
Here are a few additional resources on growing tomatoes you may like to explore:
Bonnie Plants guide to growing tomatoes in different climates, the Almanac’s guide on planting and harvesting tomatoes, how to build sturdy tomato cages via instructables, one of our favorite tomato seed source Baker Creek, and our collection of 35 creative DIY container veggie garden ideas!
Happy growing! See you soon!