Growing Tomatoes Part 2: Watering, Harvesting, and Saving Seed

In Part 1 of Growing Tomatoes, we learned how to start seeds, thin your seedlings, and the best planting techniques to get your tomatoes off to a strong start. Now we’ll discuss how to keep them fruitful during the growing season.

Tomato pruning basics

Pruning tomatoes of the determinate (bush) variety is usually not necessary. However, you may wish to do so during wet and cool summers in order to increase air circulation around the tomato plants to prevent fungal infections. With indeterminate (vine) cultivars, pruning is recommended to ensure an excellent crop.

Start pruning tomato vines about three weeks after you’ve planted seedlings in your garden. Remove all suckers as they develop so that all of the growth is on one main stem. Suckers are the stem outgrowths that appear in the crotch of each leaf. They will bear flowers and fruit just as the branches do, but we should think about concentrating resources for fruit quality and size. Learn more about pruning tomatoes in my post here.

If you’re supporting the tomato vines with wooden stakes, top off the plant once it reaches the top of the stake, so the vine doesn’t outgrow its support. Use fabric, shoe laces, or garden twine to tie the tomato vine to the wooden stake to avoid cutting into the stems. Always tie-in loosely to allow for growth and stem thickening.

How weather affects tomato growth and fruiting

The climate in your area, even the microclimate in your garden, is a significant factor in how much fruit your tomato plants will produce. Tomatoes are originally native to the coastal areas of South America and they thrive under similar weather conditions: dry air and temps in the 80-85 degree range.  During wet and cool summers, tomato blight and other fungal infections can be frequent and widespread, which sometimes result in a complete loss of plants and fruit. Early heatwaves, with temps in the 90+ range when the plants are young, slows their growth and reduces fruit set. I’ve seen flowers completely drop off the plant during an early June 100 degree heatwave. Row covers can be effective in protecting your seedlings in either of these situations.

How to water tomato plants

Tomatoes should only be watered around their root zones. Don’t water from overhead with a hose or sprinkler, as the moisture left on the leaves and fruit may encourage fungal infections. In the absence of 1″ of rainfall in a week, water your plants deeply and more often if needed during heat waves. How much is enough? Your finger is a great moisture meter – stick your index finger into the ground up to the middle knuckle. The ground should feel wet the entire length, but not saturated.

Tomatoes need consistent moisture when fruit is on the vine to avoid cracking and blossom end rot. Both conditions may appear on the fruit after a long period of dry, intense heat followed by heavy rain. Keep tomatoes well watered during dry conditions to avoid this.

Companion plant tomatoes with herbs and leafy greens

Tomatoes like the company of basil, parsley, bush beans, mint, nasturtium, marigolds, garlic, and leafy vegetables. The herbs and flowers attract beneficial insects that prey on tomato pests and the leafy vegetables love the shade that tomato plants provide when summer is at its most extreme. The herbs should also keep rabbits from making a home in the cool shade of mature plants – supposedly they hate the smell.

When to harvest tomatoes

For indeterminate tomatoes (vine type), harvesting will start with the first ripe tomato and continue through frost. Determinate tomatoes (bush type) will, for the most part, ripen within a period of one month and then the plant will begin to brown and fade away.

It’s pretty easy to tell when your tomatoes are ready to be picked. They’ll be soft yet firm to the touch, have a nice mature color, and can be pulled from the stem with a gentle tug. If it doesn’t want to let go, it’s not ready. As the date of your first frost draws near, harvest the green tomatoes which have no chance of ripening and bring them inside. Let the plant direct all of its energy into the more mature tomatoes which have a better chance to ripen before Jack Frost visits.

How to Save Tomato Seeds

Tomato seeds are one of the easiest seeds to save – just witness the thousands of heirloom tomato seeds passed down through generations.

The process is pretty simple, according to Marc Rogers in Saving Seeds: The Gardener’s Guide to Growing and Storing Vegetable and Flower Seeds: “It is the whole plant, rather than an isolated individual fruit, that you should consider (saving) in making your selection…the luscious, early-bearing plant that you’d choose first to eat is the one from which you should save seed.”

Steps to save tomato seeds:

• Let the first cluster of tomatoes ripen completely, then pick the best of the best to save (the earliest producing fruit contains the most vigorous seed)
• Cut the tomatoes in half vertically and scoop out the seeds and pulp.
• Place seeds and pulp in a mason jar with a small amount of water and shake gently (first, let the water sit for a few hours at room temperature so the chlorine evaporates).
• Leave the jar sit 2-4 days, shaking occasionally, until the tomato seeds sink to the bottom of the jar. Add more water and shake again to separate and clean the seeds.
• Remove the tomato seeds from the jar and allow to air dry on a paper towel.

When the seeds are fully dry, store them in a white envelope inside a mason jar. Keep them cool until next season, preferably in the back of your refrigerator, but never let the seeds freeze. Make sure you mark the envelope with the tomato cultivar and the date harvested and any other information you might find useful.

Note that it is not advisable to save seeds from hybrid (F1) tomatoes, as the fruit which comes from them may not resemble the fruit of the parent plants.

How to store tomatoes

Do not store freshly picked tomatoes in the refrigerator, as they lose flavor quickly – they’re best held at room temperature. If your harvest exceeds the amount which you can eat before they go bad, there are a few ways to store tomatoes for later use.

Freezing is quite good. If you’ll be using them in the next month or two, simply chop them up and freeze them in Mason jars. You can also freeze the tomatoes whole. If you’ll be holding them longer, par-boil them, score the skin while hot, peel, and then jar and freeze. This is fantastic if you make a lot of sauces over the winter.

I find freezing to be the simplest and fastest method if you have the space and are not subject to frequent electrical outages. Of course, if you have enough tomatoes, you can make a vat of sauce right away and freeze that for your winter pasta dishes. Other ways of keeping tomatoes are by freeze-drying or by canning. Learn the basics of canning in this post.