Knowing how to propagate tomatoes saves money and keeps a garden stocked with top-notch plants. This year’s best performers can turn into next year’s crop without spending a cent. It’s a practical way to grow the same juicy varieties that thrived this summer.
Propagating new plants is an important part of learning how to grow tomatoes. The practice allows you to replicate favorites – whether it’s a sweet cherry tomato or a hefty beefsteak. There's no need to gamble on new seeds or nursery stock. Plus, you already know these tomato varieties will handle local soil and weather like champs.
Three solid methods make propagating tomatoes straightforward. And, if you're not ready to let go of your existing plants, then it's worth knowing that you can actually overwinter tomatoes indoors. Years of messing around in the dirt have honed these steps, with a few oddball tips thrown in to boost results. Here’s the rundown for getting free plants ready for next spring.
1. Saving Tomato Seeds
Saving tomato seeds is a dead-easy way to propagate plants for any heirloom tomato variety. No more crossing fingers on seed packets that might not deliver the same punch as last season’s tomatoes! One of my favorite heirloom tomatoes is the black cherry, which has such a unique, complex flavor. Every year, I save seeds and start a new crop the following spring. You can try growing it yourself with these seeds from Burpee.
However, if you are growing hybrid tomatoes, then this method will not recreate the same plant – and may not work at all. It's possible you will cultivate a new delicious variety, or it may be a total flop. So, unless you love experimenting, it's best to use other methods for hybrids.
To save seeds from heirlooms, pick a ripe tomato from a strong plant, slice it open, and scrape the seeds and goo into a jar. Add a bit of water, cover it loosely, and let it sit for a few days. That fermentation kills off diseases.
A trick not everyone mentions is to scoop off the moldy top layer after fermenting. Miss that step, and seeds might not sprout well. Rinse them clean, spread them on a paper towel to dry, and tuck them in an envelope, like these Joyberg Kraft Seed Saving Storage Envelopes from Amazon. Keep them somewhere cool and dry for spring.
2. Take Cuttings
Rooting tomato cuttings works great for propagating plants from healthy growers. Late in summer, grab clean, sharp pruning shears – Fiskar's Bypass Pruning Shears, available on Amazon, are perfect for the task – and snip a 6-inch stem from a side shoot, right below a leaf node. Strip off the lower leaves, pop it in a glass of water, and set it on a sunny windowsill. Roots show up in about a week.
Remember to swap out the water every couple of days. Stagnant water can stall cuttings, especially for chunkier varieties like beefsteak. When roots hit an inch, plant them in a pot with damp soil and keep them indoors, ready for spring transplanting. If your new plants get too big too soon, then repeat the process.
3. Layering Side Shoots
Layering side shoots is a low-fuss way to propagate tomatoes. Find a bendy side shoot low on a healthy plant and ease it down to the dirt. Bury a few inches of the stem, leaving the tip poking out, and pin it with a small rock or wire. Roots form in a couple of weeks.
Lightly scrape the buried stem with a clean knife beforehand. That little nick speeds up rooting for stubborn plants. Once roots take hold, cut the shoot free and pot it up for next season’s garden. Soil Sunrise's Plant Propagation Potting Mix, available on Amazon, is perfect for cuttings.
4. How to Overwinter Tomato Plants in Pots
To save a favorite tomato plant for next year, bring it indoors for winter. Pick a smaller type, like a cherry tomato, dig it up, and settle it into a pot with fresh soil. Snip it back to about a foot (30 cm) tall and tuck it by a south-facing window where sunlight pours in.
Alternatively, set plants up for a long harvest by investing in a planter on wheels, such as the Vego garden tomato planter box with trellis, available on Amazon – it can be easily rolled indoors when temperatures drop and is self-watering for minimal maintenance.
A trick many gardeners miss is to water sparingly. Drenching the soil indoors spells disaster with mushy roots. Keep it just damp and give the leaves a quick mist now and then to fake that summer breeze. Another tip is to turn the pot every few days for even light. This keeps the plant from leaning like it’s chasing the sun. Alternatively, invest in a grow light, like this GooingTop LED light from Amazon.
Tips for Successful Tomato Propagation
Pick robust, bug-free tomato plants to steer clear of future headaches. Clean tools with a splash of rubbing alcohol (available on Amazon) for a spotless start. Write down the variety and date on seed envelopes. Jumbling up your beefsteak and Roma isn’t fun when you are expecting one or the other.
Warm soil, near 70°F (21°C), gets cuttings and layering going quicker. You can also set pots on a sunny stone path for a day to soak up extra heat. A heat mat, like this Vivosun design from Amazon, can make a difference in chilly houses. For overwintered plants, watch for pests like aphids on tomato plants and give them at least 6 hours of good light. These steps set up next year’s tomatoes for a strong start in spring.
