Guest post by Arzeena Hamir
Tomatoes are one of the easiest vegetables to grow from seed. However, unless you live in the tropics, your summers are probably too short to direct seed these heat loving plants. Starting tomato seeds indoors gives them a jump on the season, especially with late maturing varieties. Start seed 6-8 weeks before your last frost. Check almanac.com if you’d like to check your frost dates.
Did You Know?
- Tomatoes are native to South America.
- They were first cultivated by indigeneous peoples in prehispanic Mexico.
- The fruit is botanically a berry.
Tomato seeds themselves are easy to handle and can be planted in any type of container you have around the house: yogurt containers, milk cartons, etc. Try not to use too small of a container (egg cartons for example) or else you’ll be watering more frequently.
The key to starting tomato seed is to keep the seed moist. Pre-moisten the potting mix so that it’s wet but not soggy. When you squeeze it in your hand, no water should come out. The soil should form a ball that falls apart when you poke it. Fill your container and place one or two seeds on top, covering them lightly with more soil. Next, cover the container with either a plastic dome or plastic wrap. Not only does covering prevent the soil from drying out, it prevents you from overwatering the soil as the seed is germinating.
In addition to moisture, warm temperature is the key ingredient to helping tomato seeds germinate. At 75-80° F, seedlings will emerge in just three to five days. Bottom heat is best so place your containers in a warm spot like on top of the water heater or even on top of the VCR. Alternatively, you can use heating cables or a heating mat under the containers.
Once the seedlings are up, move them off the heat and provide them with lots of light. If you have a bright, south-facing window, keep them there. However, if you notice that your seedlings are getting lanky, it’s an indication that you need to provide supplemental light. Grow lights or fluorescent shop lights can be used to keep plants short & stocky. Suspend them close to the plants, no more than four inches from the top of the leaves.
Once the seedlings have developed at least one set of true leaves, pot them up into their own individual containers. Each time you do this, add some fertilizer to the soil mix. I find worm castings to be a great source of organic nutrients that won’t burn the seedlings. Other options include compost or half-strength fish fertilizer.
Each time you pot up your seedlings, take off the bottom two sets of leaves and bury the entire stem. Why? Tomatoes have this wonderful ability to sprout roots along their stems. They are, after all, related to potatoes. Burying the stem & stimulating more root production ensures that the seedling has a well established root system that will withstand the fluctuating moisture conditions in the garden.
Arzeena Hamir is an agronomist and garden writer based in Vancouver, BC. She has worked in the organic gardening industry for 8 years as a consultant and trainer. When she’s not planting peas or harvesting zucchini, she runs Terra Viva Organics.