March 2025 Newsletter - Swallowtail Native Plants

There are several different ways to grow native plants from seed. This month I am going to focus on sowing them indoors under lights. If you have already cold stratified your native seeds in the fridge, the next step is to take them out, sow them in pots and put them under grow lights. I have been growing native plants from seed this way for the last four years. It works.

Why grow native seeds under lights?

As I started to write this month’s newsletter I wondered why I grow native plants this way. It is labor intensive and expensive. The shelving units take up a lot of space in my basement. I eventually found the culprit: tomatoes.

Tomatoes *(Solanum lycopersicum*): Not native to Ontario!

I did not begin gardening many years ago by trying to grow thousands of native plants from seed. I began by purchasing vegetable and flower plants for my home garden. As we all know, gardening is addictive. Once I bought a few plants I soon wanted many more plants. I quickly realized that plants are expensive, but I could have lots of plants for less money if I grew them from seed.

Now tomatoes enter the picture. Of course I wanted to grow tomatoes in my garden, they are infinitely more delicious than store bought tomatoes. But tomatoes must be planted after the last frost. They have no adaptations to cold temperatures, so the plants die when the thermometer dips below zero. Most of the vegetable and flower seeds that are available to purchase at garden centers are actually non-native tropical species. Tomatoes originally came from western South America, where they grow as perennials.

I could sow my tomato seeds in the ground in May, but if I sowed them indoors in March they would be a nice sized plant by May. Then I would have more tomatoes and I would have them earlier in the summer. So I bought some lights and learned how to start tomato plants from seed indoors.

When I started growing native plants from seed, I followed the same steps I used for tomatoes, with the additional step of first cold moist stratifying my seeds in the fridge. While there is only one way to grow tomatoes, there are several different options for growing native seeds.

White Vervain seedlings (*Verbena urctifolia*) – native to Ontario

Native plants are adapted to our climate. Most of them are perennials. The more I work with native plants, the more I have to unlearn everything I know about growing plants. Many native plants can be planted in the garden before the last frost. You can grow your plants from seed all summer and then plant them in the fall. You can winter sow them. There are a lot of options that are not available if you are trying to grow tomatoes.

I still grow native plants under lights (I don’t grow tomatoes anymore!). If you have seeds that you have cold moist stratified in the fridge and you are ready to plant them indoors, here are some tips and tricks to help you be more successful.

Growing Native Plants Indoors Under Lights

Sowing your seeds

Many native species require light to germinate, especially if the seeds are very small. Sow these seeds directly on top of the soil and do not cover them. Gently mist or water the seeds to make sure they have good contact with the soil. Do not let the surface of the soil dry out. I put clear domes over the seedlings until they have their first true leaves and then I remove the domes.

If you have taken your seeds out of cold moist stratification they might be all stuck together in a soggy clump. You can mix the seeds with a small amount of dried sand and then spread the sand-seed mix on top of the soil for more even distribution.

Lights

You do not need fancy expensive grow lights, any sort of light will do. Energy saving, LED lights are good for the environment.

Place your plants as close to the light source as you can without the leaves actually touching the lights. As your plants grow you will need to adjust the height of the light or adjust the height of the plants, your choice. This will help the plants to develop sturdy stems. If the plants do not have enough light they grow long, thin, weak stems.

Watering

Just like Goldilocks and the three bears, seedlings need just the right amount of water, not too little, and not too much. I water my seedlings from the bottom and let the soil soak up the water. After an hour I come back and drain off the excess water. I can tell when they need to be watered by the weight of the pot. A heavy pot does not need to be watered, a light pot needs watering.

Moving them outside

This is another area where I needed to unlearn some of my tomato gardening knowledge. With native plants you do not necessarily have to wait until late May to move your plants outside. You can take your cues from nature. If you are growing sedge plants (Carex sp.) and you look outside in late April and see sedges growing, you can probably move your plants outside and they will be fine. However, if you are growing Spotted Joe Pye Weed (Eutrochium maculatum) and there is no sign of any leaves growing out in nature in April, you’ll want to wait until later in May.

I hope this post helps if you happen to be sowing your native seeds under lights. Next month we’ll see how the winter sown seeds are doing. Mine are currently buried under two feet of snow!

If you have any questions, please feel free to send me an email. I would love to know what challenges you face growing native plants from seed.

email: swallowtailnativeplants@gmail.com

Happy growing!

Andrea

owner – Swallowtail Native Plants