Growing Native Plants From Seed: Cultivating Backyard Biodiversity

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Participants at our seed sowing workshop preparing their containers.

On Sunday, February 25th, the Iroquois Ridge Library “Creation Zone” was indeed full of a flurry of creative activity. The eager participants at our “Winter Seed Sowing” workshop were certainly not afraid to get their hands dirty for the sake of growing biodiversity. They all went home with recycled containers full of soil and native plant seeds (milkweed and Canada anemone), envisioning the tiny plants that will hopefully spring to life in a few months.

Backyard Biodiversity

Growing native plants from collected seed is one way that we can help support local biodiversity. As Oakville becomes more and more urbanized, natural green space continues to be replaced with asphalt and concrete. This makes it more important than ever to foster “backyard biodiversity,” bringing nature right into our urban areas in the small patches of green space all around us. Think about your front lawn – how many species are there? If your yard is mostly turf, then that number is probably pretty low. It’s time to turn our urban monocultures into sanctuaries for biodiversity!

But why is biodiversity so important? Well, biodiversity is essential for proper ecosystem functioning. A greater diversity of species, families, and habitats supports a wider variety of ecosystem functions – functions that we need to survive. These include filtering groundwater, creating oxygen, removing pollutants from the air, cycling nutrients, supporting pollinators that in turn pollinate our food crops…the list goes on. Furthermore, there is tons of research out there showing that greater biodiversity means greater resilience to change. Ecosystems that support a wide variety of species are better able to adapt to new conditions, such as those created by climate change. This means that restoring biodiversity can help preserve our green spaces in the future.

This native plant garden supports a wide variety of native insects, including pollinators. Plus, it looks beautiful!

Planting Native

If we want to foster biodiversity, native plants are a good place to start. Native plants support native insects (including native pollinators), who feed native birds, who can become meals for native predators…you get the picture. A diverse food web helps keep the ecosystem in balance, so we don’t get huge population explosions (like last year’s fall cankerworm infestation). Since native insects have evolved to feed on native plants, native plants usually support more insects than many of the exotic plants that you’re used to seeing at your local nursery. For example, native oaks can support 534 butterfly and moth species! In contrast, the non-native ginkgo tree supports zero butterfly and moth species here in Ontario.

Swamp milkweed. Milkweeds are the larval host plants of the monarch butterfly.

A great example of the co-evolution between native plants and insects is the monarch butterfly and milkweed. Monarchs will only lay their eggs on plants in the milkweed genus. The monarch has evolved to be immune to the toxins in milkweed leaves, and its caterpillars eat the leaves, ingesting the toxin and gaining a defense against predators. However, due to a loss of milkweed, as well as habitat loss in their overwintering grounds, monarch populations have experienced serious decline. So, by planting milkweed, we can help support our beautiful monarch butterflies. There are many other native insects that are specialized to rely on a narrow range of plant species (find a list of larval host plants here). Without these plants, the insect species will eventually disappear.

There are a number of benefits of planting native species, besides the fact that they support native pollinators. Native species are adapted to our climate and soils, meaning they usually require less water and less effort to maintain, and are more winter hardy. Our deep-rooted native prairie plants are also great at holding soil in place to prevent erosion. Finally, when we see native biodiversity all around us, we gain a better appreciation for it – and we pass on this appreciation to the next generation of conservationists!

There are sometimes people who protest the planting of native plants. We find this pushback is usually based on common misconceptions that can be dispelled through education. Here are some common myths (and the truth) about native gardens and pollinators:

  • Myth: Native gardens are weedy and messy!
    • Truth: with proper plant selection and maintenance, native gardens can be beautiful! Make sure you consider your sun, soil and moisture conditions and try to mimic native plant communities when designing your garden
  • Myth: We need to save the honey bee!
    • Truth: While is is true that honey bee colonies have been experiencing some substantial losses, it’s important that we remember that there are many native bee populations that need our help! Many of these species are disappearing right under our noses, and are not receiving the same amount of attention and research as the non-native European honey bee. By planting native and providing nesting habitat for our native bees, we can help support their populations too.
  • Myth: If we plant native gardens, we’ll have more bees and they will sting us!
    • Truth: Most of our native bees do not even have stingers and, even if they do, they are so small that you wouldn’t even feel it. Other than the bumble bee, our native species are not colony-forming and so do not have the need to defend their colony or queen.
      Ragweed is the most common source of late summer allergies. Photo by Krzysztof Ziarnek (Source: Wikipedia).

      Plus, a foraging bee is a busy bee, and a busy bee isn’t going to pay any attention to you! So, you don’t need to worry about bee stings.

  • Myth: I’m allergic!
    • Truth: Although many people attribute their summer allergies to native goldenrod, the real culprit is non-native ragweed. Goldenrod pollen is too heavy to become airborne, so it relies on insects to transport it from flower to flower. Ragweed, on the other hand, has very light pollen that blows around in the wind and can easily get blown right up your nose! Since goldenrod blooms at the same time as ragweed and has a much showier flower, it often gets the blame. But rest assured, your native goldenrod won’t do you any harm.

How to Grow Native Plants

So, now that you’re convinced that growing native plants is a great way to cultivate biodiversity, you’re probably wondering how to get started. Here we will focus on growing native plants from seed. We will describe the methods with milkweed in mind, but the same basic steps will work for many other native plants. Be sure to research harvest and stratification methods for individual species (Here’s a great resource for germination data).

Harvest, Clean & Store:

It’s best to harvest milkweed seeds in the fall, just as the pods are starting to split. If you wait until the pods are fully open, it’s a much messier process! Be sure to harvest seeds from your seed zone, so they are locally adapted to the conditions. As a rule of thumb, you should never harvest more than one-third of the available seeds on the plant or in the patch. Clean the seeds out of the pods and put them in a labeled paper bag in the fridge.


Stratification is the process of breaking the seeds’ dormancy, usually by providing it with a cold period (cold stratification) that mimics natural conditions. In nature, seeds would go through a winter before germinating, so you need to provide your seeds with that “winter” experience! For most species, including milkweed, providing a period of cold and moist followed by warming will do the trick. However, it’s important to research your individual species, because some have unique requirements. For example, New Jersey Tea, which is adapted to forest fires, requires high heat (think boiling water!) followed by a cold period in order to break dormancy.

There are 3 main ways to stratify milkweed seeds:

1. Fall planting outdoors. Simply sow the seeds in your garden in the fall. They will go through a natural winter and should germinate in the spring. Pros: less work, plants are already in their desired locations in the spring. Cons: requires you to already have your seeds and a prepped garden plot and design in the fall, doesn’t allow you to share seedlings with your friends.

Fridge stratification method.

2. Fridge method. Place your seeds in the fridge with a paper towel, or in the fridge/garage in flats or pots for 2 to 3 months. After the cold treatment add heat and light, gradually acclimatizing (“hardening off”) seedlings and transplanting outside after the danger of frost has passed. Pros: can plant seedlings anywhere in the spring and share with others. Cons: requires space in the fridge/garage, and other members of the household might protest to the “seeds in the fridge situation,” seeds still need some attention (maintaining moisture).

3. Winter Sowing. See methods below. Pros: Easy, cheap, good for starting a lot of plants, can plant anywhere in the spring and share with others. Cons: seeds still need your attention – you can’t leave for an extended vacation!

Winter Sowing

Winter sowing is a great method if you want to start lots of seeds but don’t have extra room in your fridge. Here are the basic steps:

  1. Prep Containers. Try using recycled clear plastic produce containers (like those that hold lettuce, strawberries, and mushrooms), milk jugs or 1L plastic water bottles. Deep tupperware also works well. Make sure your containers have holes at the bottom for drainage and vents at the top so water can get in – a sharp pair of scissors should do the trick!
  2. Label! You should use a waterproof marker to label each container with the species, seed source and collection date. This can prevent a lot of confusion a few months down the road!
  3. Moisten soil. Try using sterile soil (e.g. seed starting mix) to prevent the growth of mold, and wet the soil lightly. It should be wet enough to clump, but not dripping. Aim for a soil depth of 3″.

    Recycled produced containers are great for the winter sowing method. Be sure to label them!
  4. Sow seeds. The proper depth will depend on the species – milkweed likes to stay right at the surface. Place the seeds on top of the soil and then lightly sprinkle some dry soil over top to hold the seeds in place.
  5. Mist soil and cover containers. Place a translucent or clear lid on the container, ensuring there are some vents at the top to let water in
  6. Place in a location with light and moisture. Place your containers OUTSIDE any time after the winter solstice (remember, they need 2-3 months of cold), ensuring that they will receive indirect light, as well as rain and snow. Ensure the soil stays moist until germination, which should occur sometime between March and June. This may mean misting the soil during dry periods.

Learn more about the winter sowing method here.

After Germination: Pot up and Plant

Once your seeds germinate, gradually increase their exposure to sunlight. Once they have 2 ‘true’ leaves (the first two leaf-like things that come up are not true leaves, but cotyledons), you can transplant them into a larger container or pot (recycled yogurt containers with holes in the bottom work well), and place the pot in a protected location away from direct sunlight. A location that receives morning sun is often ideal.

Once the roots have reached the bottom of the container, your plants are ready to move to the garden!

Other ways to support pollinators in Oakville

If you’re looking for more ways to support pollinators in Oakville, join us on April 7th and/or April 14th for our “How to Plant a Pollinator Patch” workshop series! Learn more about native bees and how to make your backyard an oasis for pollinators, plus learn how to prep a site, choose species, design, plant and maintain a pollinator patch. Then, you can try out your skills by helping us design a new Oakvillegreen pollinator patch! Find out more and register HERE.

As we mentioned, native trees support tons of native pollinators. Our new Oakville Backyard Tree Planting Program is a great way to have a native tree planted in your yard for a subsidized cost. The program includes a consultation with an arborist, a 5 to 8 foot native tree, delivery and planting service. Find out more HERE.

We also hold a native tree and garden kit sale every spring, where you can order native trees, shrubs and perennials via our online store and pick them up the municipal greenhouse in May. Sign up for our e-newsletter to receive an update when we open up our online ordering system later this month!

You can visit our “Supporting Pollinators in Oakville” webpage to learn more about what we’re doing to support pollinators, and how you can help.

So, as you start to plan ahead for your garden this year, we’ll hope you’ll consider planting native plants to support the birds, the butterflies and the bees!