Are My Plant Seeds Native Enough? – The Native Plant Gardener

There’s a lot of activity on the various native plant gardening Facebook groups these days about winter sowing. I’ve never tried it, but it makes total sense to do what Mother Nature does – set your trays of soil with seeds outside and let the natural refrigeration of winter do the cold moist stratification for you.

Trays with seeds ready to be left out in the cold – photo by Pat Fowler, Middlesex Centre Pollinator Team

In my research for native plants sources, I have come across a handful of companies that specialize in native plant seeds. In fact, some ONLY sell seeds and not plants.

Have you ever asked yourself where they get the seeds? Does it even matter? A milkweed is a milkweed, regardless of where it is growing, is it not? Well, that depends.

Rare Native Plants

In southwestern Ontario, where I live, we are in what is often referred to as the Carolinian Life Zone. Here our climate and soils are similar to places far south of us – as far as the Carolinas in the US. That means that many plants are native here that aren’t found naturally anywhere else in Canada. It also means we’re at the northern limit for many of these plants, and occasionally the populations of these plants are found only in isolated pockets here and there.

Take, for example, Stylophorum diphyllum, or Wood Poppy, known to be found naturally only in a few isolated locations around London, Ontario before we started spreading it through our gardens.

Or what about Cercis canadensis, the Eastern Redbud, a beautiful small tree originally known only from Pelee Island in Lake Erie (Canada’s most southerly point – at the same latitude as northern California). However, because of it’s size and spectacular spring colour it now adorns many yards throughout southwestern Ontario and even points north and east of here.

Wood Poppy (*Stylophorum diphyllum*) is a beautiful shade plant

Two Sides to the Argument

There are two sides to the argument about whether this is a good idea or not, and I still haven’t entirely made up my mind which side I’m on. Both sides have much merit.

The first argument is that these isolated pockets may hold unique genetic traits that could disappear though cross-breeding with plants that evolved elsewhere. And until we have done genetic testing to show otherwise, we should not introduce these other plants. To loosely paraphrase Joni Mitchell, “We won’t know what we’ve lost if it’s gone”.

Wood Poppy is known naturally in only a few isolated spots in Ontario

At the other end of the spectrum, there is the argument that rare, isolated pockets of such plants are in danger of being lost due to habitat destruction, climate change, pollution, etc. and that in order to keep seeing them, we need to plant more. After all, humans are the main reason many have disappeared over the last 200 years, or are on the brink of disappearing now. And since there are so few left in the wild here, we need to source the seeds elsewhere.

The other argument for bringing seeds or plants in from other areas is that very small, isolated pockets of plants may reach a genetic bottleneck where inbreeding can lead to weakened plants that are more susceptible to the stressors that are placed on them. Only by bringing in outside plants can we bolster the genetic diversity and, hopefully, stave off extinction.

Native Plant Sources – Choices

I recently placed an order for some seeds from a company in Ontario because they were the only company offering the plant I have been looking for for some time. I was told the seeds for my plant were ethically sourced in Ontario.

However, for another plant I was curious about, I was informed the seeds were from the US. They ignored my question about WHERE in the US, but my guess is that it was likely Prairie Moon Nursery in Minnesota as that is one of the larger sources of native plants seeds and many nurseries here in Ontario use seeds from there.

The latitude of Minnesota is roughly the same as southern Ontario so those plants should be hardy here. However, the original stock from which those seeds were sourced may be genetically quite different than the ones that actually evolved here. It has been reported that Asclepias tuberosa – butterfly milkweed – plants tend to be a lighter yellow in the west and a darker orange in the east. By the same token, Ratibida columnifera (not actually native in Ontario) – sometimes called Mexican Hat – is mostly pure yellow in Canada but mostly a burnt red in the southern end of its range. By bringing in different genetics, we may lose the plants that have evolved here, and any uniqueness they offer.

The genetic variations in Butterfly milkweed (*Asclepias tuberosa*) means it tends to be paler the farther west in its range and darker in the east. Should we be mixing the genetics by planting seeds from outside our own area?

The genetics of colour for Mexican hat (*Ratibida pinnata*) tends to show variation on a north/south axis. Plants at the north end of its range tend to be yellow while those in the south are dark red, while the ones in the middle are a mixture of red and yellow. However, the middle photo shows a few dark red plants in what was otherwise a sea of yellow in Manitoba, Canada showing that the colour is not always constant.

Another native Ontario plant from my wish list that this company offered for sale was out of stock. I was shocked, though, when they said they were just waiting on their shipment from England. What? A native Ontario plant and it is being sourced from across the ocean?

A few years ago, someone told me that seeds for a plant I was looking for was available on Amazon. After doing a bit of digging, I discovered that these seeds were “shipped from China”. I didn’t buy them.

All of this is to say, whether you’re winter sowing or spring sowing, ASK where your seeds came from. If there just AREN’T any seeds or plants available for that one plant you really MUST have, only you can decide what limits you’ll set on the acceptable distance from where you live to where they are sourced from. As the demand for native plants continues to grow, local sources will continue to pop up. If they know that the provenance of the seeds is important to native plant gardeners, they will look closer to home to source their seeds. And eventually (I hope) more local farm operations will start to grow native plants to supply the market with seeds.

In the photo below, the Irvine Ranch Conservancy in California is one of many commercial native-plant producers in the US (photo courtesy of Irvine Ranch Conservancy). I was unable to get a photo from a local commercial producer in time for posting. This level of production is possible here, too, and will happen if we demand local seeds.

Happy native plant gardening.