Heritage seeds, hybrid seeds, what is cross-pollination?

I don’t know about you guys, but when I first ventured into the world of vegetable gardening, I heard these words a lot without a clue what they meant when it comes to the garden. Today I’m going to lay it out simply. What are the differences between the seeds and what can cross-pollinate with what?

Heritage Seeds (or heirloom seeds)

An heirloom is defined as something special, of value, handed down from generation to generation. It’s the same with heirloom (or heritage as they’re also known) seeds. These seeds are from plants grown by our ancestors and passed down, each baby seedling a pretty much exact replica of the parent plant.

Heirloom seeds are open-pollinated and will produce seeds that are ‘true to type’. This means they are either self-pollinated or pollinated by a plant in the same species to then produce offspring that are akin to their parent plant.

Hybrid Seeds

Hybrid seeds are the seeds produced by plants that have been cross-pollinated. This means the pollen from one variety of plant has been transferred to a different variety of plant in the same species. The produce that grows once the plant has been pollinated will be the same, but the seeds saved from that produce will not be the same as the parent plant.*

A spaghetti squash female flower pollinated by a male zucchini flower will still produce a spaghetti squash. If you were to save the seeds of that spaghetti squash that formed however and plant those, you would end up with a zucchini/spaghetti squash hybrid cross.

*Corn is different. When one variety of corn is cross-pollinated with another variety of corn you will see the cross-pollinated results in this year’s harvest.

Hybrid seeds produced by seed companies are made very deliberately. Plants will be picked based on things like their size, disease resistance, and yield and cross-pollinated to produce an elite sort of plant. As the offspring produced by that plant won’t be the same as the parent and you don’t know what you’ll get, you have to rebuy hybrid seeds each year instead of seed saving.

What can cross-pollinate with what?

For vegetables that are self-pollinating such as tomatoes, peas and beans, cross-pollination is very rare. For those that need insect help to pollinate, cross-pollination can be really likely.

Plants are sorted into families and each family has groups called Genera (or genus for a singular group.) These genera are made up of many species.

For example the cucurbit family, Cucurbitaceae (which includes cucumbers and pumpkins) is made up of 95 genera. Those genera are made up of over 950 species. As it is such a large group, there is often confusion about what can cross with what.

As a general rule, plants only cross-pollinate with the plants of the same species.

Here are three main genera of cucurbits: Curcurbita, Cucumus and Citrullus.

• Cucurbita: This genus includes pumpkins, squash, zucchini.

  Within this genus, there are three main species

  a) Cucurbita maxima: A few examples include: banana squash, buttercup squash, Jarrahdale pumpkin, Turks turban, Queensland blue, crown prince…
  b) Cucurbita moschata:  A few examples include: butternut squash, tromboncino…
  c) Cucurbita pepo:  A few examples include: zucchini, patty pan squash, acorn squash, spaghetti squash, baby bear…

• Cucumis: Cucumbers and some melons (rock melons,kiwano, honeydew)

• Citrullus: Watermelon

A buttercup squash (c.maxima) will not cross-pollinate with a butternut squash (c.pepo). 

A zucchini (c.pepo) will cross-pollinate with an acorn squash (c.pepo.)

A cucumber will definitely not cross with a Jarrahdale pumpkin as they aren’t just a different species, they’re a different genus.

Brassicas

Another large family of vegetables is the brassica family in which there are thousands of species. The most common species we know in the vegetable garden is B. oleracea, which includes broccoli, cauliflower, kale, khol rabi to name a few. Brassicas are not self pollinating so if they go to seed they will cross pollinate with plants in the same species.

Check the species of your vegetables if you want to save seed and you’re worried about cross-pollination. Bear in mind that cross-pollination can happen within 400m of each other (so if you’re neighbour is planting something in the Cucurbita pepo species and you are too then cross-pollination can still happen.

So what’s better, hybrid or heirloom?

Hybrids are faster, stronger and usually produce better than heirloom plants. They are however a one trick pony. You will need to rebuy them every year which puts you out of pocket and fills the pockets of the giant seed companies. Though hybrid seeds produce plants that are disease resistant and can mass produce, this is often at the expense of taste and nutrients. An heirloom tomato will often have more flavour and vitamins than a hybrid.

The act of seed saving that heirloom produce allows is more than just saving money. It’s amazing to know you are growing the exact same plant that grew hundreds of years ago. Koanga Institue in New Zealand does some amazing work with keeping NZ heirloom varieties alive. Their selection is just awesome, so many delicious varieties. Buy one packet of seeds and you can grow and save seed forever!

Want to read a cool story?

A school in Canada found an 800-year-old squash a few years ago with preserved seeds! They have successfully grown a squash from these seeds and are now working on saving more seed to bring this squash variety back.

Ultimately the choice is yours but if you haven’t tried seed saving yet, I encourage you to give it a go! It’s extremely satisfying to be able to continue planting each year without the need to purchase more seed.

Happy gardening!

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