Nothing keeps it from happening. We don't know for sure that the seeds will come true. How true they come each year varies by species. Tomatoes tend to be very stable while something like daylilies is highly variable.

Can get some cool surprises too LOL!
In 2006 I saved seeds from my annual burgundy and lavender Scabiosa; sowed the seed for 2007 and got a few white blooming ones from the lot! That was way cool and I hope the many folks that got seeds from these this year will get a few too :D

Vera

Yep, like Vera, I do so enjoy the surprises.

A couple of years ago I received seeds in a trade marked 'Unknown Perennial Purple Geranium'. When they flowered, the result was an Orion and a Splish Splash, both of which I had admired in a friend's garden the previous year. Bonus!

Splish Splash.
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Orion.
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I'm resurrecting an old thread that I started last year about this.

Karen

Here is a link that might be useful: You never know what you're gonna get

So I suppose that nurseries start with true seed and then grow them in greenhouses where nothing can cross pollinate them?

And I guess if we trade for a certain plant and think that we are planting out that particular color we may get a surprise?

proudgm: Think of it this way.

A nursery starts a plant, say a rudbeckia hirta named Becky, from "true seed". You buy said plant named Becky and plant her in your garden. Becky is pollinated by the birds and bees who visit all the flowers in your neighborhood, including the gloriosa daisies grown by the Jonses and the rudbeckia Irish Eyes grown by the Smiths. You save the seeds that Becky produces, and you germinate and grow them the following year.

Becky's babies might look just like her. Or they might look like the Jonses gloriosa daisies, or the Smith's Irish Eyes. Or, maybe those babies will look completely different, like their great-great grandfather from Tenessee.

Get it? Think of your own family. You might have your mom's eyes but your Dad's nose, mouth and jaw line. But even if you and your parents all have brown hair, that doesn't mean that your own kids can't have red hair. Wait! Your husband isn't a redhead!!!

That's true, but your dad's mom is a redhead, and so are 2 of his sisters.... it's much the same for plants and their relatives. I can't explain nor understand all the science behind dominant and recessive genes, traits that skip and generation, etc., but that isn't necessary. All you have to know is that many plant species will cross polinate, and the results can be varied and pretty.

Karen

I'm not worried about my flowers being different. I know they will all be pretty even with variations. I was just wondering how nurseries can grow thousands of the same plant and they all turn out to look like they're supposed to.

I'm not sure how nurseries do it but I'd guess they hand pollinate.

If I want to increase the liklihood that a plant will be true to type, I buy some fresh seeds. Even this isn't a guarantee, but increases the liklihood. Such a plant for me this year is Rud Prarie Sun. I bought a pack of new seeds. I'm also trying to germinate some of my own harvested seeds, just to compare the results. Experimenting is fun!

Karen