Yes, I know it’s not Sunday, but, when it comes to discussing annuals, why should we be confined to Sundays? Here’s my question. An annual is a plant that grows, blooms, goes to seed and dies in a year. A perennial is a plant that grows, blooms, goes to seed, and lives on for many years.
Now, a morning glory is technically an annual, because it grows, blooms, goes to seed, and dies all in a year. But once you have morning glories, who ever needs to replant them? They just reseed themselves nicely until the end of time (or so it seems).
So, how can a beginning gardener know which annuals are actually annuals that you will have to replant your damn self next year and which are annuals that, though they are dead, their children and their children’s children will live on in your garden until you kill them?
Tiny Cat Pants 
Google the term “self-seeding annuals” and you’ll have more info than you probably wanted.
This all is making me very excited about my garden. I wonder if I should plant my pansies now…
The internet is a good friend to gardeners.
Generally speaking, perennials have some sort of rhizome, tuber or bulb that lives on in the ground from year to year, and that can multiply.
Self-seeding annual one year = weed for ever after.
I am still, honestly, not sure what a rhizome is. It looks to me like a thin tuber or piece of root. But wikipedia says it’s some kind of stem. So, when a redwood falls and new redwoods spring out of its trunk is that a rhizome?
Ooo. Vol Abroad! I hope so. That’s my type of gardening! I’ll pick some plants I like and they can decide where in the yard they’ll live!
A lot of it is directly related to the seeds a given plant pumps out and if they are protected… For example, I have reseeding petunias, portulaca, marigolds, and morning glories… they are container grown, and when the seeds fall, they fall back into the pot. Voila! I also make sure to harvest seed pods too and maintain my own library so I can have free seeds for the next year.
Speaking of… if you want a big handful of marigold seeds (helps ward off some pests and they’re darn pretty), I’m your guy.
Rhizomes are like ginger or irises.
Jonathan, you don’t even want to know about all the marigolds I have for my yard already. It is my goal to make my yard utterly unfriendly to all yucky creatures. Did you see those holes in my yard?! I encourage the dog to pee in them.
How do you get reseeding marigolds? I even scatter the dried seed-heads of mine around and nothing comes up.
No kidding! And I read online that people get alyssum to reseed! I’ve never successfully gotten it to even flourish (but I’m going to try again this year).
I’d say a good rule of thumb is that if it’s an annual you see growing wild along the side of the road — morning glories, black-eyed susans, etc. — there’s a good chance it reseeds itself really well. Just keep your eyes open as you drive around and see what pops up naturally.
Most exotic species (petunias, impatients, etc.) don’t reseed well. I’ve had a few volunteer impatiens but not many.
I know this isn’t at all technical and has nothing to recommend it other than my old wifeness. It’s gardening advice along the lines of an old wives’ tale.
But my experience from a lifetime of gardening is that anything with profuse flowers does a good job of self-seeding.
If I had my way I’d just have self-seeding annuals everywhere. I started that type of garden but my neatfreak husband doesn’t find the wild tangle of bloominess very appealing. So the Morning Glories, Moonflowers, Four-O’Clocks, Bellflowers and Torenia all had to go. I’ve been able to keep one rosebush and the Wisteria.
Those also self-seed nicely.
It’s easier to get marigolds to self-seed if they’re in a container garden. That soil tends to be a bit softer than ground planting and therefore more accepting to marigold seeds.
I bet there are some climate things going on. In my experience, Morning Glories are terrible fussy things that barely even grow the first time much less reseed. Whereas Alyssum just reseeds itself no fuss at all.