a plant swap - what a great idea! i love how easily succulents propagate - they're so sturdy, even for people who don't have much of a green thumb like myself...

My 785sq/m garden is planted with 100% free plants. Every single plant was a cutting or a pull out from friends and my green thumbed mother. Succulents are the best for this process but orchids (especially crucifix or ground orchids) are brilliant for this process too. The only dosh I spent on my garden was my railway sleeper bed edges for $10 per 3m length. My $100 budget garden was heaps of fun and super easy to create... mind you it does help when you mother has an acre of dense rainforrest garden to pcik stuff out of. :P BUT I would also see pretty plants hanging out of peoples gardens and take a small clipping they wouldn't notice. :D

Garden club plant sales are good. (Cheaper than nurseries, a nice fundraiser for the club, and often varieties of plants hard to find anywhere else -- AND guaranteed suitable to your zone!)

End of season sales are good. Nurseries and Home Depot/Lowes garden centers (at least around here in the northeast) discount things up to 75% at the end of the planting season. (I like buying small trees that way!)

Craigslist is good. I wanted Siberian Irises, which spread nicely and therefore are a likely option for someone to want to share, so I checked Craigslist. I got bunches of them ready to bloom for a pittance. (Not free, sadly, but sometimes "free" happens there too...)

Apart from bulbs and cuttings from my in-law's garden, I've had terrific luck getting very cheap plants from retirement communities. A lot of residents in my area seem to keep a garden and share their bounty for pleasure--I find I often have to insist on paying them for their cuttings!

there are some great web communities such as davesgarden.com where you can get seeds, and sometimes cuttings by sending a self addressed and postage paid envelope to them. They also have forums where you can meet gardeners in your area or other areas and trade seeds or plants in person or by mail.

Also look for end of season seed sales, sure its optimal to use fresh seeds every year but some will still sprout next spring. Just expect lower germination rates. Starting from seed takes more patience and planning but can be really cheap too, just save containers to start them in - ive found berry containers work GREAT because of their drainage holes, just put them on a big tray or lid of some kind. '

I spent about $30 on seeds this year, and got about 250 plants out of it. obviously more than i needed, but seedlings make excellent gifts! Plus i now have crops of extras coming in (my deal is if i give you a seedling i get any extra veggies you dont need i get first dibs!)

Seeds are also a good way to go, you just have to be patient. For a $1 or so a pack you can get a garden full of different plants. Very slow process for perennials.... but definitely cheaper than buying the plants.

Ikea sells awesome indoor plants in many different varieties for very little green (*snicker*). They also sell amazing little modern white pots for $.99 a pop. My favorite source for my indoor garden needs.

Thrift stores are definitely a great source for vintage containers. Think out of the box by using old teapots, cups, buckets, etc.

don't dumpster dive at a nursery. besides the fact that yeah, it's stealing, the nursery might have thrown it away because it was diseased or infested with insects, which you would bring back to your own garden. also, asking for a discount on a sad looking plant is risky. if it's really been stressed and doesn't just have a cosmetic flaw, chances are it won't make it and you would have wasted your money.

I've found walking around your neighborhood and chatting up your neighbors is a good source as well. If you're on friendly terms or even just show enthusiasm, most gardeners are more than happy to snap off a cutting for you and give you lots of advice.

A source for free herbs are Vietnamese pho restaurants. I just grab the leftover sprigs of mint and basil and root them in water.

succulents, agaves, and cacti are my obsession.

Groupon and Living Social sometimes have coupons for local nurseries. As long as you do your homework to make sure the business is a good one, you can pick up a lot of plants for less money. If you want to try trees, they can get pretty expensive. Having a coupon would be really helpful and you support a local business.

I've been completely surprised by all the great plants I've seen on Craigslist! Herbs, veggies, flowers, trees, and shrubs; all for next to nothing, or even free.

shame on Amandad2 - never cut from someone else's place without asking! 99% of gardeners are happy to share if you pop a note in their mailbox. i give lots of plants to friends and neighbors as i edit & re-edit my tiny [13 x 17] yard, but I'd take after someone with a shovel if they just helped themself to my hard work and i was nearby!

I'll have to agree with @YEAH, I ANSWER TO RED ... "snipping" a cutting from someone's garden without asking permission is very low class. @Amandad2 you should be ashamed of yourself rather than patting yourself on the back for "being frugal".

I've been taking strays I like from the backyard and popping them in the front. Purple Heart can just be snipped and popped in the ground, which is probably why so many of my neighbors like to landscape with it.

Can anybody tell me the name of the round succulents on the left side of the photo?

@Pammyfay, those seem like hens and chicks to me (yeah, that's the popular name - hens and chicks). Go to Google and type HENS AND CHICKS PLANTS and once you get results, click the Images link on the left side.
Any garden centre will have a variety of hens and chicks.

@PAMMYFAY - I believe those are called chickens and hens

I'm lucky enough to have a fairly green thumb and I have "brought back to life" many plants that I found on clearance looking miserable or that friends/family had planted in an unhappy spot, so I totally concur on the clearance/dumpster diving!
Growing things from seed is also a good, cheap way to go and lots of things sprout pretty easily.
It is all about resourcefulness - Think about what you need and then think about who might see that as a scrap/waste product or who may have some to share. I'm working on getting wood chips from a tree service (yes, it may contain some bugs/disease, but for free, I am willing to gamble) and compost from a horse farm for much cheaper than the nursery. I'm also working on getting a neighborhood scrapper to take down a chain link fence for free in exchange for him taking the metal to cash it in.
Finally, if you're really brave and want a free fertilizer - it may sound gross, but there are several studies out that human urine (diluted) is as effective a fertilizer as storebought. (don't worry - urine is sterile as opposed to bacteria-filled solid waste) It isn't for everyone, but if you want to reduce wastewater and have an endless supply of free fertilizer, it is something to think about.
http://www.scientificamerican.com/article.cfm?id=human-urine-is-an-effective-fertilizer

Hilarious! I read a post and was about to post a followup that it sounded just like ME -- then noticed it WAS me, two years ago!!!

I still have the Chinese Evergreen I rescued for a dollar from a grocery store 17 years ago. Poor thing had mealy bug. Easy enough to cure with rubbing alcohol and a cotton swab. I just planted it's great-grandaughter, which rooted from a top cutting in a vase of water. :)

Thank you, Canadianmango and Threesquare!

I have a good sized succulent garden that I created using 99% FREE cuttings from a gardening group I found online. Check out gardenweb.com for local groups.
As Cathycolson pointed out, you should also check out craigslist for free give aways. Whenever I am thinning out my garden, I put a notice on Craigslist and just leave the cuttings in the car port. I'd rather give the plants a shot at life elsewhere than throw them away.

Check to see if there is a native plant society in your area. The one near me, has regular outings where they go to construction sites (with permission of course!) before they are bulldozed, to save any native plant species. Not only are native plants more likely to survive, they're more than likely not invasive either.

Honestly? I go to Home Depot and Lowes... and if those plants are sad, I go to a local hardware store for plants or a local grocery store. Nurseries are a bit of a rip off for planting simple stuff like ivy or pansies/petunias. If you want something special or need help figuring out what to plant where/when, then I'd invest in going to a nursery.