Spring has sprung here in New England and the farmer's markets, farm stands, and greenhouses are displaying their wares. A friend just spent $200 in one day on plants -- all annuals! Yikes! Here are some tips to keep your garden costs low.
Plant swaps -- look in the newspaper or at the library or call your local gardener's association. This is a way to thin out unwanted or multiplied plants from your own garden and bring in some new ones. I have some lovely dead nettle that spreads like wildfire (or like dead nettle), ivy, hostas that multiply like crazy, and beautiful blue colombine. I thin out my patches of this and trade for veggie plants or whatever catches my fancy!
Charity plant sales -- if you can't get a plant for free, you can still get it for less than commercial nurseries want to charge.Look in the papers for fundraising plant sales -- especially from local gardening or botanical societies. You can usually buy the plant right from the grower and ask questions about care, etc. These plants always cost much less, are very healthy, and you're supporting a good cause.
All-perennials, all the time -- I used to find it so hard to remember that "annual" meant a plant only lived for one year. Maybe it's a slick marketing trick. :) Just get perennials for your garden. They are usually a one-time investment (although I do sometimes have perennials that fail to return over the winter), and they usually multiply, allowing you to cull your crop and bring the excess to plant swaps (see above). Non-food annuals seem like such a waste of time and effort to me. I guess i'm a lazy gardener, but I like to see my plants coming up each year without doing a whole lot of work, and without spending anything.
Go native -- Plants that are native to your location will do better than exotic non-native plants. You are less likely to have to replace native perennials than ones that have come from elsewhere. You can also likely find these on the side of the road, or in the woods (ferns, lilly of the valley, violets, etc.), where you can pick them if you know it won't harm the eco-system.
Plant food -- the only annuals I get are food-bearing plants: tomatoes, lettuce, squash, herbs, etc. Get these at swaps if you can (they're probably heirlooms, organic, etc.). If you're really frugal, or have a greenhouse (I live downtown and do all my gardening in containers), you can keep the seeds and grow your own heirlooms, too. The cost of one tomato plant at a charity sale is usually one or two dollars. So for an investment of less than $20.00, a person in New England can have a bountiful crop of veggies.
Craigslist -- Check the "Free" section on CL for plants. People often re-landscape and will give away plants to anyone who will come and dig them up. I've gotten (and swapped) great stuff here.
Free dirt -- If you need dirt (like I do in my container world), ask around of your friends with in-ground gardens. They will often share.
Containers -- I'm transitioning away from inexpensive and eco-friendly terra cotta pots, because they freeze, crack, and break over the winter. Even though I'm anti-plastic as a rule, I'm switching over to those lightweight styrene or plastic pots, because they last a long time. I have several that are ten+ years old. Also, be creative -- use old 5-gallon paint buckets (great for tomatoes), tin cans, or other non-breakable containers. Look for these at tag sales, too.
Compost -- our town gives away free compost, and one can certainly make one's own.