Whether you have a small garden, a patch of land you grow on or rent an allotment there are ways and means of keeping the costs down. You may have to spend some money to save some but a bit of recycling can go a long way. Below I will list several methods I use personally to cut the cost of running my 10 perch allotment. These methods will require planning to make them work but are well worth the extra effort. When you are out and about be sure to have a look around any discount store and take advantage of end of season sales.
Scout around your community for stables, rabbit owners, farmers and chicken keepers. Offer them free removal of their animal waste and make sure you keep a good relationship going with them by offering them bits and pieces of what you have grown over time. Some people may just be content with you taking the manure off their hands. You may have to bag it up and transport it yourself so arm yourself with a shovel or scoop, some old animal feed or compost sacks and means to transport it, this can be your own vehicle or a garden trolley that you pull, whatever is feasible for your circumstances. You very likely will have to compost your collectings until they are well rotted before you can use them on the garden. I collect all the rabbit cage waste on my estate whilst I walk my dog, offering the owners the carrot and radish tops that my family do not eat when they are available and I am lucky enough to live close to two stable yards. If you live close to a busy town or city this option might not be so easy for you to take.
Plants need three major nutrients to grow, Nitrogen, Phosphates and Potash. You can get these nutrients from free sources. Nitrogen can be used in the form of grass clippings, phosphates and potash from comfrey. Nettles grow almost everywhere and comfrey grows wild or can be sown. There are several ways to use these as plant food, chuck in on the ground and fork it in or make a "tea" by soaking it in a bucket of water (weighing it down with a brick) and putting a cover on it for two weeks. By this time it will have fermented, will stink abit and will be perfectly good plant food. Don't forget to dilute it to one part solution by nine parts water before you use it or you may overfeed your plants and create a toxicity problem.
There are many receptacles that can be used as pots or planters, some are obvious and others take a bit of imagination. Recycling is the main theme. On my allotment all normal pots are washed and reused but i use a variety of other containers with holes drilled in. I use mushroom trays for growing spring onions in and for water trays, pot noodle pots, polystyrene cups, tires, crates, cooking pots, half pipes, and anything else i can find for putting plants in. I have plastic biscuit containers that act as propagators, baby formula cartons that hold dried seed. Ive even heard of someone who converted their old bath sink and toilet into planters and painted them to give them a surreal arty twist. Many of the people at the allotment collect big wooden crates from outside warehouses to make into raised planters for those unable to bend or work their plot. Don't forget empty soft drink bottles are useful as cloches for protecting young seedlings. I have also seen a whole greenhouse made out of recycled 2 lt cola bottles. Use a pencil to write on plastic or wooden plant markers so that you can rub the writing off ready for next years plants. To give my alliums a head start i planted them in compost filled toilet rolls on a tray until the weather was warm enough to plant out.
Heirloom Seeds and Seed Saving
Seed companies naturally want to make money out of you so they sell you hybrid seeds. This means you cannot for example grow a pepper then use the seeds out of it to grow more of the exact same plant next year as the seeds will either be infertile or will not produce the same plant. Not sure exactly how this works but it is the truth of it. If you purchase open pollinated REAL seed (non F1) and heirloom seed then providing you follow a few simple rules at the end of the growing season you can save seed from your own plants that you can sow the following year therefore never having to buy that variety of seed again. If i were to put a whole guide to seed saving in this space it would take far too long to finish this post. I personally purchase my seeds from www.realseeds.co.uk and they always come delivered with seed saving instructions. This does a take a good bit of extra work but can save me a good £70 a year on seeds. Another method i use to save money and get more plants is to use seed swapping sites with my saved seed, to plant varieties of fruit that need very little maintainance, take cuttings from your own plants to make more or swap seeds or produce for cuttings from your fellow gardeners.
Organic Pest Control
I personally, like James Wong's guide to pest control. It consists of two recipes. A garlic and chilli spray, that kills slugs, snails, flying insects, caterpillars and deters birds, mice and rabbits. It is as simple as blitzing up a lite of water with a bulb of garlic, chilli and marigold leaves, leaving to stand (the longer the better) and spraying on your plants in the evening. The second recipe is for mildew, mould and any fungal damping off. It consists of a litre of chamomile tea, marigold leaves and garlic all whizzed up together and brewed for a while.
If you are genuinely talented with your hands build what you must with scrap wood, recycled timber and as mentioned above, build a greenhouse out of plastic bottles. Those old shower curtains might convert into cloches. I have an old indoor rabbit hutch as a cold frame. These things don't have to look scruffy, with careful building and a lick of paint they can be dolled up nicely. When my old shed finally fell down it was cut up and made into smart 3ft high raised beds.
See the advice about fertilizer above, and then research how to make good compost. It probably sounds more complicated than it is but that little bit of extra effort goes a long way. I go through many sacks each year costing up to £5 each, but the better i get at composting the less I have to buy. There are a few things to consider about your own compost and they are to site it where it will not cause a nuisance, do not put seeds in it, keep diseased plants out and sterilize it using heat before you use it for germinating seeds. If you are on friendly terms with your neighbors they may give you their waste for composting if you ask nicely.
Containers and Storing Produce
Keep containers like butter tubs, etc jars, take away containers, baby formula boxes and tins for storing meals you have made and seeds you may have collected. Old furniture like sets of draws can be kept in a shed or out house for storing root veg in. Get a good book on food preservation and remember if it is done properly you can feed your family cheaper for a good while longer. We mostly make meals and freeze them and had to save up for a chest freezer to make it worth our while but there is always a healthy home cooked meal ready within 10 mins available.
Use old tights or stockings for flower bags and onion holders.
Make sure you store grown food properly and don't waste it.
Learning everything about what you are growing decreases the chance of loss.
Look out for or instigate veggie and seed swaps.
Use your grown food as currency with your fellow gardeners and neighbors (within reason obv)
keep an eye out for freebies online on face book selling pages, free cycle, craigslist etc.