First things first, know what growing zone you are in. It isn't going to be a date set in stone as mother nature loves to throw a few curve balls for last frost/ first freeze, but it will give you a rough idea to work with. Soil temperature is going to be a more accurate guideline overall as to when to plant, knowing what zone you are in will give you an idea when to start transplants.
Speaking of soil, it is always going to be a work in progress. You can have it tested to give you an idea of what may be lacking, what ph it is, etc. If testing isn't feasible, no worries. Here is a rough generalization of amendments to consider: compost compost compost!
- if you have clay, one of the easiest amendments is going to be compost. It will help give loft, improve drainage and add nutrients. Clay tends to contain a good amount of trace minerals, what ones and how much really depends on your location.
- if you have sandy soil, again you want to add compost. Sandy soils are quick draining and usually lacking in nutrients. Compost in this case will help retain moisture.
Shoestring budget doesn't mean you can't have a Victory garden, it just means creativity and resourcefulness is going to be your greatest attribute. If purchasing truckloads of finished compost isn't an option, look for alternative local sources as well as make your own! Call up local stables, check at feed lots for sources (that tip courtesy of Terry), hit up the local Starbucks (grounds for gardens. Sometimes they need to be reminded of this program they offer and often it may take a bit of time to get them into the routine to save grounds for you. The payoff is those grounds can be turned right in to the soil. They will act as a mild nitrogen source as it contains only about 2% nitrogen, of which only a fraction is readily available and the rest is slowly released as it breaks down in the garden.). No Starbucks? Then try calling and asking other locations like restaurants as some are willing to help if you provide a suitable lidded container. Check with your local town as some have free compost and mulch for their residents. Look to your kitchen and yard as well for materials to be composted.
If you decide to create your own compost you should know what is good and what should not be added as well as how you want to compost. The whole composting issue is for another day, let's just leave it for now as I can't ever get enough of it!
Don't get swindled by the hype. Gardening is one of those activities where the more you know, the more you can save. Some of it may take effort, or staying on top of things, some of it is as simple as knowing what container works best for saving seeds.
What plants to grow... what plants to grow? Big box stores will have transplants of a few varieties that are supposed to be a good cultivar to your area (ideally). My only issue with them really is that more often than not the ones I see are root bound, infested with various pests, or also are sporting diseases. Usually I see better options at the smaller nurseries, but still you need to keep an eye out.
Seeds. Gardening is a lot of trial and error. Some plants offer more per growing area than others. Beans for example not only offer a pretty good sized crop for the amount of space they use, but they also add nitrogen back into the dirt as well as good material for the compost once they are finished. Go for as much variety of different kinds of crops as you can. Although hybrid varieties tend to be created more for productivity, disease resistance and the like... heirlooms also have their endearing qualities.
Buying seeds can get really pricey if enthusiasm gets the better of you. Try to look at it more like taking care of an investment. Some sell mini packets and then for a little more $ sometimes the next larger size can have twice the amount. Some seeds like parsnips and onions don't retain viability very long, but then you have others like tomatoes, beets, peppers, etc. that if stored correctly can hold their germination for quite a few years. The key.. storing them in an air tight container with desiccant, out of light, and in an area where the temperature is consistent.
OP (open pollinated) and heirloom seeds are like the gifts that keep giving. Some need a bit of work to make sure they do not cross, but those efforts can pay you back significantly in the end. Here's an example, I bought a packet of dill for $3, roughly 300 seeds. Planted in late spring (2 successive plantings) I let half go to seed to be saved for later plantings (the other half of the seed heads were snapped up by a neighbor for pickles). The amount of seeds I have from that for later plantings... well let's just say I am set for the next 5 years even if I don't save any more.
There is an amazing book out on saving seeds. It is called "Seed to Seed" by Suzanne Ashworth. If not in your budget to get this seed saving bible, pester your library to get a copy. Just take it in small steps when you do read it as it can seem overwhelming otherwise.
There are other sources as well, not that I recommend them necessarily, but I find it entertaining to experiment. I have saved seeds from particularly tasty tomatoes and peppers I got at farmer's markets. I've planted cloves of garlic that were from the store. Potatoes same thing, except I find they usually have issues like scab which can take a few years to eliminate from the soil. Bunches of basil.. tossed them in water and they rooted. Repotted them and collected several more cutting before letting them go to seed and collecting those as well. Winter squash is kind of tricky, butternuts I have had luck with seeds from those out of farmer's market purchases, also had luck with hubbards. Spaghetti, acorn and pumpkin (all C. Pepo)... not so lucky. Squash flowers produce a ton of pollen so it will make any bee a raging floozy.
Well enough rambling for today. I have more seeds to start and compost to turn before the family wanders home with outlandish demands... like feed me.