I have dreadful soil, and as a result gardening is a bit of work. I have to till, amend, weed, compost, hope and pray a lot. Some crops, like corn, are
always iffy and I fight every year to get a decent crop. Others, like peas and beans, will give me far more than I can possibly use. This year, I have another potential "overabundance" in that my zucchini, which did not come up AT ALL last year, has come up fiercely this year...so I may feed the world from it. While I've been doing *some* gardening for the past 20 years or so, this is the first time I've really had a multi-year thing...so here are the mistakes I'll try to not make again.
Mistake #1. Buying vegetable plants instead of seeds.
An exotic tomato plant can cost $20. If you're like me, you want about 10 cherry tomato plants and 10 other tomato plants to feed your family and have enough to give neighbors and put up for the year. Let's assume you've found a good deal on tomato plants- 4/$10. Assuming you're willing to put up with the limited selection of varieties offered locally, you're looking at $50 just for tomatoes. This year, I spent about $350 on a
light cart, surge protector with timer, small fans, extra bulbs, reusable seed starting kits, peat pots, extra soil, fertilizer and other stuff for staring seeds. At the end of the season, with the light cart put away, I'm down about $30 in fertilizer and soil, and all the other stuff can be reused. (although I purchased two different types of seed starter kits, and will probably purchase two new ones next year- I was *very* hard on them, reusing them 5 times already.) I purchased about $15 worth of seeds for EXOTIC tomatoes and peppers, plus received free seeds from friends, and now have about 30 tomato plants growing, ranging in color from Black Truffle (a deep purple) to White Wax (a nearly true white) as well as red, white and yellow cherry tomatoes in a deck planter and yellow and dark brown-green peppers. I also started zucchini, corn, squash and pumpkins from seed... Next year, with saved seeds, refreshed soil and new seed starter cells (which I don't
need, but do
want) I'm looking at less than $10 in tomato and pepper seeds....making the seeds+soil still $10 cheaper than the crappy on-sale tomatoes.
Mistake #2: Not buying a
soil testing kit.
One of my neighbors down the street has the formula for the "perfect lawn." She mixes sand and lime with grass seed, and covers bald spots with it. It's worked perfectly everywhere but here... So, she keeps trying, assuming the birds are carrying the seeds away.
We essentially

have the same dirt... so what is she doing wrong?
My soil has a pH of 8.5. In some places, this goes up to 9. In others it goes down to about 7.8. Lime *raises* the pH of the soil...she'd essentially trying to grow grass in baking soda...no wonder it does so poorly!
Worse yet, my soil is claypan-like in the example shown to the left. It looks lush and lovely, but during periods of drought it becom

es cracked, dry and all around gross, like in this image to the right. It consists of approximately 5 inches (1 in some places) of top soil and 10 inches of clay, which prevents drainage in the spring, and can turn into essentially brick if not kept moist in the summer. (we live in a moist area, and we sprinkle, so it works out.) Like most clay soils, it is high in lots of good minerals for growing things, like calcium, phosphorus and magnesium. Like most clay soils, however, it has no nitrogen, and is a very high pH.... it's "alkaline as hell."
Do you want to know what else my neighbor is doing wrong? Do you know what you get when you combine alkaline soil with lime and sand?
You get CEMENT. Oops. [Click pics to see original sources for these pics.]
Mistake #3. Failure to Identify the local weeds.
Another idiot neighbor has a weed in her yard that she mows down weekly. This only seems to piss it off. A third neighbor says that he tills all the weeds at the beginning of the year...but some of them keep coming back... A forth says she'll *never* use a weed killer.
Our local invasive weed is Japanese Knotweed. It spreads when the roots or stems are disturbed and chopped into little pieces. I, another person who said she'd *never* use chemicals on her lawn, manage mine by injection of round-up and archaeological-type digging, removing every bit of plant matter over a quarter of an inch long from the soil.... and my knotweed is getting to be a little less problematic every year. If I'd followed the advice to mow or till it I would've made my problems WORSE.
Mistake #4. Too many annuals.
This year my garden will produce strawberries, raspberries, apples, mulberries, gooseberries, blackberries, wineberries and currants that I did not plant this year. It has already produced rhubarb, and will have peaches, plums and apricots in the future.... The answer? Dwarf fruit trees and perrenial bushes. No work...lots of food. Plus, I get the exotics, like gooseberries, which I can't buy in a store. I also have arctic kiwis (too young to bear) and grapes to look forward to in the future.
Mistake #5. Putting plants out too early or starting them from seed too early.
I'd lecture on this, but I do it every year....so I'd be a hypocrite.