To me the most complicated aspect of gardening seems to be the timing.. knowing when to plant what and where.
Not really complicated. It varies by zone, of course (I'm in Southern Colorado) but here's a few simple guidelines:
Late fall or early spring, October 15 until say April 15: onions and garlic go in. You can plant them as soon as you can work the ground.
Early plants such as sweet peas, lettuce, any cabbage family plant and a few others need to go in by April 15, earlier if possible. A freeze won't generally hurt these plants.
The rest of the garden should go in when the ground temps reach about 55 degrees, around here about May 5th or so. I've held off until Memorial Day with good results. This is the time to plant pepper and tomato plants and seeds for all your bean, flower, cucumbers, squash and melon plants. Remember this though; when planting tomato plants, bury about 80% of the plant. Tomatoes will grow roots wherever the stem touches soil. At this point, you are going for strong root systems. The top growth will come soon enough.
If you plant sweet corn, plant a batch every ten days from around May 5th up until July 4th if you want that much. This will keep you in fresh corn from around July 20th clear into October.
Some plants, like carrots ad radishes, can be planted anytime from spring until mid-summer. They make a good follow up crop after your early spring plants are gone.
edited because I can't type
