Answer: When to plant depends on which vegetables you are growing. Some can be started early, before the last frost such as spinach, potatoes, and peas. Many are started about the last frost date. However tomatoes and peppers, squash and melons are very cold sensitive so are typically planted a week or two after the last frost.
The best soil amendment would be to add organic matter such as compost, well rotted autumn leaves, or well aged stable manure/bedding. You should also run some basic soil tests to see what kind of fertilizer is needed and whether or not you need to add lime.
As far as pests, it is difficult to give you specific advice without knowing which particular pest was bothering your plants. According to current pest control guidelines you would monitor the plants and if damage occurs, identify the specific pest and then if and when the damage becomes severe, treat for it. I would suggest you keep an eye on your plants and if you see damage, work with your local Cornell extension to identify the pest and determine how best to control it. Keep in mind that just because you had a certain problem last year does not necessarily mean it will happen again. Good luck with your vegetable garden this year!
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