After my vegetable garden goes dormant, do I need to yank out plants and start over with new plants, seeds, etc. I have cucumbers cherry tomatoes zucchini and peppers.
Yes you should pull out all plants/roots. Most vegey plants are annuals and die in late fall. They say tomatoes are perennial but I've never lived where there are no real winters. Really need you to tell us where you live, is this a deck garden in pots or is this in a specific vegetable garden?
If you have a garden outside, one of the things you need to think about is rotation. You won't be growing the same genus (ie. Solanaceae; tomatoes, potatoes, peppers) in the same space next season as you did this year. It would ensure any disease that was present or disease you were not able to see symptoms to be inoculated into the soil and passed to your next crop. In a year or two you will be able to grow tomatoes where you grew peppers, tomatoes or potatoes again. Next year you have to use a bed where you grew cucumbers or salad greens this recent growing season. Where you grew cucumbers will be a good place to grow tomatoes next year for example.
This picture is the beginning of our latest greenhouse that next year will be heated. Heated not so much to grow stuff for winter but to protect plants from the frequent freezes we have all summer long. Notice the raised beds and their 'gutters or trenches'. This soil is pumice, like sand and I've been incorporating decomposed organic matter for 4 seasons. The trenches will be cleaned out after pulling all plant material, the soil tossed up on the beds. Then we'll be mulching with bagged organic decomposed matter thickly 2" for winter. Some of the beds we'll be planting a 'cover crop' that is turned into the soil early spring.
My tomatoes are mostly in 5-7 gallon pots, my peppers in the foreground are in 1 gallon pots. (I used those tomato cages to give my peas some structure). This makes it easier to rotate crops and not use up garden space. Without a heated greenhouse we drag these pots into our little heated greenhouse to protect from freezing. All my vegetables are started from seed. It seems that every time I use 'starts' from outside sources I bring disease and insects into the environment.
All of those pots are filled with great potting soil, not the garden soil! Ornamental plants in the landscape, I allow to dry up and stay until the early spring before removing dead plant material. But vegetables, mostly annuals, are pulled and decomposed in a separate spot away from the garden in fall or as soon as the plant is dead or dying. The less contact of a vegetable in the soil the better and I'll have more confidence to plant the same genus the second year or the year after the next season in the same bed.
I will NOT use the potting soil in these pots again. They will be washed in diluted bleach and water before using again. I will use the old soil in my composts or in newer beds that need more organic matter where I know I will not be planting the same genus I grew in that potting soil. In the picture the farthest bed contains tomatoes, the next bed coming closer, are potatoes. Neither potatoes or peppers or tomatoes will be grown next year in either of those beds.
I've got perennials that will not be pulled up; strawberries (although I am pushing the limit as this is the 3rd year), asparagus, fennel, artichokes couldn't over winter, thyme, oregano, rhubarb, raspberries, blue berries, pockets of flowers (to attract pollinators), boysenberries...these I will prune in early spring. Dead foliage helps with insulating during the winter.
This rotation stuff is important. You do not want to learn the hard way like I had to when you get a beautiful crop (3 rows 25' long, 3' wide, tomatoes forming a hedge 4' high to find a few black spots and 2 days later all tomatoes, fruit, leaves, stems are black. Not funny! Once a plant has this fungus there is nothing that can save the crop. All the lovely tomatoes were wasted. Harvesting them did not work. The fungus continued and the tomatoes turned black.
Clean out the old, dead plant material and roots. Then mulch or cover crop your beds for the next season with new plants (growing from seed is ideal as you are a bit more in control)...use NON-GMO seed. The label NON-GMO has to be on the seed packet before purchasing. I order my seed in the winter from Territorial Seed. I get my seed potatoes from Potato Gardens in Colorado. Gathering and using seed produced by your own plants is very risky with a lot of unknowns. To include your plants might have been pollinated by GMO crops growing nearby. Is this your first vegey garden? Michael Dirr or Shane Smith have incredible books on growing vegetables.
Generally speaking, you have to remove most old vegetable plants at the end of the growing season. I grow tomatoes, zucchini, peppers etc and as the weather starts getting cooler, these plants start to die (or freeze) and I end up removing them from the soil and grow other winter resistant stuff (carrots, kale, etc.). Then at the beginning of the next growing season (typically spring), I start all over again with seeds or plants I buy from outside.