What is the best depth for a raised veggie garden, 6 or 12 inches? I'd like to plant tomato and peppers along with lettuce and herbs.
6 inches is fine if there is soil beneath the raised bed. If the raised bed will be on a non-soil surface, like concrete, I would recommend at least 12 inches.
My grandfather used eggshells and coffee grounds to fertilize his tomato plants. What would happen if I did the same thing today with my tomato plants?
These are great things to use to fertilize tomatoes. Eggshells provide calcium and coffee grounds provide nitrogen, which are both helpful to tomatoes and many other plants.
I have a new garden in north Florida. I transplanted tomatoes and two days later they started to wilt. I gave them a little plant food last night, and they look a little better this morning. They had a little water two days ago. Should I give them more water? My dirt has just been broke.
Water them about once a day for a week or so. They are trying to grow new roots and the extra water will help that. After a week, they should have enough roots to find water on their own.
They definitely need watering more often in the severe heat & temperatures we have in NE Fla. The 1st couple years of tomato growing here was struggle, primarily because I didn't water enough. Experience has been water twice per day with much peat mixed into the soil. I'm trying baby powder this year.
I live on Long Island, NY. Last year my garden had major problems with tomato blight, probably because of a very wet spring. I was never able to get the problem under control, but my garden did yield a decent amount of fruit anyways. I have read that blight can live in the soil and return the following year. Is there a way to treat the soil so that won't happen (I don't have any other place to plant, so crop rotation is not an option. )?
There really is not much in the way of fixes for blight that do not require the beds to either be rotated or left empty. Solarization can be done (https://www.gardeningknowhow.com/garden-how-to/projects/how-to-solarize-garden-beds-to-eliminate-garden-pests-in-the-soil.htm) but that has to happen during the sunniest time of the year, which is also your growing season.
Have you considered container gardening for a season to allow the beds to purge the blight? The containers could feasibly be placed right on top of the contaminated soil, as long as you took steps to make sure the soils did not cross contaminate. Here are some articles that may help you if you consider container gardening for a season:
https://www.gardeningknowhow.com/edible/vegetables/vgen/quick-guide-to-container-vegetable-gardening.htm
https://www.gardeningknowhow.com/special/containers/designing-your-container-vegetable-garden.htm
https://www.gardeningknowhow.com/special/containers/upside-down-gardening.htm
You may also want to look into only planting blight resistant varieties. This reduces the number of varieties you can choose from, but at least you would be able to grow your favorite vegetables without having to deal with the blight.
I am a beginner gardener. I would like to plant a vegetable garden as soon as possible. I like such vegetables as tomatoes, cucumbers, squash, carrots, etc. I need to know when (time wise) I should plant each thing and when to expect each to mature.
If you haven't done so already, check out our beginner's guide to vegetable gardening, which should provide you with everything you need to know about vegetable gardening: https://www.gardeningknowhow.com/edible/vegetables/vgen/starting-vegetable-gardens-guide.htm
Last year my tomatoes developed black spots on the leaves and from what I've read about all the possible diseases, they can stay in the soil. Is there anything I could do to get rid of it? Do I need to change the soil in the garden?
You can either rotate the tomatoes (and other nightshades like potatoes, peppers, and eggplants) out of that soil for a season or two and let the disease die, or your can solarize the soil to kill the disease. These are really your two best options for dealing with tomato bacteria and viruses. Here is some information on solarization:
https://www.gardeningknowhow.com/garden-how-to/projects/how-to-solarize-garden-beds-to-eliminate-garden-pests-in-the-soil.htm
Which tomatoes require cross pollination and which can be grown with just one plant?