My broccoli heads have a black mold/mildew type of discoloration. What causes it, how can I prevent it and what can I do about it now that it's on my heads?
This is likely Sooty Mold.
You can treat with Neem Oil.
Here are some links to help you.
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm
What is causing my young broccoli leaves to be cut in a sharp, saw-like pattern? After an initial attack, the leaves have zig-zag patterns, with the upper part removed. The second attack takes the rest of the leaves down to the stalk. These are young plants, just transplanted into the earth, but I am also getting attacks in plants still in my starter trays. I have examined the leaves carefully and I do not observe any insects.
Cutworms are the likely pests and Broccoli is a favorite food of Cabbage Worms, Aphids and Flea Beetles.
Treat with Neem Oil and you may want to use a covering to help protect your young seedlings and plants.
Here are some links to help you.
https://www.gardeningknowhow.com/edible/vegetables/broccoli/common-broccoli-problems.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
How long after those first sprigs can I keep harvesting? Is there a time that I just pull the plant and start a new one? My broccoli don't seem to get much more than a stem of broccoli here and there. I live in Florida so it is hot here.
This article will help you. As the article suggests, you should be getting a second wind from your broccoli after harvesting the main head from side shoots. One sure fire way of knowing when to pull up broccoli is when it starts to bolt (when you see a hint of yellow, the florets are starting to bloom or bolt.)
https://www.gardeningknowhow.com/edible/vegetables/broccoli/harvest-broccoli.htm
Why does my broccoli have yellow blooms?
Your Broccoli has bolted and gone to seed.
Here is an article that has more information for you.
https://www.gardeningknowhow.com/edible/vegetables/broccoli/bolting-broccoli-growing-broccoli-in-hot-weather.htm
https://www.gardeningknowhow.com/edible/vegetables/broccoli/how-to-grow-broccoli.htm
I'm pretty sure that a rabbit got into my garden and ate the leaves off of my young broccoli plants as well as my cabbage plants. My question is...will I have to replant new plants in replace of these or is there a chance that something may still come from these plants? This is my first time planting either of these plants so I don't have a clue. Thank you.
I'm sorry your broccoli was a meal for a creature and not you! Yes, you could still very well get decent broccoli heads from your plants: depends on your weather conditions and how well you keep the rabbits (and other creatures) out going forward. Broccoli is a cold-weather crop, so if your weather is getting ready to get hot, you'll want to take some precautions.
These articles may help you:
https://www.gardeningknowhow.com/edible/vegetables/broccoli/how-to-grow-broccoli.htm
Good luck, and I hope you get to enjoy your fresh broccoli -- there's nothing like it, so if it doesn't work this year, definitely try again!
Once broccoli has bolted, can it still be harvested for food? What is best method for freezing?
Typically, unless you catch it in the very early stages, once a plant has bolted it won't produce anything edible.
These articles may help you:
There are several ways to freeze harvested vegetables, so which one is "best" is a matter of opinion. Here is one simple method:
http://nchfp.uga.edu/how/freeze/broccoli.html
Do I need to keep some kind of covering over my broccoli and cauliflower plants in the garden? I have decided to try broccoli and cauliflower in my garden this year. I got some plants, transplanted them to the garden, and now they are thriving. I was told recently that I need to keep these plants covered so that they do not get burnt by the sun. Would a sunscreen be appropriate to place over them so that they still get a little bit of sunlight but not too much? Or am I ok with just making sure that the leaves are pulled over the curds and florets? Thanks for any information you can give me!
It sounds like they have made a good transition to the garden. Hardening the plants off is a important step, but covering them now would not be necessary.
I have listed links with more information.
https://www.gardeningknowhow.com/edible/vegetables/cauliflower/growing-cauliflower.htm
https://www.gardeningknowhow.com/edible/vegetables/broccoli/how-to-grow-broccoli.htm