Ask Mr. Smarty Plants

You have some work ahead of you but you are on the right track. With numerous plants to care for, and by the sound of it, these are fairly young, we will talk about the basics for winter care and then go into scenarios that might help you with some specific issues.

You have the right idea by using cloth to cover your plants. This allows air to the plants which is crucial to their health and happiness. However wrapping the plants directly is not the best way to protect them. You don't want the cloth to freeze to the plant foliage. Visualize sticking your tongue to a frozen flagpole. You can prevent this by wrapping the cloth around stakes placed around the plant in a circle, triangle or box formation. You can leave the stakes up for the winter and only remove the cloth when the temperature moderates. You do have to remove the cloth when the the temperature raises, usually at daylight. You could perhaps compromise and wrap the sides of the stakes, leave them in place and just have cloth covers at the top that you remove daily. This would allow for gentle temperature increase, light to enter, and easy access to rain.

Not to get too crafty but for a cheaper version of your idea for the drawstring bags, you could get your hands on some big burlap bags that have drawstrings. You could cut out the bottoms, slip the bags over the stakes, then loosen the tops in the morning and let the bags fall to the ground for the day. At night (ideally before the sun goes down) pull up the bags and tighten the strings. Of course this would only work for medium sized bushes and perennials. Local feed stores have great big ones. You could ask them if you could have the used ones that they would be tossing out. Some are made of plastic but because that plastic is woven, still allowing air through, they would work just fine. 

As we don't know all of the varieties or sizes of plants you are caring for, here are a couple of tips that address a variety of cold weather problems: 

Newly planted thin barked trees are some of the most vulnerable in a cold snap. In Florida where you have intense sun, the radiant warmth the sun produces during the day can cause sap to flow. This heating and freezing combination can cause splits and cracks in limbs and trunks, which opens the trees up to fungal infections as well as sun scalding. To help protect your new trees, wrap their trunks with Tree Wrap. A product made of corrugated paper. Wrap the trunks from the base of the trees up to the first layer of branches. Tie or tape the top. Don't be stingy on the wrap, you want them to be tucked in. This you can leave up until early spring. It isn't a bad idea to do this every winter until you see the trunk bark thicken and become rougher with age. 

Another care option to perhaps add to any broad leaf evergreen that is too large to cover, would be to use an Antidesiccant spray on the leaves. This protects the plant with a thin layer of wax or resin depending on the brand. You have to reapply it every now and then. Follow the instructions on the label.

Water the ground before a freeze and do this before nightfall for two reasons. Freezing weather dehydrates the air and the soil. Watering gives the plants the extra moisture they need. This also will warm up the air around your plants as the water evaporates, keeping it warmer at night when the temperature falls.

With very young perennials or annuals this freezing and thawing can actually heave up small root systems. The soil contracts and expands with the rise and fall of temperature an in effect, this digs up your newly planted plants. To keep the plant roots from being jostled by temperature change, provide a layer of mulch. This will help keep the temperature steady and weigh down the dirt.

We know this all sounds like a ton of work but once you have a system down it is worth the effort. Many people relax their gardening efforts in the winter. However if you look around your yard, you will see a lot of activity in winter. So take a tip from the squirrels in your yard and get to work. The work you put it now will pay off next spring and hopefully keep your new additions warm as toast.