Carnivorous Plants/Temperate sundew
I live in Redding CT and grow my temperate plants outside on a porch which gets 5 hours of direct sun a day. They are sitting in about 2 inches of sitting water. I recently got a drosera binata and a drosera Tracyi, they both were not doing too good outside, even though my sarracenia and Flytraps were doing fine. I know some people grow their temperate sundews in terrariums and I am asking if it is fine to grow the temperate sundews in the terrarium and give them a dormancy in the garage during winter. Thankyou!
Like most things the devil is in the details on a subject like this. You actually have quite a few variables going on here, and if you just "broad-brush" the approach, "Others grow their temperate sundews in terrariums"; trouble lies down that road.
Let's take the two sundews you have for starters. Drosera binata is not just one plant. There's many different sub-varieties of this plant, and some are temperate, but some are more tropical. D. binata multifida tends to be tropical, yet D. binata dichotoma and D. binata T-form are more temperate. D. dichotoma I've had ok luck with indoors, but they still will exhibit a dormancy in mid-winter. The smaller binata forms tend to need a colder dormancy since they often originate from New Zealand or Tasmania.
D. trayci is a North American plant originating from the Florida panhandle. They are distinctly a temperate plant forming winter resting buds. They tend to be somewhat tender in colder climates, but still need cool winters. They also need strong sun in the summer both because of their shape, and what their native habitat is like. Here in Oregon they tend not to produce their best foliage until later in the summer, often coinciding with the nicer pitchers of Sarracenia leucophylla, which they grow side by side with in their native range.
Here's my recommendations. Leave the sundews outside for now. Your temperatures have not been all that warm yet, but as we get warmer summer temperatures your plants are likely to start doing better. Protect them some from heavy rain. That tends to make them not look good. Also, you said you recently got these plants. You just may need more time with them to let them adapt to your particular conditions. As I mentioned above D. trayci often doesn't look good in cooler climates until later in the summer.
If you have one of the more tropical forms of D. binata that might make an ok terrarium specimen, but I don't really know what you had in mind for a terrrarium. Setting up a terrarium is a long discussion beyond the scope of this format. Drosera trayci makes a poor terrarium plant because of it's size/shape and light requirements.