The Bayer Matirx contains contains twice as many green pixels as either red or blue. Debayering will end up giving you a very green image (I get this when I use astro software to debayer raw DSLR frames, nothing wrong with the camera or the software)
You need to adjust the white balance of the image. Based just on the above, you'd think you need to multiply the red and blue channels by 2, but I've never found it to work out as simple as that, you'll need to experiment, so I suggest getting it close with images of things you're used to, like an image of your garden, once you have the balance roughly right then you can apply it to the astro images.