Okay, let me ask a question here. You say SOUTH FACING HOUSE. Which means, the house front entry is facing south.

If the front entry is south, where exactly is your garden?

Let's suppose that your front door does face south.
Your garden is at the BACK of your property. So that means it is on the NORTH SIDE of your house, opposite the south facing front door. So out your back door, you are looking NORTH>

Well, what gardening zone are you in? If you are way up north, those trees will block the north winds. They will NOT block any sunlight. Except beneath the trees perhaps.

When the sun gets as high in the sky as it is going, that is the longest day of the year. From that point, the days get shorter as the sun falls back toward the south. With this arrangement, you will get lots of sun in the winter and full sun in the summer as well.....providing you have no trees in the remaining yard space.

If your garden is not in back of your house, then tell us whereabouts on your lot is it.