Aphids

I rarely get them...cosmos wont last through the winter so i would bin. They are easy to start in Spring.

Keep it well ventilated, fast sappy growth encourages aphids - so you want your plants to grow slow. Jeeping the doors open keeps the temps down. I used those fly papers

I have had huge issues with fungus gnats - so ensure you water from the bottoms to encourage a dry top on your compost.

Keep any compost bags as dry as you can - I'm sure lots of my fungus gnat issues came in with soaking wet compost from the shop.