Tomatoes
Tomatoes are a great all around plant to have growing in your greenhouse and although they can be tricky to grow they are a necessity to be able to grow.
Kale
Kale is great for cold or damp areas and is an essential to have inside your greenhouse because its a good thing to have in your diet.
Cilantro
Cilantro is a wonderful herb to have in a greenhouse because its easy to manage and is a two-for-one plant because the leaves work great in recipes and the seeds can be used for spices.