The best thing about growing plants in the greenhouse is there are NO WEEDS or slugs. Insects, yes sometimes, and it can be a bit difficult to control the temperature and get the watering right, but there are no weeds or slugs!
I've hung up two non-toxic sticky strips to catch insects. They worked in the house to catch flies. After half a day they had traped about half a dozen assorted insects. Now I'm worried they are catching those which would eat the pests. Trial and error, more luck than judgement!
I wouldn't claim we have grown enormous crops or prize specimens but we have always managed to get a decent harvest from our greenhouse. A few years ago we were so successful with the hot chillies that once dried they kept us supplied for nearly two years (and the Webmaster never cooks anything, or even makes cheese sandwiches, without them. Combined with the late season green tomatoes the fresh ones also made an excellent chutney. Unfortunately it was a recipe made up on the day by the Webmaster (he's a secret chef!) and it is unlikely he will be able to reproduce it again, but we are ever hopeful for something equally as delicious.
Our main greenhouse crops this year are, as usual, tomatoes, hot chillies and mixed sweet peppers. For the first time we are also trying to grow aubergines. The plants are looking good so far, so fingers crossed they will flower and fruit. The butternut and patty pan squashes which we germinated in doors and brought on in the greenhouse are now planted out and the battle with slugs and insects has begun, as are several of the herbs. We rather overdid the herbs still have many seedlings to be planted out. I'm thinking of converting an old iron bath which used to be used as a water trough for horses into a herb garden feature (but don't tell the Webmaster yet!)