Hello Anneliese,
I'm really sorry to hear about your knee problems, but I hope you'll overcome the problems enough to tend to your garden/greenhouse at least in a limited way. 150 plants, wow. I consider myself a "big tomato grower" (at least compared to the gardeners around me), but I only had 55 plants. And I am sure much fewer would give me the same level of happiness. Yes, the numbers are due to our curiosity, but the more important feeling is when you watch them growing well and you know you've given them what they need. So I count on reduced numbers when my strength or health are failing, but I won't give up till I die.
I wish you a good recovery.
Milan HP