Q.Why Has My Greenhouse Grown Chard Gotten Tough And Hard?
Second question Do I need to empty out the soil used in my greenhouse this summer, before planting seeds for my winter veggies? Third question I’m in Fairfield, Iowa. When do I start seeds for winter chard, etc., and what veggies can I grow in my greenhouse this winter in addition to chard? Thanks!

Certified GKH Gardening Expert
Likely, it is the heat, or has gone over ripe. Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-5/zone-5-vegetable-gardens.htm
https://www.gardeningknowhow.com/edible/vegetables/swiss-chard/swiss-chard-diseases-and-pests.htm
https://www.gardeningknowhow.com/edible/vegetables/swiss-chard/swiss-chard-spring-planting.htm
https://www.gardeningknowhow.com/edible/vegetables/swiss-chard/how-to-grow-swiss-chard.htm