Could it be that it is getting too hot already? My Swiss chard does really well with the reasonable temperatures, but when it gets above 85 it seems to quit growing. Have you gotten that hot already?
If you cut the leaves off, that might encourage her to keep growing. it Does replenish itself well.
re: stunted chard
We had one hot spell, and it has been mild for a couple weeks now. I’ll try cutting the leaves off. Thanks.