Put foot on stairs (or a block of wood would do) and drop heel down – NOT really a stretch but strengthening and revising the plantar fascia has good effect on plantar fasciitis
Stubborn heel pain & Treatment of plantar fasciitis using high-load strength training
Robert Caratun MSc et al
Canadian Family Physician 64, no. 1 (2018): 44-46.
https://www.cfp.ca/content/cfp/64/1/44.full.pdf
Important step is use of rolled up T-shirt to help with stretch:
Bring feet/foot up and slowly bring down for 5 secc. – requires use of stars and can be done bilaterally at once – 5 sec holds – NOT a Stretch (that would be uncomfortable)
Stat off once daily repeated ten times and work up. After a month add weights by use of coat or backpack.
“it is important that patients are compliant with the training paradigm and have some tolerance for pain.”