Washington, a Scots-born voice coach to celebrities including Penelope Cruz and Jessica Chastain, died in September last year at the age of 74.
Swazi-English actor Grant, known for films including Withnail And I and Can You Ever Forgive Me?, posted a video on Twitter showing him sitting in a sunny garden and reminiscing about the time the couple spent together.
The 65-year-old says: “Unexpected day off filming. Scrambled out to the Cotswolds to the cottage that my wife and I spent the last few months of her life in.
“Although it’s obviously emotional being here, it’s incredibly calm and restorative, surrounded by all the seeds that we planted together, which have just grown like mad this glorious summer.
“Grateful for the 38 years we had together.”
Turning to look at the camera and smiling, he adds: “Have a great weekend.”
When Grant announced the news of Washington’s death, he posted a video on Twitter showing them dancing to Only You by The Platters.
He wrote: “ONLY YOU! Joan – Love of my Life & Giver of Life to our daughter Olivia.
“Our hearts are broken with the loss of your Life last night. 35 years married & 38 together.
“To be truly known and seen by you, is your immeasurable gift. Do not forget us, sweet Monkee-mine.”
Grant married Washington in 1986 and they had a daughter, Olivia. Washington also had a son, Tom, from a previous relationship.
Although Grant did not give a cause of death in his initial announcement, he later confirmed his wife had died of lung cancer.
Washington, from Aberdeen, trained at the Central School of Speech and Drama and had nearly 40 years’ experience in the film industry as a voice and dialect coach, working with stars including Anne Hathaway, Vanessa Redgrave and Emma Stone.
Among her early projects in the mid-1980s were Yentl, starring Barbra Streisand, Highlander, and The Bounty, featuring Mel Gibson and Sir Anthony Hopkins.
More recently, she worked on features such as The Witches, where she coached Hathaway for the part of the Grand High Witch, and Yorgos Lanthimos’s black comedy The Favourite, where she worked with Stone.