Question: Irises is part of a series of paintings that Van Gogh completed while he was an inpatient at asylum during what period?

Context paragraphs:
Asnières (Van Gogh series): Asnières, now named Asnières-sur-Seine, is the subject and location of paintings that Vincent van Gogh made in 1887.  The works, which include parks, restaurants, riverside settings and factories, mark a breakthrough in van Gogh's artistic development.  In the Netherlands his work was shaped by great Dutch masters as well as Anton Mauve a Dutch realist painter who was a leading member of the Hague School and a significant early influence on his cousin-in-law van Gogh.  In Paris van Gogh was exposed to and influenced by Impressionism, Symbolism, Pointillism, and Japanese woodblock print genres.

Paintings of Children (Van Gogh series): Vincent van Gogh enjoyed making Paintings of Children.  He once said that it's the only thing that "excites me to the depths of my soul, and which makes me feel the infinite more than anything else."  Painting children, in particular represented rebirth and the infinite.  Over his career Van Gogh did not make many paintings of children, but those he completed were special to him.  During the ten years of Van Gogh's career as a painter, from 1881 to 1890, his work changed and grew richer, particularly in how he used color and techniques symbolically or evocatively.

Van Gogh's family in his art: Van Gogh's family in his art is a group of works that Vincent van Gogh made for or about Van Gogh family members.  In 1881 Vincent drew a portrait of his grandfather, also named Vincent van Gogh, and his sister Wil.  While living in Nuenen, Vincent memorialized his father in "Still Life with Bible" following his death in 1885.  There he also made many paintings and drawings in 1884 and 1885 of his parent's vicarage, its garden and the church.  At the height of his career in Arles he made "Portrait of the Artist's Mother", "Memory of the Garden at Etten" of his mother and sister and "Novel Reader", which is thought to be of his sister, Wil.

Trees and Undergrowth (Van Gogh series): Trees and Undergrowth is the subject of paintings that Vincent van Gogh made in Paris, Saint-Rémy and Auvers, from 1887 through 1890.  Van Gogh made several paintings of undergrowth, a genre called "sous-bois" brought into prominence by artists of the Barbizon School and Impressionists.  The works from this series successfully use shades of color and light in the forest or garden interior paintings.  Van Gogh selected one of his Saint-Rémy paintings, "Ivy" (F609) for the Brussels Les XX exhibition in 1890.

Auberge Ravoux: The Auberge Ravoux is a French historic landmark located in the heart of the village of Auvers-sur-Oise.  It is known as the House of Van Gogh ("Maison de Van Gogh") because the Dutch painter Vincent van Gogh spent the last 70 days of his life as a lodger at the auberge.  During his stay at Auvers, Van Gogh created more than 80 paintings and 64 sketches before shooting himself in the chest on 27 July 1890 and dying two days later on 29 July 1890.  The auberge has been restored and is now a museum and tourist attraction.  The room where Van Gogh lived and died has been restored and can be viewed by the public.

Copies by Vincent van Gogh: Copies by Vincent van Gogh form an important group of paintings executed by Vincent van Gogh between 1887 and early 1890.  While at Saint-Paul asylum in Saint-Rémy-de-Provence, France, where Van Gogh admitted himself, he strived to have subjects during the cold winter months.  Seeking to be reinvigorated artistically, Van Gogh did more than 30 copies of works by some of his favorite artists.  About twenty-one of the works were copies after, or inspired by, Jean-François Millet.  Rather than replicate, Van Gogh sought to translate the subjects and composition through his perspective, color, and technique.  Spiritual meaning and emotional comfort were expressed through symbolism and color.  His brother Theo van Gogh would call the pieces in the series some of his best work.

Early works of Vincent van Gogh: The early works of Vincent van Gogh is a group of paintings and drawings that Vincent van Gogh made when he was 27 and 28, in 1881 and 1882, his first two years of serious artistic exploration.  Over the course of the two-year period Van Gogh lived in several places.  He left Brussels, where he had studied for about a year in 1881, to return to his parent's home in Etten (North Brabant), where he made studies of some of the residents of the town.  In January 1882 Van Gogh went to The Hague where he studied with his cousin-in-law Anton Mauve and set up a studio, funded by Mauve.  During the ten years of Van Gogh's artistic career from 1881 to 1890 Vincent's brother Theo would be a continuing source of inspiration and financial support; his first financial support began in 1880 funding Vincent while he lived in Brussels.

Saint-Paul Asylum, Saint-Rémy (Van Gogh series): Saint-Paul Asylum, Saint-Rémy is a collection of paintings that Vincent van Gogh did when he was a self-admitted patient at the Saint-Paul asylum in Saint-Rémy-de-Provence, since renamed the "Clinique Van Gogh", from May 1889 until May 1890.  During much of his stay there he was confined to the grounds of the asylum, and he made paintings of the garden, the enclosed wheat field that he could see outside his room and a few portraits of individuals at the asylum.

Irises (painting): Irises is one of several paintings of irises by the Dutch artist Vincent van Gogh, and one of a series of paintings he executed at the Saint Paul-de-Mausole asylum in Saint-Rémy-de-Provence, France, in the last year before his death in 1890.

Green Wheat Field with Cypress: Green Wheat Field with Cypress (French: Champ de blé vert avec cyprès) is an oil on canvas painting by a Dutch Post-Impressionist Vincent van Gogh.  It was completed in 1889, while van Gogh was voluntarily incarcerated at the asylum of St. Paul near Saint-Rémy in Provence.  Several paintings of wheat fields with cypresses were made when van Gogh was able to leave the asylum grounds and explore the local landscape.  Besides a fondness for cypresses, van Gogh had a special affinty with wheat fields; he depicted them dozens of times over the years; to Vincent they symbolized the cycle of life and death, and he found in them both solace and inspiration.

Supporting paragraphs: Irises (painting) Saint-Paul Asylum, Saint-Rémy (Van Gogh series)
Answer: May 1889 until May 1890