Pharmacist Lars Henrik von Mell helped Rothstein into the clear by buying Qvidja from him in 1777. von Mell made remarkable effort to renovate the deteriorated estate, particularly the castle, which received its current shape during his time as the owner. The manor’s garden was also expanded in the course of the 1770s and 1780s. It is known that von Mell owned a tobacco plantation and a medicinal garden, but they may have been located outside of Qvidja.

After von Mell died, the estate was passed on to his widow, Hedvig Dorotea, and when she died in 1800, the estate was inherited by von Mell’s daughter’s husband, captain Anders Johan Prytz. Captain Prytz and his family lived at Qvidja. When the estate was owned by the Prytz family, prop painter Hellstén from Turku was commissioned to create wall paintings in the large hall of the main building, which could indicate the elevation of the status of the building to that of the main building.

After Captain Prytz died in 1824, his widow – pharmacist von Mell’s daughter, Hedvig Maria – remained as the owners of the estate. She managed the estate for another 40 years. Hedvig Maria Prytz constantly organised lively social events.  Several authors and artists visited the estate. During her time, the habit of weighing each visitor was started, and the greystone castle’s large grain scales were used for this purpose. Each visitor’s weight was recorded in Qvidja’s book of scales, where they still exist today.

The book reveals that Johan Ludvig Runeberg weighed eight lispounds and five pounds, or just over 70 kilograms, when he visited the manor in 1827. The significance of the estate is also denoted by the regular steamboat connection, which started operating from Turku to Qvidja in 1859. By 1922, the steamboat pier had been moved to Kassori, two kilometres away.

When Hedvig Maria Prytz died in 1863, the manor ended up in the possession of her granddaughter’s sons, Carl Johan Wolmar and Lars Oscar Wilhelm af Heurlin. The brothers, Wolmar and Wilhelm af Heurlin, commenced renovations, which were probably the largest in the manor’s history. The new main building was completed in 1866. Wilhelm gave up running the estate already in the 1870s, but Wolmar continued by adding a steward’s house in the courtyard in the 1870s, a new gardener’s house in the 1880s and a dairy in the 1890s. Most of the buildings in the current courtyard date from the era of Wolmar af Heurlin.

Wolmar af Heurlin concluded his military career in 1868 and focused on developing agriculture at Qvidja. He acquired new plant varieties, combined small strips of fields and underdrained new fields. Cattle rearing was made more efficient by constructing a modern brick-built cowhouse, which still stands in a visible location in the housekeeping yard. Mechanisation of the estate was commenced by acquiring a modern harrow and a mower, as well as a seeder in the 1890s.

In 1872, a steam-powered sawmill and a steam-powered mill were constructed on the estate, as well we as a tar burner by 1906. For his development work, Wolmar af Heurlin was appointed as the Counsellor of Agriculture. The same honorary title was also granted to his son and grandson, which indicates the quality and value of the work carried out at Qvidja.

Wolmar af Heurlin’s son, Alexander Vilhelm af Heurlin, became the owner of the estate in 1908. The estate continued to grow and new residential buildings were constructed for its employees. According to the inventories, a bakehouse, a carriage shed, storage for agricultural machinery and a workshop inside the former brewery were added by 1924. Additionally, a cemetery for the af Heurlin family was established on the island’s northern shore in 1919.

By the 1920s, there were already 600 hectares of cultivated fields. The steam-powered sawmill had become unprofitable so operations were ceased in 1918, but a brick factory was founded in 1928 and a bridge was built to connect the island to the mainland. The workshop in the courtyard was converted into a chapel in the beginning of the 1930s.

Wilhelm af Heurlin’s widow, Margareta af Heurlin (née Aminoff) managed the estate in 1934-1949. During her time, renovation work was concentrated on the main building. In 1949, agrologist Håkan af Heurlin and his wife Elly Aminoff, who had inherited the estate, also made extensive changes in the main building.

When the land was redistributed after the wars in 1952, approximately 40% of the estate, mainly forested land, was sectioned off to residential farms. At the end of the 1950s, there was a survey comprising the manor estate and the stone castle and the older cellars of the main building were measured. The manor was named as a historical and cultural protected site in 1967 and as a nationally significant historical and cultural environment in 1979.

Starting from 1976, the estate was owned by Håkan and Elly af Heurlin’s son Anders af Heurlin, who engaged in agriculture and expanded beef cattle production. At the end of the 1990s, an alternative to keeping beef cattle was sought in the hotel and leisure centre, which was being planned for the vicinity. The construction inventories and the partial master plan created for the centre resulted in a significant portion of the farm’s buildings being marked as protected. However, the project never materialised and the cultivated land has since been mostly rented out to outsiders.