Timber companies set up dummy companies in order to get round the 1915 legislation which restricted their land procurement. In Jämsänkoski, land was purchased under the name of Maanviljelysosakeyhtiö Päijänne. The farms were situated in the Jämsä and Kuhmoinen areas, and a few forest estates in Vilppula, Multia, Keuruu and Petäjävesi. By the time it was merged with United Paper Mills Ltd in 1920, the Jämsänkoski factory had estates of 6,600 hectares, of which 4,300 was forest.

United began systematic husbandry of its forests at the end of the 1920s. Planting of new forests was a target for special attention. Broad-leaf forests of low value at the time were turned into spruce forests, as spruce was the most important raw material of the company's factories. Worried about maintaining sufficient supplies of spruce, the company organised a forestry contest for forest owners in the parishes near its factories in 1935. In Jämsänkoski, even schoolchildren took part in forest planting bees in the last school days of spring. In 1938 United owned a total of 36,800 hectares of forest, of which the share of Jämsänkoski factory was 6,500.

From 1918, the Jämsänkoski factory had employed a forester to co-ordinate the company's timber supplies. The supply area was bordered by Lake Päijänne and rivers running into it. Expansions of production at the factories in the 1930s also increased the raw wood requirements. Due to low levels of water power, firewood consumption at Jämsänkoski was greater than at the other United factories. Only a few percent of the necessary quantities of timber were obtained from the company's own forests.

The supply area of the Jämsänkoski mill covered the districts of Jämsänkoski, Kuhmoinen, Petäjävesi, Joutsa and Saarijärvi. As there were no railways, the supplies had to be concentrated close to floating routes. Timber was purchased both on the stump and at delivered price, which was the main method of raw wood buying. In a delivered sale, the seller was responsible for logging and transport to a main transport route. Earlier, the trunks had been half-debarked in the forest, but the new drum debarking plant completed in the mid-1930s increased the amount of debarking done in-house.

After the company was split up, United Paper Mills Jyväskylä forestry office was established, and the timber supply area was extended to the northern parts of Central Finland and Savo. After the war, the price of timber had risen sharply. Spruce still accounted for 2/3 of all the raw wood required by the company. Jämsänkoski pulp mill had partially used broad-leaf timber as raw material as early as the 1950s. Kaipola also used small quantities of pine and aspen imported from the Soviet Union, although it weakened the quality of the paper.

Motorised transport and the chainsaw became common at logging sites from the 1950s. In the 1960s, tractors and trucks replaced horses in logging work. Road transport gradually replaced floating, but at the turn of the 1950s, a 2 - 3 week floating peak in the spring still provided work for 400 - 450 local labourers. The last log float on the Jämsä route, from Koveroinen to Jämsänkoski, was done in 1965. About 80 percent of raw wood for Kaipola arrived by floating in the 1960s.