Rubber estates run by government research institutes which used rain guards were able to make good profits, he said.
"So we want to make rain guards more available, especially to encourage rubber small holders to use them," he told a news conference.
"Then we can increase rubber production, raise farmer incomes while ensuring enough supplies are available for industry."
About 72,000 small farmers cultivate rubber on 33,000 hectares in the island while listed plantations companies cultivate another 50,000 hectares.
Samarasinghe said even among the plantations firms use of rain guards was inadequate.
Sri Lanka's total rubber production is now around 130,000 tonnes and the country is estimated to need 150,000 tonnes by 2015, Samarasinghe said.
Local consumption of rubber by industry has risen sharply in recent years.
In 1980 only 10 percent of rubber was used locally.
Today 80 percent of production is used by local industries which have had to cope with record prices in recent month owing to global shortages and rising demand.