Staff from the county council will also observe a minute's silence at 12 noon to mark the day.
A national initiative, the Social Care Day of Remembrance and Reflection gives people the opportunity to remember adult social care workers who have lost their lives to Covid over the last two years.
The campaign, supported by 21 care organisations, also encourages people to reflect on the important role social care has played in supporting adults throughout the pandemic.
County Councillor Barrie Yates, chairman of Lancashire County Council, will lead the tree planting ceremony.
He said: "Covid-19 has had a huge impact on our community and our adult social care workforce, who have been on the frontline working tirelessly to support people, often in difficult circumstances throughout the pandemic.
"Unfortunately, many workers lost their lives to Covid, including some who worked for the county council, and the day is an opportunity to remember what they did for the people of Lancashire.”
County Councillor Graham Gooch, cabinet member for adult social care, said: "It's very important we all remember the tremendous efforts of those who have supported adults who need social care throughout the pandemic.
"They have coped with unprecedented challenges but supported people to continue to live as independently as they can despite the difficulties that Covid led to.
"We must never forget those who lost their lives and the memorial tree will be an important reminder for us all."
Nationally, people are being encouraged to mark the Social Care Remembrance and Reflection Day by signing a memorial wall on the Care Workers' Charity website, to take part in an a candlelit vigil at 8pm and to share any messages on social media using the #RememberSocialCare hashtag.
The British Association of Social Workers will also be running events and Skills for Care are hosting an event attended by MP Gillian Keegan, Minister for Health and social Care. More details are available on the Skills for Care website.