Best Botanical Gardens?

I wondered if there would be any as they are most often created by European colonists. A Google search gave me http://www.forest.go.th/Botany/Gardens/Botanics&arboreta.htm</a> which looks like a useful link for you - more on a search botanical gardens thailand. Nong Nooch Gardens near Pattaya and The Rose Gardens near Bangkok may be of interest.

The Princess mothers gardens up north at Chang Rai are very impressive! They are called 'Mae Fa Luang Gardens' at Doi Tung. Very formal and spectacular. We saw them as part of a day trip around the Golden Triangle from Chang Rai. Cheers WilliP

Nong Nooch,is very good.Its just outside Pattaya.

I was very impressed with the Queen Sirikit Botanic Garden at Mae Rim near Chiang Mia. Time only allowed me to spend three hours there, but could have easily made it a day visit. Entrance fee of 30 Baht.
Spectacular glasshouses and there are also 6 walks to differant areas all taking between 30 and 45 minutes.