Tongdewei is not in Yuexiu District, but in Baiyun District. There are no subway stations near south china botanical garden and Tongdewei.
If you want to take the subway, take bus No.39 at Botanical Garden Station, get off at Tianhe Bus Terminal, and then transfer to Sanyuanli Station on Line 2. Transfer to Bus No.975 to Tianxin Village, Tongdewei.
Tongdewei Station (Tianxin Village)-Lide Road Junction-Tongde Township-Shangbu Village-Hengjiao-Tangxi Village (Xicha Road)-Tongdewei-Kangde Road-Sanyuanli Avenue Middle-Tangxia (New City)-Shachong (Sanyuanli)-North Station-Subway Sanyuanli Station-North Station-Shachong (Sanyuanli)