A tablespoon is a non-scientific but very widely used unit of volume, which works very well in cooking, herbal medicine, etc. It is represented by a capacity of one tablespoon which varies from roughly 15 mL in the US to 20 mL in Australia.
1 If tea is properly stored, it can potentially last up to a year for green and black teas. White tea lasts about six months before it isn't as good in quality as when fresher. Stale tea (or bad tea) will taste flat, as if you're drinking paper.  Glass or ceramic containers are fine provided that they're opaque.
1 For container plants, the tea can be diluted to one part of tea to two parts of water and given once every few weeks depending on plant condition. 2  For trees and shrubs, spray undiluted two weeks before bud break and then every 10-14 days at 1:5 part dilution. 3  For seedlings, mist or soak seeds prior to planting.