I know that both Dravanian Mistletoe & Coerthan Tea were made available from a vendor in Ishgard shortly after 3.0 launch when it was realised that these are essential items for popular crafts. They may only be used in 1 & 3 crafts respectively but 3 of those crafts are basic materials used in so many more.

Both are gathered from timed nodes so are limited in nature, however, unlike other timed node materials they aren't available via retainer ventures. This makes gathering significant amounts very difficult, especially if you are trying to make HQ items at lower levels & require HQ mats.

Tea seeds are available but Mistletoe aren't. I've also found that when I planted 4 seeds using G3 La Noscean Soil I only got 9 NQ & 3 HQ. A low HQ yield.

TL;DR - These need to be available via ventures & Mistletoe seed needs introduction. Thanks.