Blue Flower Edit
Blue flowers can be found all over Tundra Biomes all over the leaves. They are used in many crafting recipes and to make blue pigment in the processor. They are also found commonly in loot crates and are given in loot drops.
Blue Flowers can be found on pinetree-like Elderwood-trees growing on and among the leaves. These flowers are blocks that can be placed and even used as building-material. Blue Flowers usually are not existent from the beginning on snowy Elderwood-trees with Snowy Elderwood Leaves, but Blue Flowers can grow on them in time, albeit very slowly.
Blue Flowers can also be found in Wood Treasure Chests spawning in the night in unlit spots on natural blocks on the surface, and can be looted or pet-harvested from Chizzards, Night Chizzards and Blizzard Chizzards occasionally.
On top of placed flower-blocks Leafis might rarely spawn, at night / in darkness also Night Leafies, even if the flowers were placed as a decoration inside a house made of crafted blocks. If placed into Flower Pots or Wood Planters, the flowers will not make any creatures spawn though. They glow very, very faintly in the dark.
Elderwood-trees can be grown from Elderwood-Saplings (an additional harvest when gathering leaves), but only in fitting environments. Grassland is not always a good place to grow them, but Forests usually are fit. Trees can be grown on Grass-blocks with some Water not too far away (a few blocks, probably the water has to be in the same chunk 16x16x16 blocks large). The water can be a natural body of water or water that you placed yourself. Saplings can be fertilized by Pigsy Droppings, but only if the Saplings aren't fallow, because in this case no tree will grow from them at the chosen spot anyway.
More Blue Flowers will - slowly - grow on Elderwood-leaves with time, so you can lay out flat artificial biomes made from Elderwood Leaves and wait for a few (real time) days until you can collect one or two Blue Flowers there every couple of days or so. The same goes for Red Flowers, Yellow Flower and Wildwood Flowers; not for Autumnwood Flowers nor Weepwood Flowers though, as they currently (R25 in November 2015) do not regrow.
A faster method to get more Blue Flowers is to place blocks of Blue Flowers on the ground and pick them up again - once in a while you will obtain 2 flowers at once when doing that.
Blue Flowers are necessary to make Flares and Blue Pigment in a Processor. Blue Pigment is used for crafting Blue Beacons, Blue Lamps (Wood Burning Lamps emitting blue light), Purple Block of Goo, Blue Fireworks, Blue Stained Glass, Blue Beds, Blue Concrete, Blue Mosaic Tile Wall, Blue Adobe Floor, Blue Adobe Roof, Blue Adobe Wall, Blue Carpet and Blue Wood Wall.
Blue Flowers can also be used as an ingredient in Basic Health Potions, Stone Mining Cells, Taming Collars, Golden Potions, Stamina Regeneration Potions in recipes where you can choose from different possible flowers.