Consumables...

There's potted plants (Doom Shrooms, Lightning Reeds, etc.), Weeds (Hypno Shrooms, vase plants, etc.), Bots, and Zombies. Bots and Potted plants can only be used in the Ops games, while the other two in Gardens & Graveyards and Herbal Assault.

Welcome to the garden. (some info will be very general)

For plants, there are golden shiny clay pots throughout the map. Specifically for the Flag, there should be 4 surrounding the Flag. You interact with the shiny pot and it gives you the option to plant a weed into it. There's a small screen on the upper right hand corner when you do it. Select the plant you want and confirm.

Plants have hps, unique abilities, and can be killed or healed. They cannot be revived.

Zombies have something similar but it looks like piles of dirty with trash scattered about in it.

Plants & Zombies in other game modes have consumables that are mobile, just need to find a pile of dirt that's highlighted and you can interact with. They're hard to miss since they tend to be shiny and golden.

Only certain plants and zombies can be summoned/raised/planted in pots or dirt.

Hope that helps.

I'd recommend using those consumibles any time you get the change, and not store them by the hundreds as many people do. Keep in mind that the summoned attacking plants/zombies can have a major impact in Turf mode and you'd be surprised how often these minions prove to be more effective than the rest of the team.

Some consumables spawn a stationary "tower" (used to defend the flag in garden ops) other are used to spawn a mobile NPC "soldier" (used to attack in turf wars).

For example your weeds and dandelions are mobile "soldier" spawns and can not be used in Garden Ops or be planted in the pots around the flag of power.