The Echinopsae go down easily even when they pop up in pairs so it's likely the Archspore that's giving you a hard time since it can creep up in several locations in the swamp.

Gob 2 pots, 1 swallow, 1 tawny, and then hit the thing with Igni Sign + silver strong style. The Poison Resistance upgrade in the stamina tree helps a lot as does the Incineration upgrade in the Igni tree.

That would be the ones - so what do I do when those pop up in pairs? Run and hope I have enough health on my way back?

The tactics for the Echinopsae and Archspore are the same, it's just that the Archspore is one of those though "boss" like monsters that drops a trophy.

The Echinopsae go down easy, you already tackled them in the Outskirts during the course of the main quest and if you did a certain side quest you already tackled a cave full of them.

The Archspore 'boss' is a single plant, it won't pop up in pairs because there's just the one. Try taking him out in the road that goes right from the clay pits, follow that road and he'll creep up in the first or second turn of the road, no other plants will pop out there so you can focus exclusively on him.

You can always just run past all the plants in the swamp untill you leveled up some more and then come back to it.

I'm mostly familiar with FCR1.6 so some may not apply to vanilla game:

Later the silver sword is a useful option, but earlier in the game, Echinopse and Archespores are best dealt with using the torch, and Igni.

It ignores armour, can cause incineration (even if your Igni cannot *yet*)... which is useful. Set one on fire, switch to your best "group" sword style and sword (damage doesn't matter, you are looking for deflection, dodge and parry) and back away using "double taps" to increase dodge by 25%. Wait just outside the range of the thorn projectiles, but close enough they don't 'despawn/respawn' until the flames go out or you have recovered lost health, rinse and repeat.

Don't try to stand and fight more than one. Or the 'boss', unless you have improved your skills a bit more.

If you can *hit* with group, the fear option prevents attacks and they cannot run away... however the -6 damage reduction may make this unusable when you first meet them.