NiteHawke13

Only two suggestions. First is Xenograft which would let you add 'Fungus' to the creature type of your saprolings so they gain the spore counters from Sporesower Thallid. Second is (if you have it or can trade for it) Followed Footsteps to enchant Sporesower Thallid.

Having just joined, I found this deck and thought of a few possible improvements.

First off, you are using hivestone and gemhide sliver to make all of your saprolings slivers for mana. That is great as far as it goes, but there are other abilities from slivers that can help as well.

For instance, there is Predatory Sliver which gives sliver creatures you control +1/+1 for a CMC of 2 vs Thelonite Hermit's CMC of 4 (more if you morph it for the saprolings). Alternatively you might consider Might Slivers instead for +2/+2 for each sliver, though it has a CMC of 5.

Then there is Fungus Sliver which gives all slivers "Whenever this creature is dealt damage, put a +1/+1 counter on it." I would argue that the +1/+1 counters are better than the +1/+1 until end of turn that Thallid Germinator gives, and it is still a fungus so Sporesower will give it spore counters that Sporoloth will let you wake into saprolings, even if it's just a tiny bit slower.

Aditionally, since Glorious Anthem and Leyline of the Meek give +1/+1 which is replaced by the Predatory Sliver and Might Sliver, I would remove both, and add a pair of Xenograft. Xenograft does basically the same thing as Hivestone except that it allows you to name the creature type. Therefore you could substitute it for the hivestones in the event that you can't draw one by naming slivers, or (more importantly) name Fungus, so that each saproling you control becomes eligible for sporesower's spore counters, and Sporoloth's ability.

Finally, once you have xenograft making all of your saprolings fungi, I would reduce Utopia Mycon from four to three and Fists of Ironwood from three to two, and add two copies of Thelon of Havenwood which gives them +1/+1 for each spore counter that Sporesower gives them.

End result:
Remove
2x Thallid Germinator
2x Thelonite Hermit
1x Utopia Mycon
1x Fists of Ironwood
2x Glorious Anthem
2x Leyline of the Meek

Add
2x Fungus Sliver
2x Predatory Sliver
2x Might Sliver
2x Xenograft
2x Thelon of Havenwood