Seeking feedback on an adventure Idea

Hi guys, I'm thinking of submitting the following to Kytos Hooks and thought I'd post it here to get some feedback first. It's the outline for an adventure designed for fairly low level characters to get them used to how planar travel works.
Anyway, here it is, feel free to be as critical as you like, I know my style needs some work.

Planting a rose in the Abyss – Party hired by the Rosebringers to spread roses across the planes, specifically- the abyss. Players are to plant 2 rose plants on the 289th layer “Don’t worry it’s more or less uninhabited”, wait for an hour, then report back on the results. They are given 2 small, potted rose plants and a small box containing a queen bee before being sent on their way.

To get there the players need to find a way there. At least 2 stops – layer 1 and layer 634. This info should be relatively easy to discover, maybe a diplomacy check and a bit of messing around at the hall of information or tracking down Azriael (I use him, ignore this if you don't) and picking his brain for a while. The portals to the layers are relatively close together and the players should be able to find out a fair bit about them if they take the time and pass a few checks, the more they research, the easier the adventure becomes.

Layer 1 – The plane of infinite portals. Getting here should be pretty easy, in fact any Tanar'ri you ask will probably be happy to give you directions however another source is more likely to send you to a portal that's a bit closer to the next one.
Once you get here - RUN! Get to the next portal as quickly as you can and try to avoid the notice of the multitude of fiends, it should only be a couple of hundred metres away and looks like a mud puddle. The key is to spit into the puddle.

Layer 634 – Slime, acid, etc. Possibly battle an ooze. This layer is unpleasant and unless the players are prepared they suffer 1 hp of acid damage every d20 minutes. Portal takes the form of a tangle of razorvine on a piece of solid ground. The key is a spell/item using positive energy Once again the distance to the portal depends on how much preparation was done.

Layer 289 – A vast field of soft earth, dimly illuminated by a glow that seems to come from the air itself. Nothing much seems to be about other than a few stone circles on the ground (one of which the characters come out of and another which opens when the characters bring a rose near it). This layer has a minor positive trait in this area and shifting pockets of major Positive trait (hence the lack of creatures, most of them have ‘popped’) as well as minor Evil and Chaotic traits- things grow all right but they do so in a random and somewhat malevolent way. By freak chance no vegetation has ever taken root on this layer. Once the rose is planted the earth that it has been carried with contains all the tiny living organisms that are needed to support it’s growth. Grow it does and while the PC’s watch the rose grows and propagates, the bees produced by the queen spreading the pollen. Roses quickly spread as far as the eye can see and by the end of the hour the field is covered by them.
Unfortunately over the course of the hour the PC’s need to defend themselves from a couple of bee swarms and a giant earthworm which are now also breeding and growing incessantly. The PC’s might also have to face any traces of slime & ooze left over from the last layer as these grow rapidly in the positively charged layer.
Once the hour’s up the PC’s can leave, mission fulfilled. Unfortunately the original portal will not open with the same key so unless the party has plane-shifting magics it’s on to the next adventure (I suggest “when travelling near evil”).