To really be a lot of help, I'd need to know more about the story, but here are suggestions you can try to work with and don't be afraid to cherry pick the ones that seem to work for you:Start with mapping out what you know.
Any information, however trivial it might be (ie, everything from characters' favorite colors to childhood tragedies--anything you know.) Add "Spark's notes" of whatever action scenes you have in mind. Put it all in a list. It doesn't have to be neat, but just so you have the info in one place and can work with it. (I usually recommend writing it out in a notebook, or note cards, or even post-it notes; even if you're used to using a computer) You can color code this (yellow for a particular character, blue for an event, etc.) but chances are you'll change your mind about things, so only color code if it's helpful
Doing this will allow you to look at the whole thing and see it in a different light. You can find connections in the story and bridge gaps between one scene and another.
Pick the known elements--the action scenes for example--and start asking questions about them.
Usually when you're plotting, the three most productive questions to ask are "what" "how" and (even more) "why". Why is the best possible question to ask when you're plotting:
Are two characters having a fight? Why are they angry at one another--what old wounds have awoken in them to turn an argument into a brawl?
Why are the stowaways trying to get back to their original home now--so long after they left it? Even if this is their first chance to go, there still has to be some massive reasoning behind their actions. It's been a long time, they've had to make a life for themselves, going back is a huge deal. So why now? Why do they miss home the most? What was their home like when they left it and how do they think it will be when they go back?
Why did the rocket hit the meteor cloud and become damaged in the process? The people plotting the course must have had some idea it was there and taken precautions.
And for goodness' sake, why is the one stowaway trying to kill another?
You know your story better than I and may already have answers to these particular questions, but those are some examples of the kinds of questions you can ask. The more in-depth and detailed you can make both the questions and the answers, the better.
And don't kid yourself about the action.
Yes, the readers need a breather and yes detail and conversation and background are important to a story. But we don't want a dull story do we? Not with meteors, aliens, stowaways, and people trying to kill each other.
Do what you have to in making the story work and spread the action out, but try not to force yourself into anything
until you believe it's right for the story. Whether this means removing action or adding to it, you'll be able to figure it out as you learn more about your characters and story.Ask yourself what you're trying to prove in this story.
What theme you want to come across. Is it friendship and loyalty? Is it the foolishness of revenge? Themes are hard for me, but most of the time my stories come down to friendship, loyalty, hope, and trust. These are things I care deeply about and have a desire for, so they come through in my writing whether I want them to or not. See what comes out in your own writing. Can't think of a theme? Don't sweat it. You may not figure it out until the last chapter or later.
On the other hand, give your characters a theme.
A passion. A reason for being them. What do they want most? Pull some character questionnaires off the Internet (they're easy enough to find, or I can pull out some I have and send them to you.) Take time to answer the questions for each character, using a different set of questions each time if you want/need. These are your characters and you care about them. Figure out why you care about them and--perhaps more importantly--why your readers should care about them. Learn everything about them. For some of your characters, the perfect answer can pop into your head as soon as you read the question. For others, it will be like dragging yourself along by your fingernails and teeth. Hang in there. Answer the questions and don't give one character the short end of the stick.
Trust me when I say that the more deeply developed your characters are, the more story you will have to deal with. You might even end up with too much for the space you have. If your characters are developed, you need never ask "where's my story?"
You can also try writing from different POVs. Write about things that maybe don't happen in the story, but are connected. Background. Write about how and why the aliens got stranded. Or why earth decided to send kidnapped people into outer space. Etc. This will make your story world seem bigger and brighter and give you more to work with.
Two more suggestion before I stop this long-winded post: (You can always ask for more ideas if you want)Find the Point of No Return
In every story there is a point of no return. A doorway through which the characters step that forever changes their world so that it will not be the same again. It forces them to act, to move on ahead, and to not look back. Without this point, or door, the character is free to roam about the story unhindered. For your story it could be the moment the characters are kidnapped, or it might be something that happened earlier which set them down on that path. For the aliens, maybe something happens that means they can stay on the earth no longer even if they wanted to. Or maybe their point of no return happens on the spacecraft, some event in their interaction with the other people that sets something into motion. (Really though, the spacecraft itself is a sort of point of no return.)Build a bridge.
This is possibly one of the best and simplest story plotting illustrations I know. Imagine that your story is a bridge. A bridge like the Golden Gate is the best to think of. Imagine two high points at either end, with the cables bowing in-between.The first high arc is your point of no return.
It's the event that sets everything else in motion. The something that forces the characters to be or do or act. It can happen in the first sentence, or the first five pages. Usually, it should happen somewhere in the first chapter or possibly the second, unless the story is a calm sort--which I get the impression that "Seeds" is not. The middle portion--the bowing cable--is where things can slow down a bit.
There's still action, still conflict, but you can breathe. You can dig into your story and get to its soil and roots. Show off your characters. Snap pictures of your world. You can allow yourself to come down from the excitement or drama of that opening point. But then you build up to the second.
Probably, the characters haven't really figured out who or what they are in the story just yet. They're beginning to in this section. Things are coming together. They're working toward a goal. Your characters should be figuring things out, getting a feel. They have a plan. They know what they're doing. If there's a villain to face then by this point they generally know who/what it is and are preparing to do battle.Your final point in the bridge is your end climax.
This happens at the end of the book, somewhere in the last five chapters or so. It's the battle against the villain. It's the discovery. The rescue. The hurricane. The final battle. Everything you've said in the story so far comes to a head right here.
And then you have your space for tying up the story nice and pretty.
I learned both of these last two from James Scot Bell's book Conflict and Suspense
(I highly recommend this, and others in his how-to series of writing books).
I hope this helps. Again, since I don't know your story, I'm giving pretty generic tips. If you want me to clarify or explain anything, just ask. If your looking for more/other ideas, ask that too.