I recommend a book, Called from seeds to leaves, by Doug & Robin stewart.
I like this book because it states how to germinate many seeds from Australia how to harvest them and process them and grow them on a micro to industrial scale.
However this is used for Australian seeds the list of Process is extremely in-depth and easy to understand both visually and textually!
Additionally many threads on this site show how to process seeds in many different ways!
Now to the business aspect!
As my father says, If your going to do any business start with a cash flow projection!
this means costs of doing business and predicted earnings!
90 percent of the time you will over estimate your ability on this!
you will want to identify your target market!
you will want to select a first draft of what type of seeds!
you will look at where your competition is and where your customers are!
most customers least competition!
you will want to market yourself this means branding and presentation, you can look at comperable designs and systems
and use these to exopodite your development!
you will want to network and find friends and mentors!
you will want to Look at your point of sale systems!
you will want to look at sampling the market in small quantities in a test venture this is likely to be in market stalls!
This will likely be frustrating for the first venture!
After this you will want to evaluate moving forward!
If you consider moving forward make sure your customers have consistent and reliable products with clear communication and good customer relations!
and with this product set yourself apart from everyone else with a point of different! Increase your value by increase the opportunity value of a customer buying your product and not someone else's!
Initially you will want to stay in a small but focused variety of products!
If you want to invest in custom markets and signs do so, but also realise the over head of this and the logistics of this, you may want to consider setting a period of time into studying business and commerce and looking at how to save on taxes! and learning about the copyright law!
Ideally you want to move away from individual sales and into larger sales such as 200 to a nursey etc at a time, or supplying to a construction company or landscaper, this will mean consistent and reliable income.
Or you could supply an environmental group such as is done by two sister in south America, who finance reforestation by selling seedlings!
But this also comes with added bureaucratic and political risks, so it is best avoided because of the volitivity of such a process!
I hope some of this information assists you!