There are so many ways to advertise in today's technical world; whether through a website, online ad spaces, direct mail or coupons, word of mouth, radio or TV ads, social media presences, etc. Find a niche where your business fits, and maintain a vision for how you'd like to interact with your customers.
Online search engine ads can be fine-tuned to direct potential customers towards your website and/or greenhouse. Work with someone who has experience in online search engine optimization so that they can find the best way to get your message out there.
