You need to start considering your company's reputation as an employer of technologists. If there is no reputation, you need to start building it. Perhaps sponsoring a meetup for a few hundred dollars is a good investment, as it shows your company supports the community. Perhaps one of your engineers could speak at a meetup, to show off some of your talent or give a sniff of your interesting products and projects.

Once you've built a bit of a hiring brand, you'll start to see incoming traffic coming in organically instead of having to go and do outreach all the time.