How do you ensure seedlings receive the water and nurturance required to grow into trees, after planting?

All our projects take a holistic approach to tree planting, to address this. Specifically, this means:

1. The saplings planted are always propagated from native species which are suited to thrive in the region, once they take hold, if left alone.
2. In hardier regions, significant effort is spent on selecting the progeny that has the highest chance of survival and reproduction. This is a nice blog post by our planting tech partners on how the best progeny is selected in our Pacific Northwest project. 
3. Systemic changes are made to improve survivability. Here is a post capturing how trenches for example help the ground water recover over time to achieve the right level of salinity in our Mangrove project in Kenya. 
4. Tech is deployed to monitor conditions of the environment. Here's a comprehensive example of how pH sensors are used to ensure the right pH levels for our young Kelp forests in Canada. 
5. And most importantly, our projects hire people from the local community, which not only creates employment in the community, but also ensures that a small presence can be maintained for continued monitoring long past the initial planting sessions.