1. Where to Start
If you're planting 20 pine trees on a plot, it's important to understand: a forest is more than just a group of trees. It's an ecosystem: trees, undergrowth, animals, and microorganisms.

2. Pine Growth

Young pine trees grow approximately 30-50 cm per year in the first few years, if conditions are favorable.
After 10-15 years, they can reach 3-5 meters, but this isn't yet a forest - more like a sparse pine forest.
It takes 50-80 years or more for pine trees to form a dense, mature forest with tall trees and natural undergrowth.

3. Factors Affecting Growth

Soil and Climate. Fertile soil and proper watering accelerate growth. Maintenance. Weed removal, pest control, and thinning all help trees grow strong.
Planting density. Twenty trees in a small area won't create a forest quickly. A true forest requires hundreds of trees to create undergrowth and a natural balance.

4. The term "forest"
By definition, a forest is an area where trees occupy more than 10% of the area, provide shade and undergrowth, and the ecosystem functions naturally. Twenty trees are more of a patch of trees than a forest, especially in the first decades.

Key point:

Planting trees is an investment in the future that requires patience.
With 20 pines, you'll see growth in 10-15 years, but a true forest is a project that lasts for decades and even generations.
If the goal is to create a true forest, it's important to plan broadly: more trees, maintenance, species diversity, and a long-term strategy.