People who are serious in "tree growing" and not just "tree planting" do NOT plant trees at the end of the rainy season, ie, end-October or November. They plant in June (or late May), at the start of the rainy season. Those seedlings are still frail, unless they are at least 3 feet tall already, meaning their roots and stems are already hardened from strong sunlight.
My observation as a practitioner of agro-forest farming for more than a decade now, is that if you plant at the end of the rainy season, and you don't water them for the next 5 months at least, plus the necessary cleaning of undesirable weeds and vines that compete for sunlight and soil minerals, survival rate of those seedlings after 1 year is only around 10%, you're lucky if you get 20-25% survival. The rest are dead, sayang ang pagod, sayang ang seedlings. And if grass fires occur (they usually occur anywhere from January to May), you'll have zero survival. The tree planting activity then would be good only for picture-taking and project reporting.
Whereas if you plant at the start of the rainy season, you save on labor and watering for at least 5 months straight. By the time the rainy season has ended, the seedlings have already developed strong roots that will allow them to penetrate deeper sub-soil for water and minerals. That is why survival rate is much higher.
If the seedlings are still small, ie shorter than 3 feet tall, better keep the seedlings in one place, remove the small plastic bags that hold their roots, put the seedlings in bigger plastic bags, add more soil, water them regularly, and plant them June the next year, at the start of the rainy season. By then, the seedlings should be at least 4 feet tall, would have vigorous roots and will have much bigger probability of survival. Those who will plant the seedlings would also be glad to see that the small tree they have planted are already tall, taller than grasses and weeds.
Groups that are intent on planting at the end of the rainy season should allot more money to hire laborers who will regularly water those plants, remove the competing grasses and vines, apply fertilizers (organic or inorganic), and replant those that died. The cost here should be higher. Nonetheless, people should be aware that it should be a "tree growing", not just a "tree planting", activity.
Finally, for people who want to see real big trees someday, better that they buy lands in the provinces, just a few hectares, and do what they want or plant what they want. If they want "bio-diversity", they can plant several dozens of different species of trees, from fast-growing commercial species to slow-growing, dipterocarp and vanishing species. The area can be made later into an income-generating eco-tourism resort, or for bird (or some wild life) research sanctuary, the options are unlimited.
Planting trees on lands you do not own, especially if it is "public forest land", meaning "owned and managed" by the DENR, is very often a waste of time. It is because if you have open access to plant those trees in those lands, other people also have the same access to cut those trees on those lands someday. The DENR is the biggest manager of lands in this country (in behalf of the state that owns all lands). It is also the lousiest and laziest manager/s. If you want to check or refute this, try to visit any nearby "public forest land" and estimate the percentage of that area that still has thick forest cover.