Bonsai have a very small amount of soil to rely on for water and nutrients,so it is vital to attend to these needs regularly. Apart from regular watering, Bonsai need periodical fertilising and protection from insects and diseases. Sunshine is vital also, yet they must be shaded from the kind of hot afternoon sun we get in India during the summer months.

Bonsai need thorough watering— till the water runs out of the drainage holes.
In addition, the foliage should be sprayed every few days to get rid of dust and pollutants which clog the leaf pores.

It must also be ensured that the soil and the pots drain well. Soggy soil kills trees faster than dryness.

All plants require Nitrogen(N), Phosphorous(P), and Potassium(K) for healthy growth.
In spring when the plants are putting out leaves a nitrogen rich fertiliser is needed.
Later in the year, when growth is shutting down for the winter, a PK rich fertiliser is recommended to harden off the year's growth and see the plant safely through the winter months.

Every bonsai grower probably has a secret fertilising formula. Here is ours: Neem khali is our N-rich fertiliser.A kilo packet is poured into a 25 litre bucket of water and allowed to rot for four to five days. Then the trees are fed with the liquid diluted to one part in five every fortnight from mid-February to early May. No fertiliser is used through the summer and the monsoons. Then we switch to PK rich fertiliser, using bone meal and sterimeal (blood meal or fish meal) alternatively every fortnight from mid-September to early November, stopping altogether for the winter.