Plants can be grown both in open soil and in enclosed pots. But in both the cases, you have to ensure proper ventilation, enough nutrients and appropriate porosity of the soil. To prevent yellowing leaves, the plant should be able to attain the nutrients and water needed for its growth from soil. There is simple method to check the porosity of the soil. Try inserting your finger into the soil. If your finger cannot go 2 inches in, then the soil is not porous enough.
Pour a diluted solution of (20 gm in 1 litre of water) pseudomonas at the base of the plant. Greencare used in a ratio of 30:10:10 is also very good to boost the growth of the plant. Flowering plants will start flowering properly. Orchids and similar plants will benefit from a mixture of Greencare in the ratio of 13:27:27. Vegetables and fruits too benefit from this mixture.