Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- Muslims are required to keep the environment around them pure and clean.
2- True Muslims are those who appreciate the beauty surrounding them. This may explain many of the Prophetic hadiths that talk about the merits of planting trees and other acts that benefit people.
Responding to the question, Sheikh Abdul-Wahhab ibn Nasir Al-Tariri, former professor of the Shari `ah at Imam Muhammad Ibn Saud University in Saudi Arabia, states:
There are a number of Hadiths which refer to the issue mentioned in the question. The Prophet (peace and blessings be upon him) is reported to have said, “Whenever Muslims plant a tree, they will earn the reward of charity because of the food that comes from it; and likewise what is stolen from it, what the wild beasts eat out of it, what the birds eat out of it, and what people take from it is charity for them” (Muslim)
The Prophet (peace and blessings be upon him) is also reported to have said,“Muslims will always earn the reward of charity for planting a tree, sowing a crop and then birds, humans, and animals eat from it” (Al-Bukhari and Muslim)
Allah knows best about how this might apply to potted houseplants which are merely kept in the home for decoration and household purposes. Houseplants do not provide the types of general benefit mentioned in the hadith as being the reasons for the reward. The hadith describes the reward for planting a tree to be that of charity. The hadith goes on to describe the charity as being gained through the food the tree provides for humans and animals.
We might extend the meaning of the hadith by analogy to other benefits that plants provide to people, animals and the environment. For instance, trees provide shade along the road and contribute to the beauty of the urban environment. These are important benefits that are enjoyed by the general public. Likewise, trees provide habitation and shelter for birds and many other animals.
However, similar benefits to the public can be likened to charity, but most people keep houseplants at home for beautification, fresh air, and other purely personal reasons. Therefore, we cannot easily extend the hadiths of charity meaning to such plants.
However, we cannot rule out a reward for taking care of such plants. If the houseplant dies without there being fault or negligence on the part of the owner, then there is, of course, no sin upon the owner for its death.
Allah Almighty knows best.
Taken, with some modifications, from www.islamtoday.com