Land is only considered a zakatable asset if it was bought with the intention of resale. In such a case, it would be considered business inventory and zakat would be due on its value every year on one's zakat date. However, if the land was bought for farming, cultivating, residing, etc. (as seems to be the case in your query), then it would not be a zakatable asset. If a person decides to sell the property later on, zakat will only be due on the cash proceeds that remain in their possession on their zakat due date.  Therefore, zakat will only be due on the money you had in your possession on your zakat due date after selling your house.