"Land" is not a homestead but it could be considered "agricultural" so it could fall into a couple of different guidelines established by your state and executed by the county where the property is actually located. If you said "land" but you meant home - and the property is your homestead - then the explaination is totally different and the time lines are a little more lieniant.
Different states have different ways they recover taxes but it's either the sale of your deed for an amount equal to the obligation of your taxes plus some additional cost (penality or premium or both) or they sell a superior lien on your property for back taxes plus interest and/or penalty.
The process varies widely from state to state and since you've not indicated where you are located I can give you no specific guidence.
Some states do actually sell your deed and give you as little as 6 months (if the land is not agricultural) to recover it. Some states just sell a lien on the property and within some number of years (set by statute) the lien holder has the right to file for foreclosure. Sometimes there are multiple lien holders for back taxes but the superior lien is the one you have to concern yourself with.
They probably won't foreclose however, read on.
If your property has a mortage on it, the tax lien is superior to the note. Your mortgage company (assuming what you owe them exceeds what you owe in taxes) isn't going to let someone with a minor value-right take the asset (and they lose the right to be paid back - maybe - read your loan, you might still owe the loan even if you lose the property to taxes). The lender is probably going to step in and bid to buy the property away from the tax lien holder But this is still a highly undesirable place to find yourself. You're not off the hook for the taxes. They keep building up and the interest or penalties paid on these liens are in some cases phenominal and can put you in a real bind.
In most cases tax liens are purchased by investors. Really, they just want a return on their investment. They will eventually foreclose on your property if they have to to get their investment back - but most would rather get their target return on investment.
More than how long you have, it's costing you a fortune. In the state you're in however, you may have paid the maximum penalty at the time the lien or deed was sold. So it might not matter (from an interest rate stand point) whether you pay it back immediately or wait a while.
You can't sell your property until the liens are paid (they are usually cleared at closing) but this is less money for you on the property.
Sorry I can't help you specifically without knowing which state/county you're in.