Great question. Normally we know things are alive because they’re doing something like growing or moving, or because they need energy from food or sunlight. Seeds can go for 100 years or more without growing or taking in any energy. (I read an article about some seeds they found in China that were about 500 years old, and some were still able to sprout.) Seeds are still alive, they are just in something like a deep hibernation. The processes are basically “stalled” while the seed is dry. I don’t think they stop completely, but are so rare or slow that it seems that way. This is sometimes called “suspended animation” because it’s like someone hit the “pause” button on the life of the seed. When the seed gets water, the chemicals inside the seed can interact and all of its processes can start happening very fast.

Some animals produce cysts, which are like seeds because they can last for a long time in suspended animation until they are eaten by another animal, or something else happens to re-activate them. There is an animal called the tardigrade that can also use suspended animation to survive harsh conditions after it has started its active life.

Can you think of any drawbacks to using suspended animation?
I really like your question because it shows that people like to make tidy categories for things, but the world is so interesting that it often does not fit neatly into those categories. This happens a lot in biology.

If you are interested in the life of plants, you may want to study botany or plant ecology.

A seed is living. Although seeds are dormant (resting) their cells are still alive and performing typical cellular functions.

Seeds are living! They are just typically in a dormant state, which means they require very little of the resources necessary to stay alive, until they are in the appropriate conditions to grow.

Seeds are living. Inside of a seed is an embryo - a baby plant.

Seeds are fascinating structures. They are definitely living, but are living at a very very slow pace. Imagine that you can slow down your metabolism to an incredibly low rate (you could live for a lot longer...). Seeds are in a dormant state with a very low metabolism and protected by a seed coat from the outside world. Most seeds don't last more than 5 years before the die, rot or are eaten. Some seeds, however, can live for many many years depending on how much energy is stored in the seed. The longest lived seed on record was a date palm seed uncovered in Herod's Palace in Israel (over 2,000 years old). Researchers planted it in 2005 and it sprouted a palm tree! This tree is named Methuselah because of it's old age.