Plant food: the nutrients and what each one is for

Students will

• Explain that nutrients are building blocks a plant takes in through its roots.
• Name nitrogen, phosphorus, and potassium, and give one job for each.
• Explain that a plant needs some nutrients in big amounts and others in tiny amounts.

New words

nitrogen

A nutrient that helps a plant grow big, green leaves.

phosphorus

A nutrient that helps roots grow and flowers bloom.

potassium

A nutrient that keeps the whole plant strong.

Talk about it

Your dinner plate has different foods for different jobs. How is a plant's plate like yours, and how is it different?

Check questions and answers

1. A plant's oldest leaves turn pale first. Which nutrient might be low?

   • Nitrogen (answer) Right. Nitrogen helps a plant grow big, green leaves.
   • Calcium Not quite. Calcium helps build firm new growth. Think about green leaves.
   • Iron Not quite. Iron trouble shows on new leaves first. Think about old ones.

2. Why does a plant need more than one nutrient?

   • Each nutrient does a different job (answer) Right. Like foods on a plate, each one helps in its own way.
   • One nutrient can do every job Not quite. Think about the plate. Each helping does something different.
   • More kinds make the water look nicer Not quite. Nutrients are for the plant, not for looks.

3. Which nutrient does a plant need only a pinch of?

   • Iron (answer) Right. A plant needs only a tiny bit of iron. It still matters.
   • Nitrogen Not quite. Nitrogen is one of the big helpings.
   • Potassium Not quite. Potassium is one of the big helpings.