What a plant actually needs
What does a plant really need to grow?
A plant never shops or eats a sandwich. So what keeps it alive?
It sits in one spot all its life. Where does it get what it needs?
Your family’s shopping list goes on and on.
A plant’s list is much shorter. It fits on one small note.
Here is the whole list: light, water, air, food, and warmth.
Look what is missing. Soil is not on it.
Leaves catch light and take in air through tiny holes.
With light, air, and water, a leaf makes its own sugar. That sugar gives the plant energy.
- A · light
- B · tiny air holes
- C · vein bringing water
Roots drink water. The water climbs up the stem to every leaf.
Without enough water, the plant droops.
A plant also needs tiny bits of food from outside. Roots take them in with water.
These bits of plant food are called nutrientsTiny bits of plant food that roots take in with water.
See it in the glossary.
- A · light
- B · air
- C · water
- D · nutrients
Last on the list is the right warmth. Too cold, and most plants grow slowly or stop.
Too hot, and they lose water faster than roots drink it, so they wilt.
Your turn. Pack the plant’s bag.
Put each thing in the right pile. Does the plant need it?
Does the plant need it?
Tap a card, then a bin. Or press 1 or 2 on a card.
- Nothing here yet
- Nothing here yet
Does the plant need it?
The answer:
Needs it
- Light Leaves use light to make sugar.
- Water Roots drink it, and it climbs up to the leaves.
- Air Leaves and roots both take in air.
- Nutrients These bits of food help the plant build new parts.
- Warmth In the cold, most plants grow slowly or stop.
Can do without
- Soil Roots can find water and food without it.
- Sugar water A plant makes its own sugar in its leaves.
- A name Naming a plant is fun. The plant doesn't need it.
Check 1 of 3
Which of these is on a plant's shopping list?
Show the answer
Light. Right. Leaves use light to make their own sugar.
Check 2 of 3
Where does a plant get its sugar?
Show the answer
It makes sugar in its leaves. Right. Leaves use light, air, and water to make it.
Check 3 of 3
A plant gets light, air, water, and warmth. It gets no nutrients. What happens?
Show the answer
It grows slowly and looks pale. Right. Without nutrients, it can't build healthy new parts.
You just learned the short list of what a plant needs.
Next up: What soil does, and what it does not do.
Go deeper: the full listOpenClose
Leaves take in carbon dioxide from the air through tiny pores called stomata. They give off oxygen.
The sugar-making process is called photosynthesis. Light energy turns carbon dioxide and water into sugar.
Roots need air too. They take in oxygen from the air spaces in soil, or from air in the water.
Scientists list 17 elements that plants must have. Nickel was the last one added, so some older books list 16.
Plants get carbon, hydrogen, and oxygen from air and water. The other 14 come in through the roots as nutrients.
Carbon, hydrogen, and oxygen make up about 94 to 95 percent of a plant’s dry matter. Books differ slightly on the exact figure. So most of a plant is built from air and water, not soil.
Cool-season crops such as lettuce grow best in cooler weather. Warm-season crops such as tomatoes need more warmth, and frost can damage them. Seed packets and extension guides give ranges for each crop.
Sources
- Moore, K. A., and L. K. Bradley, eds. "3. Botany." North Carolina Extension Gardener Handbook, 2nd ed. NC State Extension, AG-831, 2022. Link
- VanDerZanden, A. M. Vegetative Plant Parts. EM 9904. Oregon State University Extension Service, 2008 (reviewed 2024). Link
- Gatiboni, L. "1. Soils & Plant Nutrients." In Moore, K. A., and L. K. Bradley, eds. North Carolina Extension Gardener Handbook, 2nd ed. NC State Extension, AG-831, 2022. Link
- Jones, C., and K. Olson-Rutz. Plant Nutrition and Soil Fertility. Nutrient Management Module No. 2, 4449-2. Montana State University Extension, 2016. Link
- Liu, G., E. H. Simonne, and Y. Li. Nickel Nutrition in Plants. HS1191. University of Florida IFAS Extension. Link
- Cogger, C. A Home Gardener's Guide to Soils and Fertilizers. EM063E. Washington State University Extension, 2014 (revised 2020). Link
- Kaiser, C., and M. Ernst. Hydroponic Lettuce. CCD-CP-63. Center for Crop Diversification, University of Kentucky College of Agriculture, Food and Environment, 2016. Link
- Lehigh County Master Gardeners. Cool-season vs. Warm-season Vegetables. Penn State Extension, 2024. Link
- Steil, A. What's the difference between cool and warm season veggies? Yard and Garden, Iowa State University Extension and Outreach, 2025. Link