Here is a fun fact to share at the dinner table: if your family eats a salad anywhere in the United States this winter, there is a good chance the lettuce came from Arizona. Yuma County grows roughly 90 percent of the country's leafy greens between November and March, according to a FreshFreight report on the Yuma produce season. Yuma farmer and Arizona Farm Bureau president John Boelts told Agri-Pulse in September that his November lettuce was already planted and he was planting for December harvest.
So right now, while much of the country is putting gardens to bed, Arizona's low desert is heading into its biggest leafy green season. Why does lettuce love an Arizona winter? Mild days, cool nights and lots of sunshine.
That last ingredient, light, is something your kids can test for themselves at home this week, no farm required.
What your kids will learn
Grades K-5
- What plants need to grow: light, water and air
- How a seed sprouts and grows its first leaves
- How to measure seedlings with a ruler and keep a daily growth journal
- What happens to seedlings when they get more or less light
Grades 6-12
- Photosynthesis: how plants turn light energy into food
- Phototropism, or why seedlings bend toward light
- Etiolation: why seedlings with too little light grow tall, pale and leggy
- Designing a controlled experiment with one variable and graphing the results
This week's activity: the Lettuce Light Test
You need a packet of lettuce seeds (any variety), two small pots or cups with drainage holes, potting mix and a ruler.
- Plant two identical cups. Fill both with the same potting mix and sprinkle about ten lettuce seeds on top of each. Lettuce seeds sprout best with some light, so press them in gently and cover them only very lightly.
- Choose your variable. Put one cup in your brightest indoor spot, like a south-facing window. Put the other in a dim corner of the same room, away from windows. Same water, same temperature, different light.
- Predict. Ask your kids which cup will sprout first, which will grow taller, and which will look healthier. Write the predictions down.
- Water the same way. Keep both cups evenly moist with a spray bottle or a small measured amount of water each day.
- Measure and observe. Every day or two, count sprouts, measure the tallest seedling in each cup, and note the color of the leaves. Do the dim-corner seedlings lean or stretch?
- Graph it. Younger kids can draw two growing bars. Older kids can make a line graph of height over time for each cup.
- Taste the winner. After a few weeks, snip the healthiest baby leaves for a tiny homegrown salad. Rinse them first, and only eat what you planted yourself.
Don't be surprised if the dim cup grows taller at first, with seedlings that are pale and floppy. That result is called etiolation: the seedlings stretch as they search for light. It is a great conversation starter about why light matters.
Build a real indoor grow lab
A windowsill works, but window light changes with the weather and the time of day. The LED Grow Light Plant Stand Science Kit gives your kids two lighted shelves where they control the light themselves, which makes the experiment much more precise.
- A two-shelf grow light stand, 26.5 inches tall by 28 inches long by 12 inches wide
- Two 2 ft, 10-watt full-spectrum LED light bars mounted 10 inches above each shelf
- Grade-level curriculum and worksheets for K-5 or 6-12, emailed after purchase, covering photosynthesis, phototropism and how to design an experiment that changes the hours of light per day
Each shelf holds one standard 10 × 20 microgreens tray. Trays and seeds are sold separately, and some assembly is required. Kids can grow lettuce on the top shelf and compare it with the bottom shelf, or run the same seeds under different light schedules.
Need seeds to fill those shelves? The Heirloom Vegetable Seed Science Collection includes 30 heirloom varieties and more than 5,000 seeds, including Mixed Green Lettuce and Long Standing Spinach, plus its own curriculum on plant families, germination trials and seed saving. It is our most popular kit, and the extra varieties can go straight into your low-desert garden this season.
Join the growing community
Every kit includes an invitation to Aardvark's Seed Planting For Little Hands, our private group where families share photos, ask questions and troubleshoot experiments together.
Post your bright-cup and dim-cup results. Young growers in Arizona, Arkansas and West Virginia are all experimenting this month, and it is fun for kids to see that while some of them are watching frost, Arizona kids are just getting their greens going.
Start your winter greens lab
- LED Grow Light Plant Stand Science Kit – $168.99
- Heirloom Vegetable Seed Science Collection – 30 Varieties, 5,000+ Seeds – $85.95
Get the LED Grow Light Science Kit
Plant a few seeds this week, and your kids can grow greens indoors right alongside the Yuma lettuce harvest.
