If you have ever walked through the University of Arizona campus in Tucson, you may have passed some of Arizona's most famous science experiments without knowing it. In the 1890s, Robert Forbes, who later became director of the university's College of Agriculture, planted 295 olive trees to find out whether Mediterranean plants could survive Arizona's dry climate. According to the University of Arizona Campus Arboretum, those olive trees still shade walkways like John E. Rogers Way, and each fall volunteers harvest their fruit so it can be pressed into oil instead of going to waste.
Olive harvest time is a big deal around the state. When FOX 10 visited Queen Creek Olive Mill, it called the harvest "a signature annual event." So this is a perfect season to ask your kids the same question Forbes asked more than a century ago: what does a plant need to thrive in the desert?
It's also a busy season for Arizona homeschoolers. KOLD reported that more than 108,000 students now use Empowerment Scholarship Accounts, and parents are trading ideas at curriculum swaps, with one planned in Pinetop this November. If you're looking for a hands-on science unit to add to your plans, this one grows right on your windowsill.
What your kids will learn
Grades K–5
- Some plants can grow from a piece of another plant, not only from seeds
- The jobs of stems, leaves and roots
- How to observe, measure and draw a plant's changes over time
- How to care for a living thing with water, light and patience
Grades 6–12
- Asexual propagation: why a cutting grows into a genetic copy of its parent tree
- How rooting hormones (auxins) help a stem form new roots
- Plant adaptations: how olive leaves are built to save water in a dry climate
- Planning a fair test, controlling variables and recording data in a science journal
This week's activity: the desert olive investigation
Think of this as your family's own version of the Forbes experiment. Part one needs nothing but a little observation. Part two is where the growing begins.
- Find an olive tree. Olive trees are planted in many Arizona yards, parks and campuses. Look closely at a leaf (with permission if it isn't yours). Notice how narrow, thick and silvery-gray it is underneath.
- Compare leaves. Pick up a fallen olive leaf and a fallen leaf from a thirsty, broad-leafed plant. Have kids draw both and describe the differences in size, thickness and color.
- Make a hypothesis. Why might a narrow, waxy, silver-backed leaf help a tree survive the desert? (Hint: less surface for water to escape, and a lighter color that reflects sun.)
- Study a pit. Rinse a pit from a store-bought olive your family has already eaten. Measure it, sketch it and talk about how it protects the seed inside.
- Plan a fair test. If you were Robert Forbes, what one thing would you change to see what helps a young olive plant grow? Soil type? Water? Sunlight? Write down which one thing you will change and what you will keep the same.
- Run it. Plant two cuttings in two different growing mediums, keep everything else the same, and check them every few days. Record any new leaves, and gently look for roots when your instructions say it's time.
Not every family has an olive tree to take a cutting from, and that's where our Olive Tree Cutting Rooting Science Kit comes in. Each kit includes a real olive tree cutting (about 4 inches long), rooting powder, step-by-step rooting instructions, and curriculum and worksheets for your child's grade band, emailed after purchase. Choose the add-on and you also get a second cutting, two peat pots and two different types of soil, which is exactly what you need for step 6's side-by-side test.
Want to go deeper into the "what does a plant need?" question? The Soil Science Experiment Kit (4 Pots) lets kids compare traditional potting mix with coconut coir using fast-sprouting seeds, with sprouting typically starting in 3–7 days. It comes with four peat pots, both growing media, two seed varieties, five lessons and a side-by-side growth tracking chart, so kids see quick results while their olive cutting takes its time.
Join the growing community
Every kit comes with an invitation to our Facebook group, "Aardvark's Seed Planting For Little Hands," where kids and parents can get support with anything they need. Post a photo of your olive cutting's first new leaf, share your leaf drawings, and swap tips with other young growers, from Tucson and Phoenix to the West Virginia hills and the Arkansas Ozarks. Every result your child shares helps another young scientist learn.
Start your own desert olive experiment
Arizona's olive trees began as a question. Give your kids the chance to ask their own:
- Olive Tree Cutting Rooting Science Kit – Grow an Olive Tree from a Cutting, with Curriculum & Worksheets: $19.00 for the kit, or $29.00 with 2 pots, an extra cutting and 2 growing mediums. Choose Grades K–5 or 6–12.
- Soil Science Experiment Kit (4 Pots) – Compare Growing Media, with Curriculum & Worksheets: $39.90. Choose Grades K–5 or 6–12.
