Planting a garden is an OUTSTANDING way to do authentic science with students of ANY age (really ages 0-99 on this one!).
It is my view that almost ANY topic can be made to be the basis of any subject OR an entire home school curriculum. For now let's look at how planting, observing, experimenting (all gardening is experimenting!!), and further research could give you a complete science curriculum for ANY age, or even your entire K-12 Science Curriculum if you wanted it to.
Here are some tie-ins to specific sciences:
Astronomy: Planting times, seasons, hours and angles of sunlight, (moonlight can cause some seeds to germinate!).
Chemistry: Nutrients, fertilizers, photosynthesis and respiration, nitrogen fixation.
Geology: Soil, drainage, grade and landscaping.
Meteorology: Weather, precipitation, climate, climate change.
Physics: Phase changes (evaporation, condensation, etc.), thermodynamics, energy transfer, electromagnetic spectrum.
Engineering/STEM/STEAM: There are so many potential projects in the garden that involve engineering and technology: water collection systems, water distribution systems, greenhouses or cold frames, composting systems, etc. And of course plant breeding IS genetic engineering! Over an entire school career, your child could use selective breeding to improve a cultivar of their favorite vegetable!
Biology was too broad a topic so I subdivided it:
Botany: Trees, shrubs, herbs! Every plant there is can be studied in detail!
Genetics: Hybrid vs. Heirloom varieties.
Ecology: Nutrient cycling and energy flow. Your garden IS an ecosystem! Interactions among living things in your garden: pollinators, pests, etc.
Evolution: How human breeding has changed plants from their ancestral forms.
Microbiology: Bacterial component of soil, nitrogen fixation, viral and bacterial diseases of plants.
Mycology: Fungi are CRITICALLY important in your garden!
Zoology: Animals in your garden: insects, mammals, birds.
Hopefully you can see that there is more science related to one garden than can ever be learned in a lifetime: so that's a great starting place for a home school science curriculum if you and your child are interested!
But, that's just science. Can you start to picture how using 'gardening' as a starting point could actually give you an entire home school curriculum if that happened to be something your child was very interested in?
English/Language Arts: Literature, poetry, non-fiction: you will find these things relating to gardens for every age group. Any style of writing can be inspired by the garden: expository, poetry, fiction, a play, anything!
Math: Measurements, calculating area, growing times, size of harvest. At first glance a lot of these ideas seem like they would be pretty elementary. But, there are for SURE more advanced concepts that can be tied to gardening: calculating costs, costs/lb of produce, trigonometry for building projects and mapping out plots, calculus could be used to determine the time it takes for a rain barrel to empty (because the pressure decreases as water is drained, the rate of draining is constantly changing). Many types of measurements could result in good data sets for statistical analysis.
The Arts: View and create art related to gardens/flowers, listen to and create music inspired by nature.
Wellness: Healthy eating, the benefits of being outside and active.
Practical Life Skills: Cooking, building, teamwork.
Service/Leadership: There are so, so many potential projects here. From helping others with their gardens to donating produce or plants to others.
Social Studies was too broad a topic so I subdivided it:
World History: Civilization literally started with agriculture.
US History: Wow! A Google search for "US History + Plants" gets me many results that are well organized and look like great places to start! I am telling you, any topic your child is interested in: you can make it work to teach them just about any subject!
Government/Civics: Maybe start with your local community. What community gardens are around? What local ordinances regulate those? Look at how the branches of government in your state and at the federal level affect agriculture.
Geography: Ranges of plants (think USDA planting zones, but also world-wide). Lots of states have a state vegetable (or herb), fruit, flower, and/or tree. Countries around the world are the same: they might not have a national vegetable, but many have national flowers, trees, and fruits.
Wow, I am actually surprised at how EASY it was to find connections to gardening in every subject I could think of! This approach is possible for just about any subject your child is interested in: have a topic you are stuck on? Email me at firstname.lastname@example.org and I will help you brainstorm!