When I began planning my winter garden last summer, I was determined to correct my previous mistake. My summer plants did not grow as vigorously as they should have due to the poor quality of my soil. They all suffered from fungal rot and a few produced fruit half-heartedly. I prefer the greens and cruciferous vegetables of winter over summer squashes and tomatoes anyway, so I was eager to get my broccoli, kale, lettuce, Swiss chard, garlic, and carrots in the ground.
One hot July day, I chose an area with full sun and covered the existing grass with cardboard and aged manure, which I watered if it became too dry. Later, I pulled the grass, weeds, and removed rocks and added more organic material, mainly composted yard waste. I made a border of fallen branches because I intend to build this bed layer by layer from all organic materials. Finally, I made mulch of fallen leaves to cover my beautiful, beautiful dirt, and then carefully planted my carrots and parsnips. I buried garlic bulbs and I transplanted my tiny broccoli and kale plants from my indoor hydroponic garden.
But, I forgot to consider where the sun would be positioned come the winter solstice. The sun rises and sets two houses down the street now, which is south from the summer sun path, which passes almost directly over my house. My winter garden is shaded for the entire morning by neighboring houses and trees.
The plot receives a few hours of direct sunlight in the afternoon, and this may end up being okay, but I am feeling quite dumb forgotten having forgotten that the sun’s path becomes shorter and lower in the sky as we approach the winter solstice.
I’m sure I learned about how seasons work in school. I’m sure I was quizzed on the tilt of the earth’s axis, solstices, equinoxes, and why these celestial pivot points matter. I know that light in September feels different, as it slants just so and sharpens the hazy lines of late summer. But, this escaped me as I planned out my winter garden last July. So now, as I had to get down to basics with soil science, I need to learn how the sun works.
What is the Sun’s Day Arc?
The Sun’s daily path, or day arc, is the apparent motion it traces across the sky from an observer’s fixed point on Earth. Each day begins with the Sun rising in the east and ends as it sets in the west, following a curved trajectory. On the spring and autumn equinoxes, the Sun rises precisely in the east and sets directly in the west, creating a perfectly balanced arc.
During the winter solstice, this arc is at its shortest and lowest, resulting in the year’s shortest day. From that point forward, the arc gradually lengthens, climbing higher in the sky with each passing day until it peaks at the summer solstice. This marks the longest day of the year, with the Sun tracing its highest, widest arc. After the summer solstice, the process reverses, with the arc shrinking and lowering each day until it returns to its smallest, lowest point at the next winter solstice. This rhythmic pattern is a constant, graceful reflection of Earth’s orbit and tilt.
The solstice and equinox are key astronomical events that mark the changing seasons, rooted in the Earth’s tilt and orbit around the Sun.
A solstice happens twice a year, around June 21 and December 21, when the Sun reaches its most northern or southern point relative to the equator. During the June solstice, the Northern Hemisphere experiences its longest day and shortest night, signaling the start of summer.
Conversely, the December solstice brings the shortest day and longest night, marking winter’s arrival. These extremes occur because the Earth’s axis is tilted 23.5 degrees, positioning the Sun directly over the Tropic of Cancer in June and the Tropic of Capricorn in December.
An equinox, occurring around March 20 and September 22, is when the Sun is directly above the equator, resulting in nearly equal day and night lengths across the globe. The March (or vernal) equinox ushers in spring in the Northern Hemisphere, while the September (autumnal) equinox marks the beginning of fall.
Unlike solstices, equinoxes occur when neither hemisphere is tilted toward the Sun, creating a balance in daylight hours.
What is Sun Mapping?
Sun mapping is the practice of observing and tracking the patterns of sunlight and shadow in your garden or outdoor space over time, or at least seasonally. It is creating a map of how light moves through your space, helping you understand where the sun shines brightest, where shadows linger, and how these patterns change throughout the day and across seasons.
It’s the foundation for smart garden planning because different plants have different light needs—some thrive in full sun, while others prefer partial shade or dappled light. Without knowing your space’s light dynamics, it’s easy to plant something in the wrong spot and watch it struggle.
The insights you gain can guide not just where you plant, but also where you place seating, paths, water features, or even that dreamy wildflower meadow you’ve been imagining. It’s about working with the natural rhythms of your space rather than fighting them.
At its core, it’s about slowing down and paying attention to what the sun is doing each day and each season. You can make it as sophisticated and precise as you need to.
How to Map the Sunlight in Your Garden
Sketch Your Garden Layout
Start by drawing a rough map of your garden. Be sure to include every permanent feature that might influence sunlight and shade, such as fences, walls, trees, buildings, sheds, or even tall shrubs. These elements cast shadows at different times of the day and can drastically affect your planting plans.
Label the Cardinal Directions
Mark north, south, east, and west on your map. This is crucial for visualizing how the sun moves across your garden. In the Northern Hemisphere, the sun rises in the east, arcs across the southern sky, and sets in the west. Understanding this path will help you predict light patterns, especially during seasonal shifts.
Track the Light
Make several copies of your layout or use tracing paper over your original map. Over the course of a sunny day, observe and record which parts of your garden are in full sun, partial sun, or shade.
- Check at regular intervals. Many suggest every 2-3 hours.
- Use color coding to mark sunny, partially sunny, and shaded areas.
- Take photos or videos if you prefer a visual record. If you have outdoor cameras, reviewing the footage is a simple way to study light patterns without having to be outside all day.
Once you’ve tracked sunlight over a full day, the patterns will start to emerge. You’ll notice which areas get the most consistent light, which are shaded by mid-afternoon, and where dappled sunlight filters through trees. Over time, this map will also reveal seasonal shifts as the sun’s angle changes.
How Much Sunlight Do Plants Need?
In addition to soil and moisture, optimizing sunlight is critical to plant health and fruit development. Most food gardens require at least 6-8 hours of sun per day. In the northern hemisphere, where I am located, a south-facing garden receives the most sun.
Full Sun (6+ Hours of Direct Sunlight)
These plants thrive in bright, unfiltered sunlight for most of the day. Perfect for areas that bask in direct rays from mid-morning to late afternoon.
Part Sun (4-6 Hours of Direct Sunlight)
These plants need at least 4 hours of direct sunlight daily but can also handle some shade in the morning or afternoon. They often prefer some protection from the hottest midday sun.
Part Shade (2-4 Hours of Direct Sunlight or Dappled Light)
These plants tolerate or even prefer a mix of light and shade, especially in hot climates. Morning sun combined with afternoon shade works well.
How Can I Tell If My Plants Are Getting Enough Light?
Plants have subtle (and not-so-subtle) ways of letting you know if their light needs are being met. Here’s what to look for:
Signs Your Plants Are Getting Enough Light
- Healthy Growth: Plants grow steadily, with vibrant leaves and strong stems.
- Color Consistency: Leaves maintain their natural color without fading or turning yellow.
- Flowering and Fruiting: Blooming plants produce flowers, and fruiting plants set fruit as expected.
- Compact Form: Stems and leaves are tight and bushy, rather than stretched or leggy.
Signs Your Plants Need More Light
- Leggy Growth: Stems grow long and thin as the plant stretches toward light.
- Pale or Yellowing Leaves: Insufficient light can cause leaves to lose their rich green color.
- Slow Growth: The plant seems to stop growing or grows very slowly.
- Dropping Leaves: Lower leaves may fall off as the plant prioritizes new growth closer to the light source.
- Failure to Bloom or Fruit: Flowering or fruiting plants may struggle to produce
How Can I Increase Sunlight in My Garden?
Start by positioning tall plants, like sunflowers or corn, on the north side of your garden bed. This ensures they won’t cast shade over shorter crops, which should be placed to the south. This layout helps all your plants soak up their fair share of rays.
For vining plants like tomatoes, cucumbers, and beans, vertical structures such as trellises or arbors are your best friends. Not only do they elevate plants toward the sun, but they also create partial shade below, which helps keep the soil cooler and prevents it from drying out too fast.
Reflective surfaces are another clever way to boost sunlight. Mirrors, aluminum foil, or even light-colored walls can bounce extra light into shaded corners of your garden. Place these surfaces strategically along fences or walls to brighten up spots that might otherwise miss out.
If your garden faces the opposite problem—too much sun—a shade cloth can provide relief. This specialized fabric filters sunlight, creating a cooler microclimate for heat-sensitive plants. For instance, tomatoes often stop producing fruit when temperatures exceed 85ºF, but shade cloth can help lower plant temperatures enough to keep them thriving.
I’ll Follow the Sun
When I created my own sun map, I was surprised to discover how the light shifted dramatically with the seasons. The far side of my backyard, completely shaded in summer, turns out to be ideal for a winter garden.
My current plots, which bask in the summer sun, lose their light by late fall—but, as the trees shed their leaves, they let in more sunlight. Yes, here in mid November, most of my trees still have their leaves! And no plant is ever a waste of time or space in your garden. Any plant at all is better than nothing in terms of soil health.