Garden Sun Mapping: How to Know Which Parts of Your Garden Get Sun

Why sun mapping matters for your garden

Every plant has specific light requirements. Tomatoes need at least 6 to 8 hours of direct sun per day. Lettuce can thrive with just 3 to 4 hours. Hostas and ferns prefer shade. If you plant sun-loving vegetables in a spot that only gets 2 hours of direct light, they will grow leggy, produce poorly, and disappoint you no matter how good your soil and watering habits are. Sun exposure is not just one factor among many — it is often the single most important factor determining whether your garden thrives or struggles.

In urban and suburban gardens, buildings are the primary determinant of sun exposure. Your house, your neighbors' houses, garden walls, fences, and nearby apartment buildings all cast shadows that move across your garden throughout the day. A spot that is sunny at 10 AM might be in deep shadow by 2 PM. Understanding these shadow patterns — and how they change across seasons — is the foundation of successful garden planning.

Many gardeners learn this the hard way, planting an entire bed of tomatoes in a spot that turns out to get only morning sun before the neighbor's garage casts its afternoon shadow across the whole area. Sun mapping your garden before you plant saves time, money, and frustration.

Understanding full sun, partial shade, and full shade

Gardening guides use standard terms to describe light conditions. Full sun means at least 6 hours of direct sunlight per day. Partial sun or partial shade means 3 to 6 hours of direct sun. Full shade means less than 3 hours of direct sunlight, or dappled light filtered through tree canopy throughout the day.

But these definitions need nuance. Six hours of gentle morning sun from 7 AM to 1 PM is very different from six hours of intense afternoon sun from noon to 6 PM. Morning sun is cooler and less intense, which is ideal for many leafy greens and herbs. Afternoon sun is hotter and more drying, which suits heat-loving plants like peppers and eggplant but can stress moisture-loving plants.

The timing of sun exposure also matters for plant health. Plants that get morning sun dry their leaves quickly after overnight dew, which reduces fungal disease risk. Plants in morning shade that only get afternoon sun stay wet longer and may be more prone to mildew and other moisture-related problems.

When mapping your garden, note not just the total hours of sun but also when those hours occur. A bed that gets sun from 8 AM to 2 PM is a different growing environment than one that gets sun from noon to 6 PM, even though both receive 6 hours of direct light.

How buildings affect your garden's sun

In most residential gardens, the house itself is the biggest shadow-caster. A two-story house on the south side of a garden will cast a shadow that extends well into the garden, especially from October through February when the sun is low. Even in summer, the early morning and late afternoon shadows from the house will shade parts of the garden that are sunny at midday.

Neighboring buildings matter just as much. A tall apartment building to the south or southwest can shade an entire small garden for most of the day in winter. Even a single-story garage or shed on a neighboring property can block crucial hours of low-angle winter sun that would otherwise reach your raised beds.

Fences and walls have a subtler but significant effect. A 2-meter garden wall on the south side casts a shadow of about 7 meters in midwinter but less than 1 meter in midsummer. This means the planting area immediately north of a south-facing wall is a seasonal sun trap — warm and bright in summer, cold and shaded in winter. Understanding how building shadows work across seasons applies directly to garden planning.

Trees add another layer of complexity. Deciduous trees block sun in summer but let it through in winter when their leaves have fallen. An area shaded by a large deciduous tree in July might be in full sun in January. Evergreen trees and hedges, by contrast, block sun year-round. Consider whether each shadow in your garden is seasonal or permanent when planning your beds.

Mapping your garden through the day and seasons

The traditional method of sun mapping is to observe your garden at hourly intervals on a clear day, noting which areas are in sun and which are in shade. Mark sunny areas on a sketch of your garden at 8 AM, 10 AM, noon, 2 PM, 4 PM, and 6 PM. Areas that are sunny in most observations are your full-sun zones. Areas that are sunny in only a few are partial shade. Areas that are never sunny are full shade.

The problem with this approach is that it only tells you about one day. The sun's path changes dramatically across the year. A spot that gets 8 hours of sun on June 21 might get only 2 hours on December 21 because the sun is lower and building shadows are much longer. To truly understand your garden's sun profile, you need data for multiple times of year.

The most important dates to check are the summer solstice (around June 21), the winter solstice (around December 21), and the equinoxes (around March 20 and September 22). The solstices show the extremes — maximum and minimum sun exposure. The equinoxes show the middle ground, which is roughly representative of the growing season's average conditions. If you are planning a vegetable garden, the period from April through September is what matters most, so focus on the spring equinox through the summer solstice range.

What to plant where based on sun exposure

Once you have mapped your garden's sun zones, you can match plants to their ideal conditions. For full-sun zones receiving 6 or more hours of direct light, plant tomatoes, peppers, squash, beans, cucumbers, eggplant, corn, and most fruit trees. These plants need abundant light to produce fruit and will disappoint in partial shade.

For partial-shade zones getting 3 to 6 hours of sun, plant lettuce, spinach, kale, chard, peas, radishes, herbs like parsley and cilantro, and root vegetables like carrots and beets. These plants actually benefit from some shade protection, especially from intense afternoon sun in summer. Many leafy greens will bolt to seed quickly in full hot sun but produce beautiful harvests with just a few hours of direct light.

For full-shade zones receiving less than 3 hours of direct sun, your edible options are more limited but not zero. Mint, chives, and some varieties of lettuce can grow in surprisingly low light. Ornamentally, shade gardens can be stunning with hostas, ferns, astilbes, and woodland flowers. If you only have a shady garden, consider raised containers that you can position in the sunniest spots, or grow shade-tolerant crops like mushrooms.

Using Coffee in the Sun to map your garden

Coffee in the Sun makes garden sun mapping dramatically easier. Instead of spending an entire day observing shadows — and then repeating the process in different seasons — you can check the shadow situation for your garden at any time and any date, all from the app. Find your garden on the map and use the Time Travel feature to scrub through the day. Watch the building shadows move across your garden and note which beds receive sun at which hours.

Check multiple dates to understand the seasonal range. Compare the midsummer shadow pattern with early spring and late autumn. You will likely discover that parts of your garden that seem permanently shaded in winter open up to generous sun in the growing season — and vice versa. This information lets you plan your planting with confidence, putting the right plants in the right spots for optimal growth. For anyone interested in finding the sunniest outdoor spots, the same principles that help you find a sunny terrace apply perfectly to planning the sunniest garden beds.