How much sun does a garden need? Full sun, partial sun, full shade, partial shade … ? These are all terms people throw out, and the truth is, they're somewhat subjective and change depending on many environmental factors. That said, you can follow some basic guidelines to make sense of them and confidently grow a healthy garden.
How Much Sun Does a Garden Need?
Like tiny solar panels, the chloroplasts in plant cells drive growth, and plants have evolved for millions of years to fit their ecological niches. Some have adapted to full sun and hot climates like cacti in deserts, and others have adapted to grow under the shade of thick forest canopies. If you were to take a 'Japanese Painted' fern, for example, and place it in the full sun in Phoenix, Arizona, it wouldn't surprise you that it would be completely burnt to a crisp in no time. Research and experience have taught us the best locations for plants based on how much light they need to thrive.
To make plant selection easier for plant shoppers, seed packets and garden tags provide basic growth information for the thousands of different plants available for purchase. Likewise, online catalogs follow suit and label plants with their general care requirements. These labels tell us everything a plant may need, from how much water it needs and when to feed it to how much sun or shade the plant prefers.
But what exactly do the sun and shade suggestions mean? Let's define each of these terms.
Full sun is just that: Sun for at least six hours per day, with afternoon sun preferred. No trees, buildings or shade of any kind — these plants need the energy from the sun beating down on their leaves all day to thrive.
Full-sun plants typically include many bright, colorful flowers such as echinacea (aka coneflower), sunflowers and marigolds as well as many trees, shrubs and grasses.
Other common plants that are almost exclusively full sun are vegetables. Veggies such as tomatoes, corn and squash all require large amounts of solar energy to produce their large fruits, seeds, leaves and stems. If you want to grow vegetables but your garden gets fewer than eight hours of sun per day, plant small-fruited cultivars. Cherry tomatoes like the 'Sun Gold Hybrid' and ornamentals like this 'Mini Harvest Hybrid Blend' pumpkin assortment have much smaller fruit and might just work with less than ample light.
Partial Sun and Partial Shade
What is partial sun, and how does it differ from partial shade? In general, plants that prefer partial sun are those that require about two to four hours of unobstructed sunlight per day. These are plants that prefer some sun and can usually tolerate the afternoon sun — especially in northern gardens. Common plants might include hostas, lamium and heuchera (aka coral bells).
Likewise, partial-shade plants also require around three to six hours of sun per day but would prefer to be shaded from the afternoon sun. These plants might include 'Ostrich' ferns, pulmonaria and astilbe.
When you see "partial sun" or "partial shade" on the seed packet, just know that too much sun will probably hinder their growth or lead to severe burning.
Although this one might seem to be a no-brainer, plants best suited for full shade still need a fair amount of light — that is, diffused or dappled light. These are the plants that grow wild in ravines, on northern slopes and under the shade of trees. In nature, they often receive a substantial amount of bright, indirect light from the sun, and in gardens, they do best in similar locations.
These locations also receive and hold moisture due to cooler ambient temperatures and lack of evaporation. The northern side of homes without obstructions from trees, for example, is a great spot for shade lovers such as bleeding hearts. The shade trees produce might also be considered full shade, but keep in mind that the tree and anything planted below it will be competing for root space and moisture. Plants such as sedges with their fibrous root systems, such as 'Feather Falls' carex, are great for these conditions. When it comes to shade, you have plenty of options.
Finding plants for the right location in your garden can seem like a daunting task when you begin to consider their sun and shade requirements, but by following what's written on the seed packet or tag, your garden is sure to flourish.