The amount of light that vegetables and herbs require varies, depending on the type of plant.
We can make most of available garden spaces by observing which areas are in full sun and part shade, both during summer and winter, and then selecting the right plants that will grow best in the available light.
Sun Requirements for Vegetables
To make garden planning easier, we can classify vegetables into three groups, depending on their light requirements.
Vegetables which flower and fruit, such as beans, capsicums, chillies, cucumbers, eggplants, melons, pumpkins, squash, tomatoes and zucchini, well as broccoli and cauliflower, which are the only vegetables that are flowers (the edible parts are referred to as florets). have high light requirements and need a minimum of 6 hours of direct sun (full sun) a day.
Root crops, such as beetroot, carrots, onions and potatoes have moderate light requirements, can grow in slightly less light, and can produce in locations that only receive 4-6 hours of direct sun a day.
Leafy green vegetables, such as lettuce, pak choi, salad rocket (arugula), silverbeet (chard) and spinach have low light requirements, and will grow in part shade, dappled sun, or in shaded locations which only receive 3-4 hours of direct sun a day.
Keep in mind that with fruiting and flowering vegetable, the less sun they receive, the less they will produce. When the available sunlight becomes too low, they will not produce at all!
Sun Requirements for Herbs
Most herbs, especially the aromatic ones with woody stems, need 6-8 hours of full, unobstructed, direct sun each day.
If a garden doesn’t receive full sun,it can still be used to grow herbs, as long appropriate plants suitable for these shady locations.
Some herbs can grow in part shade, with less hours of direct sun. They can also tolerate dappled shade, where sunlight is filtered through tree foliage, and isn’t as intense.
Gardens that don’t receive full sun can grow the following herbs in part shade:
- Lemon balm
- Salad Burnett
- Sweet Woodruff
What is Full Sun and Part Shade?
Plants labels often specify light requirement, referring to full sun or part shade, but what do these terms actually mean?
Full Sun is defined as receiving direct sun for 6 or more hours per day.
Shade defines various degrees of relief from direct sun, and there are four categories of shade, which can be defined as follows.
Light Shade is defined as receiving between 3-5 hours of direct sun in the summer, or where light shade is cast by open-canopy trees during the whole day.
Part Shade (also referred to as partial shade, dappled shade, dappled sun, or semi-shade) is defined as receiving 2 hours of direct sun each day, or being shaded for at least half the day, or where sunlight filters through the leaves of trees to create a constantly changing dappled sun pattern of equal sun and shade.
Full Shade is defined as shade all day, with no direct sun, receiving only reflected, indirect light.
Deep Shade (also referred to as heavy shade or dense shade) is defined as shade all day, with no direct sun, receiving very little reflected, indirect light.
The time of the day that plants receive direct sun does makes a difference, as morning sun is cooler, and less intense than the hot afternoon sun.