Vegetables and Direct Sun
Understanding the specific sunlight needs of vegetables is crucial for any gardener aiming to cultivate a thriving garden. This comprehensive guide, grounded in horticultural research, delves into the essential light cycles, definitions, and the importance of direct sunlight for various vegetables. Tailored to address the concerns and curiosities of avid gardeners, the chart below provides a detailed list of sunlight requirements for commonly grown vegetables, ensuring you have the knowledge to create the most conducive environment for your plants to flourish.
- Gardening Definitions for Sun and Shade
- Hours of Sunlight Chart
- Hydroponic Considerations
- Frequently Asked Questions
Gardening Definitions for Sun and Shade
Navigating the nuanced definitions of full sun, full shade, and partial sun or shade can be a common source of confusion for many gardeners, as these terms dictate the vital sunlight exposure that plants require to photosynthesize effectively, grow, and remain vigorous. To clarify this ambiguity, we have chosen to align with the Penn State Extension’s precise definitions, ensuring that you have a clear framework to understand the light conditions in your garden before selecting plants. This understanding is essential, as the amount of light a plant receives is a primary determinant of its health and productivity.
Full Sun:
Full sun refers to receiving six hours or more of direct sunlight throughout the day that is either continuous or not continuous. This means that the sunlight doesn’t have to be uninterrupted—it can be split, such as four hours in the morning and another three or four in the afternoon, with a period of shade in between.
Partial Sun:
Partial sun refers to areas that receive direct sunlight for approximately four to six hours each day, typically either in the morning or the afternoon. This level of sunlight is sufficient for many plants, particularly those that can thrive without constant exposure to intense midday sun.
Partial Shade:
Partial shade conditions are characterized by limited direct sunlight, receiving about two to four hours per day, often during the cooler parts of the morning or late afternoon. These areas are typically sheltered from the intense midday sun, which is beneficial for plants that require a cooler, less intense light environment.
Shade:
Shade areas receive less than two hours of direct sunlight each day, often with filtered light during the remaining daylight hours. These conditions are well-suited for plants that can thrive without direct sun exposure and need protection from the intensity of full sunlight.
Hours of Sunlight Vegetable Chart
| Vegetable | Type of Sun | Direct Sunlight Minimum | Direct Sunlight Preference |
|---|---|---|---|
| Artichoke | Full Sun | 6 hours/day | 6 – 10 hours/day |
| Arugula | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Asparagus, Seed | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Asparagus, Crown | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Celtuce | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Bean, Bush | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Bean, Lima Bush | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Bean, Lima Pole | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Bean, Pole | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Bean, Scarlet Runner | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Bean, Yardlong | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Beet | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Belgian Endive (Witloof Chicory) | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Black-Eyed Pea (Cowpea, Southern Pea) | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Bok Choy | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Broccoli | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Brussels Sprout | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Cabbage | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Cabbage, Chinese | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Carrot | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Cauliflower | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Celeriac | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Celery | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Chard, Swiss | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Chicory (Endive, Escarole) | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Chicory, Italian Dandelion | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Chive | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Collards | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Corn, Sweet | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Corn Salad (Mâche, Feldsalat) | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Cress | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Cucumber | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Edamame | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Eggplant | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Fennel (Finocchio) | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Garbanzo (Chickpea) | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Garlic | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Horseradish | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Jerusalem Artichoke (Sunchoke) | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Kale | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Kohlrabi | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Leek | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Lettuce, Head | Tolerates Partial Shade (but grows well with full sun in Spring and Fall) | 4 – 6 hours/day | 6 – 8 hours/day |
| Lettuce, Leaf | Tolerates Partial Shade (but grows well with full sun in Spring and Fall) | 4 – 6 hours/day | 6 – 8 hours/day |
| Muskmelon (Cantaloupe) | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Mustard Greens | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| New Zealand Spinach | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Onion, Set | Full Sun | 6 hours/day. Green onions will grow with 5 hours of sun per day. | 8 – 10 hours/day |
| Onion, Seed | Full Sun | 6 hours/day. Green onions will grow with 5 hours of sun per day. | 8 – 10 hours/day |
| Parsley | Tolerates Partial Shade/Partial Sun | 4 – 6 hours/day | 6 – 8 hours/day |
| Parsnip | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Pea | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Pepper | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Potato | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Pumpkin | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Radicchio | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Radish | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Rutabaga | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Salsify | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Shallot | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Spinach | Tolerates Partial Shade (but grows well with full sun in Spring and Fall) | 4-6 hours/day | 6-8 hours/day |
| Squash, Summer | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Squash, Winter | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Sweet Potato | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Tomatillo | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Tomato | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Tomato, Ground Cherry (Husk Tomato) | Full Sun | 6 hours/day | 8 – 10 hours/day |
| Turnip | Tolerates Partial Shade/Partial Sun | 4-6 hours/day | 6 – 8 hours/day |
| Watermelon | Full Sun | 6 hours/day | 8 – 10 hours/day |
Hydroponic Considerations
In hydroponic systems, understanding and managing light exposure is vital, whether grown outside, where your plants are influenced by natural conditions, or indoors, where the environment is meticulously controlled. While outdoor hydroponics depends on the natural light cycle (and can utilize the above chart), indoor systems require the grower to tailor light duration and intensity, simulating natural days to suit various plant requirements. This controlled approach is key to maximizing growth and productivity in an indoor hydroponic setup.
Trying to Mimic the Sun
While attempting to replicate the sun’s capabilities is crucial in hydroponics, it’s important to realize that indoor growing isn’t about simply duplicating direct sunlight, but rather emulating the entire natural daily light cycle, including both direct and indirect light exposure. Take cabbage, for instance: it requires a minimum of 6 hours of direct sunlight outdoors. In an indoor hydroponic setup, however, you should aim to provide not just 6 hours, but a full day’s worth of light to more closely mimic the natural environment.
Bearing this in mind, here are a few essentials you should know before growing inside.
- Utilize full-spectrum LED lights to provide the necessary blue and red light frequencies.
- Mimic natural conditions with about 12 to 16 hours of light (for most plants) and the remaining hours in darkness.
- Remember that the dark period is especially important for initiating the flowering stage.
- Employ an electric timer to maintain this cycle consistently, ensuring your plants receive the optimal light for their development stage.
Different Plants Have Different Needs
Understanding plant photoperiodism—how plants respond to lengths of day and night—is fairly important in hydroponics and can dictate how long you should keep your grow lights on. Long-day plants require short nights to flower, thriving with extended light exposure. Short-day plants need longer nights to trigger flowering, favoring shorter daylight. Day-neutral plants, however, flower regardless of light duration.
Managing light schedules in your hydroponic system is crucial for mimicking these natural cycles and optimizing plant growth and flowering stages.
- Long-day plants in hydroponics: Long-day plants typically require more than 14 hours of light per day to initiate flowering, necessitating careful light cycle management to simulate extended summer daylight hours.
- Short-day plants in hydroponics: Short-day plants generally need less than 12 hours of light to trigger flowering, making it essential to simulate shorter daylight periods, akin to autumn or winter, for optimal growth.
- Day-neutral plants in hydroponics: day-neutral plants aren’t dependent on specific light durations, flowering regardless of day length, allowing for a more flexible lighting schedule typically ranging between 12 to 16 hours.
Frequently Asked Questions (FAQs)
Where did the chart information come from?
The chart was primarily built from individual plant profiles from the University of Maryland Extension. However, to complete the list, we also used information from University of Florida IFAS Extension, Cornell University, Clemson College of Agriculture, Forestry, and Life Sciences, University of Delaware, Penn State Extension, LSU Ag Center, PSU Plant Village, and Utah State University.
Are there other charts similar to this?
Yes, we have many charts on Ponicslife.com that are helpful. Try reading When to Transplant and Harvest Vegetables: A Complete List, Seed Planting Depth and Spacing Chart for Vegetables: A Quick Guide, and the Seed Germination Time and Temperature Chart.
How exact is the chart?
The chart above comes from reliable academic sources. However, as discovered when writing this article, there are different definitions and occasionally different numbers depending on the academic source. As a gardener, just remember to use this as a general guide and do your own trial and error. Gardening is as much an art as it is a science.
I bought my plant and it says something different?
As described above, different sources are occasionally going to say different things and have different definitions. If the label of your plant says something specific, go with the label and use this article/chart as a general guide.
Can vegetables grow in indirect sunlight?
Some vegetables can tolerate indirect light but may not thrive as they would in direct sunlight. Use the above information as a guide.
What if my garden doesn’t get enough sun?
Consider shade-tolerant vegetables or move inside and use artificial lighting to supplement. You can also relocate your garden to a more favorable spot if room permits.