Basil is one of those lush, aromatic plants that add spice and flavor to not only your kitchen but your garden! The basil you see typically growing in the garden is considered sweet basil (Ocimum basilicum L.), but the Ocimum genus contains around fifty different species known for their culinary, medicinal, or ornamental qualities!
Basil is super easy to grow, and it loves the heat. But what if your garden is a little on the shady side? Will this spicy annual thrive without full sun?
In this article, we examine the ideal amount of sunlight exposure for basil, and if your it will grow to its fullest potential while being grown in the shade.
Nothing beats the taste of homegrown basil on your caprese salad or margherita pizza. With its heady aroma and bold flavor, this leafy herb is a must for any gardener. However, achieving optimal growth requires meeting basil’s picky preferences – especially when it comes to light.
Understanding basil’s light requirements is key to harvest after abundant harvest. Read on to learn exactly how much illumination your plants need at each stage to become vigorous producers. We’ll also cover troubleshooting lighting issues and using supplemental lighting to keep basil flourishing indoors and out.
Light Needs of Basil Plants
Originally hailing from sun-drenched India, basil is decidedly a light-loving plant. It thrives on a minimum of 6-8 hours of direct sunlight daily. With insufficient light, you’ll end up with puny, stunted growth and sparse leaf production.
Seedling Stage
Basil seeds need warm soil temperatures of at least 70°F to germinate Once sprouted, the young seedlings require 14-16 hours under grow lights or bright sunlight Position lights 2-4 inches above the plants.
Vegetative Growth Stage
Once basil plants reach 3-4 inches tall, you can move them into the garden or a permanent pot. Place them where they’ll get 6 or more hours of direct sun. Dappled shade in the afternoon is beneficial in extremely hot climates.
Flowering/Fruiting Stage
If allowed to flower and set seed basil needs increased light levels – up to 10-12 hours of sun per day. However most growers pinch off flowers to prolong leaf production.
Outdoors, situate basil where it will receive sun from mid-morning through early afternoon. A south-facing site is ideal. Shelter from hot midday sun will prevent leaf scorching in summer.
For indoor basil, situate pots right next to a sunny, south-facing window. Turn the plant frequently so all sides get exposure.
Signs of Insufficient Light
Without adequate illumination, basil slows photosynthesis and struggles to grow. Watch for these indicators:
- Smaller leaves
- Pale yellowish leaves
- Long spindly stems and sparse foliage
- Leaves cupping or curling
- Flower buds failing to open
- Leggy, weak growth unable to support itself
Using Supplemental Lighting
Natural outdoor light can be challenging to control. Take advantage of supplemental lighting to customize optimal conditions for your basil plants:
Grow Lights – Use LED or fluorescent grow lights to provide 14-16 hours of light for starting seeds and growing basil year-round indoors. Position the plants 4-8 inches from the bulbs.
Reflectors – Place reflective mulch, white paint, or small mirrors around plants to maximize sun exposure and bounce light undersides of leaves.
Light Extenders – Use plastic sheets, cloches, cold frames, or row covers to trap heat and light in the spring and fall.
Shade Cloth – In midsummer, 30-50% shade cloth prevents leaf scorch but still allows adequate light penetration.
Light Meters – Use a light meter to assess illumination levels and identify ideal planting spots getting 6+ sunlight hours.
Troubleshooting Lighting Problems
If your basil leaves are small and pale or stems become elongated and weak, lack of sufficient light is likely the culprit. Take these corrective steps:
- Move potted plants right up against a sunny window.
- Add a grow light or switch bulbs to brighter, full spectrum LEDs.
- Find a new garden location receiving more direct sunlight if possible.
- Prune backleggy growth so the plant can refocus energy on new foliage.
- Whitewash greenhouses or use shade cloth to increase light intensity on plants.
- Use reflectors or reflective mulch to maximize light exposure.
- Thin surrounding plants to reduce competition for sunlight.
Be aware that other issues like overwatering, high temperatures, and inadequate nutrition can also cause spindly basil growth. Address all cultural conditions for the healthiest plants.
Ideal Light Conditions for Growing Basil
Follow these tips to successfully grow basil in optimal light:
- Select full sun sites with 6-8 sunlight hours, ideally facing south.
- Shelter potted plants from hot sun using shade cloth or patio umbrellas.
- Start seeds indoors under grow lights or in a greenhouse/cold frame.
- Gradually acclimate seedlings before moving them outdoors.
- Use shade cloth or filtered light in midsummer to prevent leaf burn.
- Keep indoor plants actively growing with 14-16 hours of supplemental light.
- Rotate pots frequently to ensure even exposure on all sides.
- Monitor outdoor light patterns and plant timing accordingly.
- Avoid reflected heat damaging plants by walls or pavements.
- Watch for signs of insufficient light like small leaves and leggy stems.
Keep Basil Thriving through All Growth Stages
Basil is highly responsive to proper care at every point in its lifecycle. Tailor light levels and meet all other cultural needs, and you’ll be rewarded with abundant harvests. Here are some tips:
Germinating Seeds
- Start seeds indoors 6-8 weeks before your last frost date.
- Use warm bottom heat and grow lights for best germination rates.
- Cover seeds lightly with 1/4 inch of fine soil or seed starting mix.
- Maintain constant 70-80°F soil temperature and even moisture.
Transplanting Outdoors
- Harden off seedlings for 7-10 days before transplanting.
- Transplant on a cloudy day or in late afternoon to avoid stress.
- Space plants 12-15 inches apart in full sun.
- Use row covers to boost warmth and light for tender plants.
Throughout the Season
- Pinch off flower buds to prolong leaf production.
- Fertilize every 3-4 weeks with a balanced liquid fertilizer.
- Monitor for pests like aphids on undersides of leaves.
- Harvest outer leaves frequently, leaving the growing center intact.
Let the Light Shine on Your Basil
Basil is easy to grow when you meet its exacting requirements for ample sunlight. Take steps to maximize light exposure at all stages with smart siting, supplemental lighting, and troubleshooting fixes. Then get ready to harvest more mouthwatering basil than you can imagine!
Will Basil Grow in Shade?
Yes… and no. It is recommended that basil is not grown in full shade (less than 1 hour of direct sunlight per day). Partial sun or partial shade means that the plant receives 2 to 6 hours of sunlight per day. Partial sun usually implies the plant likes more heat or is okay with more sun, while partial shade means the plant prefers cooler temperatures or less sun.
For basil, partial sun (3-6 hours of sunlight) is better than full shade, but the best spot for basil in your garden is in full sun (at least 6 hours of sunlight per day). In very hot, dry areas, it may be better for basil to be in partial sun to reduce wilting. This doesn’t mean you can’t experiment! Try growing basil in different spots in your garden to see what works best for you.
There are seven different elements that are important to consider when growing basil. These items are seasonality, location, soil, pinching, moisture, mulching, and fertilizing. Let’s look at each in a bit more detail.
Unlike other perennial vegetables that return each year, Basil is a tender herbaceous annual in the Lamiaceae (mint) family. ‘Annual’ means the plant completes its life cycle in one year, meaning it will start from a seed, then flower, and produce seed within one year. ‘Herbaceous’ implies that the stems are not woody. Basil has similar sunlight needs to mint, being in the same family.
‘Tender’ indicates that this plant is frost sensitive (though sweet basil is hardy to USDA Zone 10). You can get a jumpstart in the garden by starting seeds inside, but otherwise, you must wait until after your last frost in order to plant out in the garden. There are some places, like the Mediterranean region, that basil can be grown as a short-lived perennial.
Basil is mostly grown in climates with temperatures from 45 to 80 degrees F. Most commercial production of basil in the U.S. takes place in the southern and southwestern states. The climate is favorable for a heat-loving plant in those locations.
Basil prefers well-draining soil. Well-draining soils are typically light soils with high amounts of sand or silt. Heavier soils (or soils with large amounts of clay) can be remediated by additions of organic matter (i.e. compost or well-rotted manure) to improve drainage qualities.
Basil loves water. A steady supply of water throughout the growing season is critical due to this plant being prone to water stress. Water the soil beneath the plant leaves rather than over the top of the leaves to reduce the prevalence of diseases.
Mulching can help reduce water stress, as it reduces water evaporation from the soil surface. As long as the plants receive ample moisture, mulching may not be necessary. Another benefit to mulching, however, is that it can help suppress weed growth.
To encourage lateral growth, the basil plants can be pinched when they are approximately 6 inches in height. Pinching is accomplished by snipping off the top portion of a plant just above a set of leaves. This causes the lateral buds to grow new branches, producing a shorter and leafier plant.
To fertilize basil, use a well-balanced fertilizer that has equal parts nitrogen (N), phosphorus (P), and potassium (K). To accomplish this, you may try applying a mixture of fish emulsion and seaweed extract, or you can choose a synthetic fertilizer like 10-10-10. After the first harvest, applying a fertilizer with higher nitrogen (like blood meal) can be applied to promote regrowth of the plant.
Quick Tips For Growing Basil
To grow basil, you will start your basil from seeds, whether inside or in the garden. Only bury the seeds about ¼” for optimal germination. Make sure your soil or seed-starting mix is moist until germination.
Basil can also be propagated by cuttings, but for the first-time grower, it may be much easier to start from seed. If you’d like to try to grow from a cutting, snip the plant just above a leaf node (where the leaves attach). Then, pull off the lower leaves of your cutting. Place the stem in moist soilless media (seed-starting mix, perlite, vermiculite, or potting mix).
Cover the plant with clear cling wrap or something similar (try cutting off the top of a water bottle!). This will help to keep in humidity. Then place the plant in a shaded, warm location until roots start to form on your cutting.
Commercially, basil is planted 6 inches apart in rows that are 24 to 36 inches apart. In raised bed systems, basil is typically grown at a spacing of 12 inches by 12 inches. Spacing will depend on your garden and your use of basil. In my garden, I like to plant my basil in rows that are 4 feet wide with a spacing of 9 inches by 9 inches. This has worked out well for my purposes, but you can plant as close as 5 to 6 inches apart!