Basil is a well-known herb that is easy for home gardeners to grow. Its leaves smell great and add a lot of flavor to salads, sauces like pesto, and other foods. It is easy and fun to grow basil from seeds so that you can have fresh leaves all season.
When starting basil from seeds, one important thing to think about is how deep to plant the seeds so that they can germinate and grow into seedlings. For most basil seeds, 1/4 inch is the best depth for planting because it gives the seeds the right amount of sunlight and moisture to grow and sprout.
In this detailed guide, we’ll talk about the best depth for planting basil seeds, as well as the best ways to start seeds and take care of seedlings. If you want to grow basil, or if you are an experienced grower looking to improve your methods, this guide will help you plant your seeds at the right depth for a bumper crop.
Why Planting Depth Matters
Basil seeds need certain conditions to germinate, so the planting depth is important. The soil needs to keep the seeds warm, keep them moist, and let them get light.
Planting too deeply can prevent seeds from reaching the soil surface. Basil seeds need light to germinate, so burying them too far down may hinder sprouting.
Conversely, planting too shallowly risks drying out the seeds. Though they need light, basil seeds still require consistent moisture on their seed coats from the surrounding soil to sprout. A very thin layer of soil helps retain that moisture while still allowing light to penetrate.
Finding the right balance by sowing at 1/4 inch enables the seeds to germinate at their highest rate and produce healthy seedlings.
Factors to Consider When Planting Depth
While 1/4 inch is the generally recommended depth across most growing situations, there are some factors that may call for a slight adjustment:
Soil Type
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In heavy clay soils that tend to stay wet, plant a little shallower at 1/8 inch depth.
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In very light, sandy soils that drain quickly, plant a little deeper around 1/2 inch down.
Indoor vs. Outdoor Planting
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When starting seeds indoors, a light sprinkle of soil over seeds is sufficient since you can control moisture and light exposure.
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Outdoors, the 1/4 inch depth helps anchor seeds into the ground securely.
Direct Sowing vs. Transplanting
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If sowing directly into garden beds, aim for 1/4 inch depth.
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When transplanting seedlings outdoors, you can bury the stem deeper up to the seed leaves.
Step-by-Step Guide to Planting Basil Seeds
Follow these simple steps for properly planting your basil seeds at the optimal depth for your growing situation:
Fill starter trays or pots with seed starting mix.
Use a sterile, soilless mix made for seeds. Moisten the mix before planting.
Make holes at 1/4 inch depth in the soil.
Use a pencil or dowel to poke uniform holes 1/4 inch deep. Space 1-2 inches apart.
Place 1-2 basil seeds in each hole.
Gently push seeds into the holes using your finger or a toothpick. Cover with a pinch of soil.
Lightly water the planted seeds.
Use a watering can with a gentle shower head to avoid displacing seeds.
Optional: Cover trays with plastic domes.
This helps retain moisture during germination. Remove once sprouted.
Provide bottom heat and grow lights.
Basil needs consistent warmth around 75°F to sprout. Rotate trays for even light exposure.
Caring for Basil Seedlings
Once your basil seeds are planted at the proper depth, the next key step is providing attentive care to help them thrive:
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Keep soil moist but not saturated while waiting for sprouts.
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Ideally, basil seeds will germinate within 5-10 days when kept at optimal temperatures.
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After seedlings emerge, remove any plastic domes and ensure they receive 12-14 hours under grow lights.
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When the second set of true leaves appear, transplant seedlings into larger containers or garden beds.
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Harden off transplants first by slowly introducing them to more sun and wind over 7-10 days.
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Space transplants 10-12 inches apart in full sun locations with fertile soil and good drainage.
Troubleshooting Germination Issues
Sometimes basil seeds fail to sprout well despite being planted at the right depth. Here are some common causes and solutions:
Seeds Planted Too Deeply: Germination is hampered when seeds are buried over 1/4 inch deep. Sow at a shallower depth.
Soil Too Cold: Optimal soil temperature for basil seed germination is 70°F-85°F. Use a heat mat or wait until soil warms.
Soil Too Dry: Seeds need consistently moist soil to sprout. Water soil before and after planting to keep moist.
Lack of Light: Basil seeds require light exposure to germinate. Plant shallowly or provide artificial light immediately after sowing.
Old Seeds: Basil seeds lose viability after 1-2 years. Purchase fresh seeds from a reputable supplier for best results.
Growing a Prolific Basil Crop
Once your seedlings are successfully transplanted, providing attentive care throughout the season will ensure a bountiful harvest:
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Water regularly to keep soil consistently moist but not saturated. Add mulch to help retain moisture.
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Pinch off any flowers to promote more leaf growth. Prune stems right above leaf nodes.
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Fertilize every 2-3 weeks with a balanced liquid fertilizer or compost tea.
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Check regularly for pests like aphids. Remove by hand or use insecticidal soap spray treatments if needed.
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Harvest often by cutting stems above leaf nodes. Frequent harvesting stimulates growth.
With the right planting techniques, your homegrown basil will thrive this season! Follow these tips to get your seeds started off on the right foot.
Determining the optimal planting depth is an important first step when sowing tiny basil seeds. Aim for a depth around 1/4 inch in most situations to give seeds the right balance of moisture, warmth, and light exposure to sprout successfully. Adjust this depth slightly based on factors like soil type and planting method.
Pay close attention to providing the right growing conditions for seedlings through attentive yet careful watering, ample light, bottom heat sources, and protection from harsh outdoor elements when transplanting. With the proper care, your basil will flourish from seed to harvest.
The Best Soil to Grow Basil
Herbs like basil can be grown almost anywhere, but they thrive in sandy, well-drained soil.
Your native soil is likely a little too thick for the roots of basil to be entirely happy. Should you want to grow basil in the ground, you should either amend the soil or grow it in a pot or raised bed. To amend the soil, simply work in some coarse sand and compost. The sand will improve drainage, and the compost will add important nutrients.
If youre filling a container for basil, mix equal parts organic potting soil, coarse sand, and compost. I like to add a little extra organic matter like earthworm castings. Compost is typically enough to give herbs all the nutrients they need to power their growth, but still. Basil tastes best when its grown in super fertile soil.
Again, make sure your container has at least one good drainage hole in the bottom. It doesnt matter how good your soil is if excess water has no place to go.
Your raised beds are likely already filled with a sandy loam soil thats great for growing herbs and veggies. Just add some compost and maybe some earthworm castings to the surface before you plant more basil.
Basil is super easy to grow from seed. Starting your own herbs from seed means you have more options for varieties than you would if you waited till spring to buy herbs from your local nursery or garden center. Plus, its a much cheaper way to source herbs for your garden. You can also start new basil plants by rooting cuttings (AKA propagating basil, AKA performing plant magic).
The only difficult thing about sowing basil seeds is how tiny the seeds are. Ive found its best to handle them without gardening gloves. I put some seeds in my palm, lick the index finger on the other hand, and try to pick up one seed at a time with the tip of that finger. (It probably goes without saying youll want to have clean hands if you try this!).
How to Transplant Basil Seedlings
Your basil seedlings are ready to be transplanted outdoors when they have about 3 pairs of leaves.
Hardening off your basil seedlings is important. This is a slow process that gets your herbs used to growing outside.
Dig a hole thats as wide as the rootball and a little bit deeper. You can bury your basil seedlings all the way up to their first set of leaves. The stems will actually grow lateral roots if buried, which will help strengthen the plants after their big move.
Overall, herbs like basil grow more vertically than they do horizontally, so you can pack more plants together. But be ready with your garden scissors if you choose to plant intensively. Though the roots aren’t going to take up that much space, the plant will start to spread out and produce tons and tons of flavorful leaves, so make sure you’re harvesting often.
The number of basil plants you can have growing per pot will depend on how large your pot is. Each basil stem should be 3 to 4 inches from its neighbor. If you sow seeds too close together, youll end up with leggy plants. Plants grow leggy, or too tall, when theyre cramped or trying to get more sunlight on their leaves.
This is often the situation when you buy basil plants from the store. They might look like one healthy, bushy plant, but in reality, the grower has over-seeded each pot so that it looks full. If you check the sides, youll notice too many stems coming up side by side. Each of these little plants is competing for water, air flow, and nutrients from the soil. None of them will ever grow to their full potential if you leave them crammed together like that.
Click on the article below to learn how to separate basil plants being grown too closely together.
Start Basil from Seeds & Stop Buying Expensive Transplants: How to Grow Beautiful Basil Plants!
FAQ
How deep do I plant my basil seeds?
Plant the seeds 1/8 inch deep and thin to 3 to 4 inches apart after emergence. The plants germinate in 10-14 days. Irrigate basil with about 1½ inches of water per week. To maintain rapid leaf growth, sidedress with liquid fertilizer every 14 days.
Do I need to soak basil seeds before planting?
Soaking basil seeds before planting is not strictly necessary, but it can help speed up germination. If you choose to soak them, a few hours in warm water is sufficient.
What should you not plant next to basil?
Sage and other drought-tolerant herbs prefer dry soil, which conflicts with basil’s moisture needs. Grown together, they may stunt each other’s growth. Rue and basil are considered antagonistic companion plants.
Can I plant basil seeds directly in soil?
Outdoors – Direct SowPlant seeds about 1/4 “ deep in the soil and about 10-12 inches apart. I’ve grown basil from seeds indoors with natural light and under grow lights, but I think planting the seeds directly outside works best.
How do you plant basil seeds?
Follow these simple steps for proper basil seed planting Fill starter pots or trays with seed starting mix. Moisten the soil before planting. Sow seeds 1⁄4 inch deep, spacing 1-2 inches apart. Gently water the soil after planting to further settle seeds. Cover pots or trays with plastic wrap or dome lids to retain moisture.
How deep do you plant basil seeds?
I plant my basil seeds about 1/4 inch deep in the soil, spacing them roughly an inch apart if I’m using small pots or cell trays. It’s essential not to bury them too deeply because they need light for optimal germination. A cozy temperature between 75°F and 85°F is critical for good germination rates.
How many basil seeds should I plant?
When sowing basil seeds in cell packs, plant 2 to 3 seeds per cell. If starting basil seeds in 4 inch pots, plant 6 to 8 seeds per pot. Whatever type of container you are using for the basil seeds, sow each seed about an inch apart. Plant the seeds a quarter of an inch deep. The exception to this is holy basil whose seeds need light to germinate.
Can you grow Basil from seed?
Basil can be grown from seed or transplants. Plant seeds or transplants after the last frost of the season. Basil seeds germinate best when soil temperatures are 75-85°F and take about 10-14 days to sprout. Plant transplants after the last frost in mid to late May. They need four to six weeks to grow to their full size.
How long does it take for basil seeds to grow?
Basil seeds germinate best when soil temperatures are 75-85°F and take about 10-14 days to sprout. Plant transplants after the last frost in mid to late May. They need four to six weeks to grow to their full size. To keep the soil from drying out, plant the seeds 1/8 inch deep and lightly cover them with soil.
How far apart should Basil be planted?
Water the soil often. Basil grown in full sun has more essential oils and better flavor than shade grown basil. After the seedlings emerge, thin to 3-4 inches apart leaving larger plants. Continue to thin the seedlings until the final plant stand is 12 inches apart.