Updated: Sep 15, 2022
This herb is both aromatic and delicious – and makes for a yummy addition to any pasta. Originating from tropical Asia, basil is actually a member of the mint family and one of the easiest herbs to grow with a few easy steps. From sweet basil to lemon basil, and everything in between, this annual herb grows well in warm climates and everything from large containers to garden beds. I even grow some just next to a sunny windowsill.
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Some basil terms worth knowing
Before I get started on how to grow basil from seed, let’s learn a little bit about basil itself
It’s all in the name! When you trim your basil plants for harvest, they produce new growth, replenishing your source of delicious basil leaves!
The bundle of soil and roots of a plant that’s being transplanted from a small pot to a garden or a larger pot.
Types of basil
When it comes to this herb, there are quite a few basil varieties to choose from! Some are better for pesto, while others can enhance vinegars or even refreshing lemon basil surprise. If you really want to impress (or confuse) your friends, you can call it by it's latin name ocimum basilicum. Message me if you can actually say that 3 times fast - I still can't!
This group includes the standard bushy plants and Globe varieties (Spicy Globe and Green Globe). These varieties grow shorter, rounder, and more bush-like (hence their name!). They have smaller, textured foliage.
This group includes varieties like Napoletano, Miden- ette, and Romanesco. These are the common basil plants that you’re probably most familiar with! They have larger, deep green leaves and a sweet basil aroma.
Known for its purple basil to bronze foliage. This group includes Dark Opal, Emerald Wine and Rubin varieties, and are usually decorative or used for vinegars.
This Italian variety is one of the most common and popular. Its large, dark green leaves are some of the best for making pesto. Plants of this variety grow to be about 18-24 inches tall.
This variety hails from Mexico and carries the same chemical found its namesake spice, giving it a distinct cinnamon-like scent. It has dark leaves ranging from green to almost brown with purple stems and pink flower buds.
Also called Anise or Licorice basil, Thai basil has a distinct spicy flavor. Its leaves are also smaller and more narrow than other varieties, and are more heat tolerant when being cooked. The undersides of the leaves are purple, along with its stems and flower buds. This variety is great to grow for teas and vinegars.
Starting basil seeds
How to grow basil from seed
Keep in mind that basil is most successful when it’s directly sown, and don't do as well when transplanted. If growing indoors, start them in larger containers so they can grow from seed to harvest.
It’s ideal soil temperature for germination is between 65-85°F (18-29°C), and basil doesn’t tolerate frost at all – so any threat of frost should be totally gone before you plant or move it outside. If starting indoors, heat mats can work wonders.
It’s also very important to control any weeds during the germination and seedling stages, because basil doesn’t compete well.
Basil needs full sun (for their ideal nutrient and oil level) and it also prefers soils that are rich and well-draining.
Considering all these factors, once you plant your seeds, you can set them about a quarter inch deep every 4 inches, keeping their rows about 12 inches apart.
Once they’re planted, lightly firm the soil, then wait - your seeds should germinate in about 1-2 weeks!
Caring for basil
In this section, I’ll cover everything you need to know about soil preparation, how to properly water your basil, thinning, and the benefits of mulching. I’ll also talk transplanting, companion planting, as well as your growing structure options!
PREPARING YOUR SOIL
First, you’ll want to find a spot in full sun with rich, well-drained soil that’s free of any weeds.
It’s also important that this spot can ensure good air circulation around your basil plants.
They like rich soils, so adding organic matter to your garden bed ahead of planting will also make your basil very happy! Just add 1 inch of decomposed compost to your garden bed, blend it into the top 6 inches of your soil, then level your soil with a rake.
You can plant your seeds about a quarter inch deep every 4 inches, keeping rows about 12 inches apart. Once they’re planted, lightly firm the soil around them. Your seeds should then germinate in about 1-2 weeks.
WATERING YOUR BASIL
Make sure you water your basil immediately after planting or transplanting.
You’ll want to keep the soil moist, not wet, throughout the growing period - but especially during germination. Moist soils will prevent your plant’s leaves from wilting in hot temperatures, which is what you want to avoid!
When your soil is too dry, it also puts stress on the plant and roots, causing premature flowering.
On average, basil plants need about 1 inch of water per week. Just avoid overhead watering, because it can encourage fungal growth.
Basil is prone to various bacterial and fungal diseases, so it needs to have excellent air movement around its leaves and stem.
After your seeds have sprouted, thin your Basil seedlings so that there’s 8-10 inches (20-25cm) between each plant, keeping only the healthiest ones.
You can also thin up to 12 inches (30cm) apart if you want to be extra careful.
Basil is a cut-and-come-again plant, so when you remove flowering branches throughout the growing season, it helps promote growth and branching.
This will result in larger, fuller basil plants, and we would recommend doing this every 2-3 weeks.
Not sure if you’ve overwatered your basil? Typically, yellow and drooping leaves are the first sign that your basil has had too much water!
FERTILIZING AND/OR MULCHING
How to grow basil from seed with environmental support
We recommend supporting your basil with nitrogen fertilizer. Basil seedlings won’t need it, so you can actually feed your plants when they are about 3-4 weeks old using a diluted solution of an indoor houseplant food.
When plants are mature (and have 6-8 leaves), you’ll want to fertilize them every 2-3 weeks using a diluted liquid nitrogen fertilizer.
For best results, be sure to follow the manufacturer’s instructions.
As for mulch, it can be added to your garden beds and planters to help control weeds, retain soil moisture and moderate soil temperatures.
Aged wood chips or grass clippings are great options to use for herbs like your basil. Simply spread the mulch onto your garden beds after transplanting, or after seeds have germinated and Basil seedlings are established.
Just make sure to keep any mulch away from the stems of your plants, so that you can prevent any rot from taking place.
GROWING BASIL STRUCTURE OPTIONS
You can Grow basil in a variety of spaces, but these are the most common in any horticulture focused crop growing and sustainability adventure.
Basil can be successfully grown in garden beds, raised beds and containers. It doesn’t like to be crowded, so growing in containers is an excellent choice!
Basil is prone to damping off, so just be sure to thoroughly clean your containers before planting.
You can also leave them in direct sun to kill any bacteria or fungus that may be growing on their surface! Once you’re ready to plant, you’ll want to use sterile soil and well-draining containers.
To improve your soil’s drainage, simply put some rocks and smaller stones at the bottom of your planter - then add soil on top.
You can also drill some small holes into the bottom of your planter if it doesn’t already have any. Just be careful, and keep in mind that some materials may not be drill-able!
TRANSPLANTING BEST PRACTICES
How to grow basil once you have a seedling or transplant
If you’re sowing indoors, sow basil seeds in rich, sterile potting soil, and cover them with a quarter inch of soil.
Keep the soil moist and between 65-85°F (18-29°C). Then, your seeds should germinate within 1-2 weeks! Once sprouted, you’ll want to move your seedlings to a spot that gets a lot of light.
You can transplant your seedlings about 6-8 weeks after sowing them indoors, once there’s no longer any threat of frost. You’ll want to make sure the air and soil temperature requirements are met too!
But wait – make sure you harden-off your basil plants first! Before transplanting into your garden bed, keep your seedlings outdoors for a week, in a spot where they’ll be sheltered from any wind and/or hot sun. This will help prepare them for transplant, and reduce any shock once they’ve been relocated.
If there’s any threat of frost or cold weather, make sure you move your seedlings back indoors for the night. Basil is definitely a warm climate plant that needs a full 8 hours of sunlight to thrive. (although they will happily grow under a sunny grow light )
Ready to transplant? Here are a few growing tips
STEP 1: Prepare moist soil just as you would for direct sowing, by loosening the top 6-8 inches and adding in some organic matter.
STEP 2: Dig some holes that are both 10-12 inches apart and deep enough so that the root balls of your basil plants are completely covered. Carefully remove your basil plants from their containers, then ever-so-gently loosen their root balls to encourage root anchorage in their new soil.
STEP 3: Lightly firm the soil around the base of the plant and then immediately give it a drink. Remember to keep the soil moist (but don’t over water!) to keep your plants from wilting.
STEP 4: You can add mulch to your garden beds to prevent weeds from germinating, but be sure to keep it away from the stems and leaves of your basil plants.
BASIL COMPANION PLANTS
How to grow basil from seeds with it's plant friends
Basil companion plants:
Growing your basil together with tomatoes improves both of their flavors!
Marigolds are another great option, and will help protect your basil! They produce chemicals that repel whiteflies and root-knot nematodes - both of which like to feast on your basil. Marigolds also attract parasitoid wasps, which feed on any other potential pests.
Peppers, asparagus, and root vegetables (most veggies, really) benefit from growing close to basil for its ability to repel pests like flies, aphids, asparagus beetles and mosquitos.
Finally, flowering herbs like oregano, chamomile and chives improve the oil content in basil leaves, enhancing their flavor.
Rosemary: this herb requires dryer conditions than basil, so it shouldn’t be grown in the same soil.
Rue and sage: aside from chamomile, chives and oregano, avoid planting basil with other aromatic herbs to keep their flavors pure. Rue also suppresses basil’s growth.
Some gardeners advise keeping your basil separate from cucumbers, which have a very high water content and can adopt a similar flavor to basil if planted too close.
If you’re growing your basil outside, it’s best to plant it with eggplant, beets, peppers and asparagus!
Common challenges and their solutions
Basil doesn’t compete well, so make sure you stay in control of weeds. Also, there are quite a few pests and diseases that can potentially threaten your basil plants.
How to grow basil plants from seed or plant, free of pests
Aphids are small, wingless, warm weather pests that leave a transparent substance called honeydew on your plant’s leaves. They feed on young plant growth, which deforms the leaves and invites other pests to join the feast. In small numbers, aphids aren’t a major concern - just make sure to thoroughly wash your basil leaves before consuming them.
In large numbers, though, aphids are a greater threat. You can discourage them by companion planting with members of the carrot family! These will attract predatory insects that feed on aphids, like parasitic wasps and ladybugs. Insect soaps can also be used to get rid of aphids on your basil.
These beetles pose a particular threat for east coast gardens. They feed on leaves and create lots of holes. Not only does this reduce your plant’s ability to photosynthesize, it also provides wounds where disease can enter.
In order to limit Japanese beetle populations, you’ll want to use succession planting and insect netting.
These are small insects that spread viral disease and cause spotted leaves. They are very tiny, wedge-shaped, and lightly coloured. Insect soaps and neem products are both effective ways to prevent and eliminate these pests.
These are microscopic worms that, for the most part, don’t cause any problems. They can however hurt your plant’s roots and prevent them from taking up water and nutrients. This will cause discoloration, your basil will wilt, and its yields will be low. No good!
By adding organic matter to your soil, you’ll boost populations of beneficial, predatory micro-organisms that can prevent a harmful nematode outbreak.
Slugs are nocturnal and feed on basil leaves. Once they’ve had their midnight snack, they leave holes and slimy trails behind. Wet conditions encourage them, so although it’s important to keep the soil moist, it’s just as important not to overwater your plants.
Also, be sure to keep your basil in warm sunlight, avoid overhead watering, and keep any organic waste away from your plants.
These pests are known for their white bodies and wings, and for hanging out on the undersides of leaves. They feed on the leaves, causing damage that makes the plant susceptible to other diseases.
Sticky fly traps can be used to control an outbreak, as well as insect soaps and predatory wasps.
How to grow basil from seed or plant without diseases
Discolored, brown-streaked, or twisted stems are all big indicators of this disease. Abrupt leaf drop is another typical symptom you’ll notice. Fusarium wilt often won’t show itself until plant growth is in the mid to late stages, and sweet basil seems to be the most susceptible to it.
Just how it sounds, this disease impacts the root system of your plants. It attacks young seedlings, causing slow or rapid wilting and shriveling of the stem. Roots become too severely damaged to function properly, and your young plants will often die as a result.
Infected plants will have gray to brown colored mold growing on their leaves and stems. Gray mold is distinguishable from downy mildew by its fuzzier appearance, and it’s also a lot heavier on your plant. Infected leaves will eventually die and drop, and entire plants can die if their stems are affected.
At first, Downy Mildew causes leaves to turn yellow, typically starting from the main vein then spreading outward. The disease will then cause fungal spores (ew!) to grow on the undersides of leaves, appearing as gray to almost purple fuzzy spots.
You’ll notice irregular and moist dark spots on the leaves of your plant, and streaks on the stems. Blight doesn’t usually harm established basil plants, but it can definitely be damaging to your seedlings.
Plant certified disease-free seeds when possible. Seed packets often identify these right on the package. If you're not sure, ask your garden centers team, I'm sure they'd love to help you understand the different varieties of basil.
Use drip watering methods, or any watering method that focuses on only watering the base of your plant. You want to avoid splashing your plant, and make sure you also keep its leaves nice and dry.
Also, ensure good ventilation and air movement by keeping your plants at least 8-10 inches apart (up to 12 inches is good). This will also help reduce any humidity around your plants.
Remove and destroy any diseased leaves.
Rotate your crop placement – so, if you have an affected area in your garden, avoid planting in that spot again for 2-3 years.
If you’re planting in containers, make sure you clean them thoroughly before planting! This ensures that any bacteria or fungi are killed.
To prevent Downy mildew, you can also spray your plants with a 40:60 solution of milk and water. Simply spray your plants every 10-14 days if the weather becomes hot and humid.
Fusarium wilt is actually one of the most common basil diseases! There’s no remedy for it either - if you’ve got it, you’ll have to destroy any affected plants.
Harvesting and storing
How to grow basil from seed or plant for your plate
The best part about basil? It’s a cut-and-come-again plant – so after you harvest, your basil will grow back! Keep in mind that you’ll want to harvest pairs of leaves from alternating plants, so that you allow your basil more time for regrowth.
Before you begin harvesting, it’s important to note that you’ll want to use scissors or a similar tool to ensure the stem gets a clean break. Any tearing or damage to the stem can act as a gateway for disease.
You can begin harvesting once your basil plant has 6-8 leaves, but be sure to only remove enough of the stem so that about 4 leaves remain. Technically, you can cut off as much as half the plant in a single harvest if you like - though this can stress the plant and it may reduce its productivity in the future.
FOR FRESH USE
You’ll want to cut just before eating. If you’d like some short-term storage, you can also put basil cuttings in a jar of water (away from direct sunlight) for more fresh eating!
FOR LONG-TERM STORAGE
Cover the jar, stems, and leaves with a plastic bag then keep it in your fridge.
You can also preserve basil leaves by tying bunches together and hanging them upside down in a dark place to dry, which should take 5-10 days. Or, you can dry them at 150-200°F for 3-5 minutes in your oven.
In general, dried basil leaves keep for about one year when they’re stored in an air-tight jar in a dark place.
You can also freeze whole basil leaves in ice cubes, and they’ll keep for 3-6 months. This method of freezing is a better way to preserve that yummy basil flavor!
Make sure you keep your basil away from the sun!
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