Seeds & Greetings

Seeds and Greetings

Growing Basil Indoors

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Seeds and soil: Start with high-quality, organic seed starting soil and a packet of organic basil seeds.  

Pots: You can use ordinary 10-12" pots for growing indoors. If your soil is consistently moist and warm, your plants will be happier, healthier and will grow faster. Ensure proper drainage and be careful not to over water to avoid root rot. 

Bright lights and warm temperatures: Basil thrives in a warm, bright location, such as a south-facing window that is sunny for most of the day. If you don't have a suitable window, use LED grow lights to grow robust, healthy plants anywhere in your home or office. Basil seeds germinate best when soil temperatures are 75-85°F. Seeds take 7-14 days to sprout after planting.

Planting Basil Seeds Indoors: Lightly moisten fresh, organic potting mix and pack firmly into 10-12" pots, or larger for indoor plants. Pour some seeds into your palm, and sprinkle the soil surface with a few seeds. Cover the seeds with a thin layer of soil and press gently to firm the soil. Water gently or use a mister to moisten the soil.

Place in a warm window with a southern exposure. Avoid drafty windows, or locations where temperatures drop considerably at night. As the plants grow, rotate the pots to keep them from leaning in one direction, toward the light. If you are using grow lights, set a timer so that they are on for 14 hours a day. Place the lights a few inches above the seedlings.

Tips for caring for basil indoors:
Keep the soil moist, but not soaking wet. Over watering basil can cause root rot.

If the plants start to look crowded as they grow, use scissors to thin them out. Snip the extra seedlings at the soil line and enjoy them in a salad.

Raise grow lights as the plants grow. If the plants look leggy, move the lights closer. If you see white spots on the leaves, the lights are too close.

A month after planting, you can enjoy the aroma of basil by running your hands over the small leaves. Two months after planting, you may have enough basil leaves to make fresh pesto! If the leaves start looking pale green in color, start using liquid fertilizer, mixing at the rate recommended on the package. For continuous harvests, plant a batch of seeds every few weeks.

Beyond Pesto: UMass researchers show some basil varieties serve as pharmacies for pollinators

The organic seeds we’ve sent you in our holiday card this year are of the Genovese variety, which is the most commonly used basil in Western cuisine. Genovese basil is what you are likely to find in pesto or pizza Margherita. 

Genovese is just one of basil’s many forms. Other varieties may challenge your expectations of what basil should look and taste like. For instance, cinnamon basils are known for their distinct purple leaves and a unique flavor profile that is reminiscent of anise or cinnamon. Lime basil has a tree-like growth habit and smaller leaves, with a scent and flavor dominated by, you guessed it, citrusy tones. The Greek Dwarf variety looks more like a miniature topiary bush than a basil plant, and its flavor composition is similar to Genovese, but more pungent. 

Next growing season, be adventurous and try these strange varieties in your outdoor garden! You might also be doing your backyard bumble bees a favor. Research by the Adler Lab at UMass has shown that Cinnamon, Lime, and Greek Dwarf basil have medicinal effects against Crithidia bombi, a widespread bumble bee parasite that is especially prevalent in the northeastern US. Infected bees that fed on these basil varieties had lower parasite loads than bees that fed on two Genovese varieties. 

The key to helping pollinators is to let some of your basil plants flower. Bees cannot benefit from this medicinal effect if they don’t have any basil flowers to snack on. This will shorten the longevity of your basil plants, but you’ll be rewarded with a ton of seeds to plant for the next year!

With Lynn Adler, professor of biology as his PhD advisor, Sean Clemente is studying eastern bumble bees and Crithidia bombi, a common bumble bee gut parasite that can reduce the reproductive rate and colony founding success of queen bees, while impairing learning and foraging efficiency in worker bees. The goal is to determine whether certain types of basil, such as cinnamon basil and lime basil, have medicinal properties that can help ailing bee populations recover. Read more about UMass research on basil varieties that show medicinal properties for pollinators.

Starting Basil Seedlings: Tips from Sean Clemente, UMass PhD Candidate

If planting outside, it is best to start basil seedlings indoors no later than late-April to allow time for seedlings to grow before transplanting outdoors. 

1. Prepare a seedling tray, or several small flowerpots (4” – 6” diameter pots are recommended). You may also use small plastic cups with ½” diameter holes punched through the bottom for drainage.
2. Fill the tray or pots with commercial organic potting soil.
3. In each seedling tray cell or pot, create a ¼ inch-deep depression with your index finger. 
4. Place 3-4 basil seeds in each depression. Using your fingers, cover each depression with soil so that they are level with the rest of the soil. If planting many seeds at once, use a moist Q-tip to pick up several seeds at once. Dislodge them with a flat object, such as a plastic card. 
5. Using a spray bottle, wet the soil. (You may also use a watering can, but water gently so that the seeds are not flooded out of the container.)
6. Keep the seedling tray or pots in a warm, humid area – no colder than 70º F. Check daily to see if the soil is moist. Use a spray bottle or watering can to re-moisten the soil as needed. You may encourage a moist environment by keeping the seedling trays/pots in a humidity dome. You may also cover the trays/pots with plastic wrap. If using plastic wrap, remove once the seeds have germinated.
7. Allow the seeds to germinate – this will take about 7 days. Once the seedlings have four leaves, winnow them out so that each cell or pot only has one seedling. Seedlings are easily removed by gently pinching the stem and pulling up. 
8. After winnowing, keep seedlings watered by generously using a spray bottle or using a watering can.
9. Once the seedlings are 2–4” tall and have several sets of leaves, they are ready for transplant. Transplant them to larger containers for indoor planting. Or, if transplanting outside, wait until after last spring frost, around mid-May for most of Massachusetts. To transplant, simply dig a hole deep enough to bury the plant’s roots and mound soil around the base of the stem for support. 
10. As basil plants grow larger, they will start to flower. Remove inflorescences (flower spikes) as they appear. Allowing basil plants to set seed significantly reduces their longevity. Prune leaves as needed.
11. If growing indoors, the ideal pot size for mature plants should be no less than ¾ gallons. 
12. If growing outdoors, allow basil to flower near the end of the growing season (late August). Leave flowers alone—they will develop into seed pods. You can collect seeds from mature seed pods for the next growing season. If you'd like, save some seeds to donate to the UMass Amherst Mass Aggie Seed Library.