Growing Basil Indoors: Tips for a Showstopping Harvest Summer or Winter!

Basil is an incredibly prolific plant, the rate of growth is absolutely astounding under the right conditions!

Here at 3WAH, we use a ton of basil; we love making spaghetti, unique pasta dishes, marinara sauce, pizzas, savory Italian casseroles, and SO much more.

I dare you to make some homemade marinara sauce after using our methods to grow basil inside… you will be transported into a slow, easy going mid-summer’s afternoon in your grandmother’s kitchen, just drooling over the world’s most tender, juicy meatballs, as she prepares them for an early supper.

If you take a peek into our pantry, you would think that we’re Italian; although I’m not, having an Italian influence in my teenage years could have played a small part in this…

Nonetheless, Basil is incredibly important here, and you can easily underestimate your need for fresh basil. So, what do you do when it’s late in the growing season, or even in the autumn or winter season, when you run out of basil?

Simple! You grow your basil seeds indoors in pots in windows, or hydroponic setups under lights. You would be amazed at how much basil you can grow from the comfort of your home!



Growing Basil Indoors: Tricks to Planting and Harvesting Healthy Basil During Summer, Fall, and Winter in Windows or Under Plant Lights!

Lengthy title, yes.

That’s because we have a LOT to cover, y’all!

Growing basil from seed to harvest, with several different methods under varying growing conditions, takes some time to present. Now, I want every reader to succeed, and I want to make sure that I give you the information that you need to do so.

We must remember that basil is a heat loving, full-sun herb, and that it does not like cool temperatures. If you don’t want to accidentally kill your beautiful basil plants, follow my lead and learn from my mistakes; I’ve already made them!

How to Grow Basil from Seed

To save the most money (and have the most fun, clearly!) you’re going to want to start your basil from seed. To be honest, figuring out how to grow basil from seed is incredibly easy; I always have an excellent germination rate, and I’m sure you will too!





Basil can swing wildly between 5 and 14 days for germination. I know this sounds a little bit crazy or unbelievable, but it’s true! If you want a quick germination stage with your basil (which I’m sure you do), you need to keep the seeds warm at around 70*F and slightly moistened. Plant the seeds in a rich seed starting mix or high quality potting soil, water them thoroughly, and stick them in a warm spot. If it’s spring or summer, you could put them in a sunny window sill. If it’s fall or winter (early spring, too), you would be better off using a heating pad with your seeds. If the temperature dips below 70*F, germination may be slowed. If the seeds are consistently under 70*F, you will find that germination may reach towards the slower end of the scale.

Once the tiny little basil seedlings rupture from the soil, you will see two “D” shaped leaves; you should place these seedlings in your sunniest window or under your growing lights so that they will continue to grow. After a week or so, you should see the first true set of leaves begin to unfurl. Congratulations! You’ve grown your first indoor basil seedlings!

 How to Grow Basil from Cuttings

If you already have an established, mature basil plant (or if you know someone who does), you could also start some basil plants from cuttings. Once you learn how to grow basil from cuttings, you’ll be able to expand your basil plant collection far more rapidly than you could with seedlings!




To begin, select healthy, sturdy branches that are approximately 4″ to 6″ long from the mother plant. Ensure that they are healthy, disease free, and free of heavy pest damage. Cut these sprigs at a 45* angle, remove all but the top two leaves, and dip them in rooting hormone. Be sure to cover a few leaf nodes with the hormone, as this is where the roots will form. Shake off the excess, stick the bottom third of the cutting into sterile, moistened potting soil, place a clear plastic bag around the pot and cutting, and stick it in spot outside of direct light. The clear bag will create a greenhouse effect, preventing water loss from the remaining leaves; leaving it out of direct light will allow the cutting the dedicate its energy towards root growth, rather than producing leaves or food.

Root growth should occur within 2 weeks, at which point you have a new basil plant! If you do not have rooting hormone on hand, skip on down to “growing basil in water.” You can actually root basil in water, it is a little more hands on, but it will save you the cost of rooting hormone if you don’t have it.

Growing Basil in Pots

Unless you are growing your basil hydroponically or out in the garden, you’re likely growing it in pots. Growing basil in pots is pretty straight forward; like many other potted herbs!

To start, you need adequate space for the root system. The plants will grow up to 2 feet, or 24 inches, in height. I strongly recommend a 10″ standard sized pot to allow your basil to reach its full potential, in regards to mature size and harvest.

The pot should have drainage holes and an accompanying drainage plate; this will keep the soil from becoming saturated, yet allow soil to wick up moisture if it becomes too dry. In addition, the plate will protect the surface that the pot is resting upon.




Add some high quality potting mix to the pot, and you are good to go! Do not compact the soil in the pot, as the roots require loosened soil and oxygen. Be sure to keep the soil moistened, so that the plant has water available at all times. Further down, we will dive more deeply into indoor basil care; there, you will find more information regarding managing your plants until harvest.

Growing Basil in Water

Did you know that you don’t even have to have soil in order to grow basil?! Hydroponic gardening is exciting, intriguing, and really quite successful and affordable.

You can also root basil cuttings in water, in lieu of rooting hormone. Simply remove all but 2 of the uppermost leaves from a 6″ basil cutting, and place it into some cool water in a dimly lit area. Within 2 weeks, you should see roots; the plant can then be planted into soil!

If you want to pursue hydroponic basil from seed (or cutting) to harvest, you will need a small hydroponic setup. Some people do manage to grow basil in water in a jar, on a window sill, with some added water soluble nutrients. While this can work, it will not maximize the yield that you COULD receive from the same amount of space. In a hydroponic garden, the basil will need a balanced fertilizer; you want to support foliage growth, as you are not growing fruits or flowers on these plants. In addition, they will need a consistent source of light (we will discuss this more under Plant Care below). Always keep an eye on your nutrient, water, and algae levels within the hydroponic system. A lack of proper nutrients or water will stunt or harm production, while algae can clog filtration systems and steal nutrients.

If you choose a basic, primitive hydroponic system, you could get away with a plastic tote, some nutrients and trace minerals, water, and a basic lighting setup. There are more complicated systems that involve air or water pumps, but we will save that for another post.

Basil Plant Care Indoor

Basil, like many other herb plants, needs relatively basic care indoors. For the most part, you will not need to provide anything special or out of the ordinary for them to thrive. As the seeds sprout, you can place a fan on them to keep air moving throughout the seedlings, reduce the risk of fungal infection, and to strengthen the stems of the seedlings as they grow.

  • Water Requirements of Basil: Water your basil when the soil becomes dry. Never leave basil with “wet feet”, as this invites problems with fungal and bacterial infections, as well as root rot.
  • Light Requirements of Basil: Basil needs 8 hours or more of light per day. When using artificial lighting for plants, try to use an automatic timer; otherwise, fluctuating daylight hours could trigger early flowering.
  • Pruning Requirements of Basil: Basil should be topped regularly (every 2 weeks, or as needed) to encourage bushy growth. Flower buds should be pinched or pruned the moment that they appear.

  • Temperature Requirements of Basil: Basil loves hot weather, and does not do well when temperatures regularly dip below 45*F. This will stunt growth; regular temperatures under 40*F generally trigger damage.

  • Feeding Requirements of Basil: Offer the plants a balanced fertilizer once every month, unless the plants show signs of deficiencies. If you are using rich compost, worm castings, or pre-fertilized potting mix, do not fertilize the seeds at sowing or at emergence; instead, give the plant approximately 30 to 45 days before feeding.

Indoor Pruning

Pruning basil is an excellent way to encourage a basil plant to stand sturdy and produce heavily. As the young plant grows, you’ll want to “top” it every 1 to 2 weeks, depending on how much basil you would like to produce. Please keep in mind that the larger, bushier, and healthier a plant is, the more water and nutrients it will require.

Every time that you “top” the basil, you’ll simply be snipping off the top of the the central stalk. Some plants may require topping of their secondary branches as well; it all depends on how lanky and tall the plant is. Every time that you cut the top off, the basil plant will grow new branches at an angle, away from the center stalk. This results in a shorter, stockier basil bush that takes advantage of horizontal space, rather than vertical. It also encourages the plant to produce far more leaves, which is exactly what you are interested in harvesting.

Basil Plant Flowering

Unless you are trying to harvest basil seeds, you do not want your basil to go to flower (or produce seeds!). If you would like to produce just enough seed to save, you could allow one plant to flower while pruning the rest.

If you see buds forming, pinch them off immediately. They will hinder leaf production. This directly works in your favor, but all will be just fine as long as you remove the buds from each plant as they begin to develop.

Most gardeners will find a basil plant flowering when the days are at their longest, and the temperatures are at their warmest; many plants are triggered to reproduce by the lengthening daylight hours or the shortened daylight hours after the longest day. When using indoor gardening lights, this process can be kept at bay longer with a reliable timer. A grow light timer turns the lights on and off at the same time every day.

Harvesting Basil Seeds

If you are trying to attempt harvesting basil seeds for the first time, you’re probably going to be very excited to see your first flowers!

As these flowers appear, ensure that you offer the plant any needed fertilizer feedings. As long as the plant is well fed, receives plenty of light, and stays moist, it should produce a lot of healthy seeds for you.

Once the flowers begin to fade and the seed pods have started to develop, watch the pods for signs of maturity. Pods will dry out and become brown. Once this occurs, test a pod by breaking it open. You should find mature, dark, and hardened basil seeds within the pods; they should also be removed easily.

The mature seeds can then be harvested and cleaned, removing as much plant debris and dirt as possible. Place the seeds into a resealable, small plastic bag, and store them in a dark, cool place. You may store the seeds in the freezer, too. This will simulate a winter, increasing the germination rate among basil seeds. Freezing seeds also helps them to store longer!

Ideal Rotation Schedule: How to Grow Basil Indoors Year Round

If you want to grow basil intensively year-round, you will need to master a gardening schedule. Firstly, it is important to know that basil will require 60+ days before reaching an optimum harvest size. This allows you to grow 4 to 6 batches indoors per year, if you are using all of your available growing space at one time. For the highest yields, start seedlings in another area of the home 2 to 3 weeks before the current crop is to be harvested; this way, the seedlings have a head start as soon as the previous plants are harvested. Continue this process without interruption for a steady supply of this aromatic herb. You must keep plenty of extra light bulbs on hand in this scenario, as you do not want to leave your basil plants without light for up to a week until an order arrives at your door.

Knowing how to grow basil indoors year round is only part of the battle; you must also be diligent in disease control. Protect your plants from disease, or you may face catastrophe. Damping off can destroy an entire batch of seedlings, while verticillium wilt can destroy an entire, healthy, large crop with little notice. The risk of disease is magnified with each new batch of seedlings in used potting soil and pots.

Always clean pots with bleach in between batches. Bleach will kill off any pathogens, parasites, or fungal spores that might be lingering within the microscopic scratches in the pot’s surface. The soil should be cleaned, or replaced, with each batch, too. The easiest way around this is to simply replace the soil. However, this isn’t very cost effective if you’re a frugal individual. Sterilizing the potting soil properly, through an oven or a microwave, isn’t a very hard process. The downfall is that it might stink up your home for a little while.

Growing Basil Indoors In Winter

Two of the biggest obstacles that people face when growing basil indoors in winter are low temperatures and reduced daylight hours. These two problems could easily be solved, as long as you are growing the basil in a controlled environment (it’s unlikely that your garage or basement would qualify).

To avoid swings in temperature, grow the basil plants in a room on the southern side of the home, and do not place the basil plants against a window. Windows may be great for absorbing sunlight, but at night, leaves could be exposed to temperatures under 50*F which may stunt or harm the plant. Temperatures under 40*F will likely cause irreversible cold damage or death to basil, as it does not like cool temperatures. Use a heated seedling mat or a reptile heat mat beneath freshly sown seeds to keep germination rates in an acceptable range, and ensure that the room that the basil is being grown in is sufficiently heated at night time.

You should not rely on the available winter sunlight for growing basil. While you could take advantage of it on a sunny day, you will still need supplemental lights in order to keep basil growing at a decent rate over the course of the 2 months. Offer at least 8 hours of light for the best results.