Gardening Plants & Flowers Herbs

How Often to Water Basil

Water needs for your favorite herb

watering potted basil

The Spruce / Lacey Johnson

Growing basil (Ocimum basilicum) is not difficult, as long as you know how to water it. The schedule may vary depending on your climate and whether you have it planted indoors or outside. Generally, this perennial herb does well in warm climates and thrives in full sun. However, it still likes moist, well-drained soil.

"Just like an outdoor garden, every indoor growing space is unique," says Jordan Mara, founder of Mind & Soil. "Rather than having a strict watering schedule, focus on paying more attention to the foliage and soil to determine whether the plant is in need of its next watering."

Here is everything you need to know about basil watering needs.

Meet the Expert

When to Water Basil

Terracotta pots with basil

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Basil loves moist soil, so it makes sense to give the herb infrequent deep waterings instead of daily shallow watering. The reason for this approach? You want the water to penetrate at least 2 inches of soil so it won't dry out as quickly through evaporation.

"Additionally, this trains the roots of the plant to search down more deeply for water, creating a larger root system," Mara says.

A mature plant will likely need a good deep watering once a week, but of course this might depend on the environment, especially if the basil is planted inside.

"This is because the light source is not as intense as the sun and there is generally less airflow indoors," Mara says. "As a result of a less intense light source and less wind, the soil will not dry up as quickly."

For outdoor basil gardens, Mara says the best time of day to water basil  that grows outside is either first thing in the morning or in evening.

"Avoid watering in the middle of the day as the water will evaporate most quickly at this time and water on the leaves can result in burning from the sun," he says.

Basil Water Schedule: Indoors and Outdoors

Like with most plants, the frequency of watering depends on the amount of light, temperature, humidity, soil type, and potting container. The main thing to keep in mind when it comes to basil is that it likes moisture.

As a rule of thumb, you want to aim to water once a week, however, if your basil is potted indoors, you may want to increase watering to every two to four days as the water may evaporate quicker.

This approach also applies to basil in pots, even if it is outside. Unlike basil that grows in the ground, potted basil can dry out faster.

"This is because rather than only the top of the soil being dried out by sun and wind, now all sides of the pot are being exposed to the sun and wind," Mara explains. "As such, evaporation now occurs from all directions."

However, it's important to keep in mind that every environment is going to be different. Brown recommends focusing on paying attention to the actual foliage of your plant and digging down two inches into the soil rather than a fixed schedule.

Light

Basil loves sunlight. It grows exceptionally well when exposed to about six to eight hours of light each day. Keep in mind that even though this herb loves the sunshine, if you have direct midday sun, it may dry it out too quickly.

Ideally, basil should have full morning sun that isn't too intense. If you notice that the leaves are pale green, instead of vibrant green, that means the herb may not be getting enough light. If your potted basil is indoors, move it to a sunnier location.

Temperature and Humidity

Very warm temperatures are quite hospitable to basil. You will have a full plant when the temperatures range between 80 and 90 degrees Fahrenheit. If the temperature goes above 95 degrees Fahrenheit, the plant may undergo stress and the leaves may dry out. In that case, increase the watering frequency and create artificial shade.

If the temperature drops to around 50 degrees Fahrenheit, the basil will not do well and the leaves may blacken. Anything below 45 degrees Fahrenheit is likely to harm your herb.

When it comes to humidity, basil will thrive when the levels are somewhere between 40 and 60 percent. Indoor humidity is typically around 30 and 60 percent, so your window sill planters of herbs should do just fine.

Soil Type

Basil does well in well-draining soil. You can purchase vegetable and herb potting mix for both your planters and garden beds. If you have your soil tested for pH levels, basil will grow well in the 6.0 to 7.5 range.

Potting Container

Basil loves well-draining soil, so make sure that if you are using a planter, it has well-draining holes. You do not want the basil roots to sit in water. Also, make sure that your potting container has ample space for roots, a large pot that is at least 9 inches deep and 12 inches wide is a good start.

Basil does especially well in raised beds or containers because both offer drainage and a welcoming environment that retains heat. This is particularly helpful in the spring when the plant is establishing.

How Basil Plants Hold Water

Basil is a humidity-loving plant and can absorb moisture through its leaves. This means you can mist the herb, in addition to providing it with plenty of water. The plant uses its roots to drink up water, but too much water around the roots can cause them to rot.

For deep watering, Mara suggests the following: use a watering can or the shower setting on your hose and begin watering the soil all around where the stem enters the ground. If possible, avoid watering the leaves and only water the foliage.

Once the water begins to pool, move on to your other plants and return to the basil plant after two to three minutes. Dig down 2 inches again to check and see if it's moist. If it is, you're all finished. However, if it is not moist 2 inches down, do a second round of watering. Repeat this process until the soil is moist 2 inches below the surface.

Gardener watering basil out of a watering can

Nadya So / Getty Images

Signs Your Basil Plant Is Underwatered

Sad, sagging leaves are a sign that basil needs more water. If the plant is wilting, find a watering can pronto. You should also look at the soil level, if it is dry at the two inches level, it is time to water, Mara recommends. Here is what you should look for.

  1. Wilting leaves
  2. Sagging and drooping stems
  3. Dry soil at the base of the plant

Remember, basil needs at least 1 inch of water every week to stay healthy and thrive.

Signs Your Basil Plant Is Overwatered

According to Mara, if your basil plant's leaves start to show brown or black spots, it is a sign that you are overwatering. Keep an eye out for the following.

  1. Brown spots
  2. Wilting stems
  3. Yellow leaves at the base of the plant
  4. Foul soil smell (a sign of root rot)

Note that brown spots on leaves could also mean that the environment is too cold for the basil. (You'll also see this happen in the fridge if the temperature is too low). Store herbs in a crisper or in the front of the fridge if this is the case.