Basil is a staple in many herb gardens, mainly because it can be easy to grow, but it’s also quick to tell you when something is not quite right. Like, when you see your basil plant wilting, that’s a sure sign that it needs something.
That something could be as simple as a little water that needs to be added to the soil, or it might be something more serious.
What Basil Plants Need to Prevent Wilting
1 – Careful Soil Selection
The soil formulation you use to grow basil will affect the quality of the produce, and it can go a long way at preventing your basil plant from wilting. That’s because basil plants prefer a slightly acidic potting mix in the range of 6.0 to 6.5.
As a rough guide to the pH balance of soils, closer to a pH 7 is better for flowering plants, and less acidic soils under pH 7 is better suited to foliage plants.
Basil can produce flowers, but the energy it spends on flowering, detracts from the energy needed to stop the leaves from wilting. So, ideally, anything you can do (including pruning) to stop the plant from flowering, will also prevent a basil plant wilting.
For that reason, the soil pH should be below a 6.5 pH, and you can go as low as 5.5 pH. A good way to increase the acidity of soil is to increase the amount of organic matter used in the potting mix.
The other thing you need to make sure you have is good drainage. Basil prefers the soil to be constantly moist but never soggy. For that, some perlite or vermiculite should be used to improve the drainage.
2 – Maintain the Ideal Temperatures
Basil plants do best in a very specific temperature range. 80oF (27oC) to 90oF (32oC). Below that is too cold and it’s more likely to result in leaf damage than leaf droop.
On hot days, when you see a basil plant wilting, it’s an indication of extreme heat. The hotter the climate, the faster the soil dries up. It’s not that the plant drinks more in hot weather, it’s just that the water evaporates quicker.
Adding more water on hot days can see a wilting basil plant perk up within hours, but you should also shelter it from direct sunlight to prevent the water evaporating as fast in extreme heat.
An inch of water a week is really all a basil plant needs. If you have to give it more than that, it’s probably exposed to temperatures too high for it to thrive.
Full sun is advised, but around midday, when the sun is strongest, basil plants may need a little shade.
3 – Flowerheads Removed Before They Bloom
Pruning effects how basil tastes, but beyond enriching the flavor, it’s also something that prevents basil plants from wilting. For best results, it’s ideal to trim the plant back frequently.
During growing season, these usually grow abundantly so any wilting leaves you do see, can be snipped off the plant. A little wilting is normal, just not on the entire plant.
If you’re seeing every branch with limp leaves, it’s likely either a watering problem or a temperature problem.
In cases when it’s only a few leaves, prune away the unhealthy ones first. Another point of note is the flowers that bloom from basil. When basil is focusing energy on blooming flowers, it’s diverted away from the foliage so you can prevent some wilting by pruning away the flowerheads when they appear and before they bloom.
4 – Harvest More Often
You shouldn’t wait to prune the leaves on a basil plant until you need them. You need to harvest them as often as possible, which means taking more than what you need for a recipe.
The more you cut the plant back, the more foliage it will produce. The longer you leave it, the higher the likelihood that older leaves will become droopy.
During the growing season, you can expect to get a full harvest every few weeks. Cut it back from the top by up to a third of the plant’s height, making the cut as closely above a leaf pair as you can so as not to leave a snub on the stem.
As a rough guide, consider snipping back each branch every time it produces six to eight leaves. That should be roughly every few weeks during the growing season.
5 – Steps Taken to Prevent Basil Diseases
If you’re growing basil from an already established plant, it may be something more sinister that’s wrong with your plant. Two diseases that’s been affecting sweet basil plant varieties for years are “downy mildew” and “fusarium wilt”.
Wilting is par for the course with either of these diseases, but it’ll be short-lived, because the plant can rarely fully recover. The best way to grow basil is from seed so you can control the quality, ensuring it’s free from disease before you put it into your herb garden.
To date, the Amazel Basil® seed is among the most resistant to downy mildew. Most others are highly susceptible to this disease.
A better quality is that it is a seed sterile variety, so closer to the end of the growing season, it won’t be focusing energy on seed production, but instead, it continues to produce vibrant leaves and shoots, giving it a longer life cycle too.
The biggest threat to all varieties of basil is blight. Leafspot usually happens because of a lack of airflow and that’s usually a problem when the plant is overcrowded.
The closer you have containers growing together, the less air movement there is. A lack of airflow sets the stage for leaf blight to take hold and once that happens, the leaves will start wilting, then yellow, eventually turning brown or black, fall off and die.
Insect control for Basil Plants
Important to remember is that basil is delicious and nutritious for humans and insects. Given the chance, pests will feed on your plants, and if you don’t act fast, they can quickly lay eggs in the soil, multiplying so fast that within days, you could have an infestation on your hands.
Some of the most common insects attracted to basil are:
- Spider mites
- Japanese Beetle
The larger insects you’ll be able to see and remove with your hands, but the smaller ones, those are the most evasive that call for smarter actions.
Aphids and whiteflies are attracted most to the basil plant because the leaves are extremely tender making it easy for these tiny insects to suck what little juice that’s inside the leaves right out of it. That will leave your basil plants wilting.
A good amount of air circulation helps to prevent infestations, but even when your plants are well-spaced, infestations can happen.
Both insects are similar in size, but they look different. Aphids are translucent so they’re more difficult to see, but whiteflies, being white, you’ll spot them easily, but only once there’s a lot of them.
Neem oil, or insecticidal soap are both effective ways to get rid of aphids and whiteflies on indoor basil plants. These are a contact poison for a number of soft-bodied insects including spider mites, which can also be problematic on basil plants.
For garden plants, a more effective solution for aphids is to order a batch of ladybugs, either online or from your local nursery as these can be set loose around your garden soil.
Ladybugs are good bugs and will feed on aphids. Once they’re done, they won’t stick around one zone in your garden.
If you have aphids elsewhere, they’ll hunt them out and eat them, then when they’re running out of food, they’ll head off in search of more, such as your neighbor’s garden, helping to keep the insect population down in and around your garden space.
Two other larger insects that tend to be attracted to basil grown outdoors are slugs and the Japanese Beetle. Slugs feed at night and a sign of these damaging your garden is the trail of slime they leave in their wake.
If you have a snug or a snail problem, you’ll notice holes in the lower leaves of your plant and the silvery trail. You can either hunt for them in the night by torchlight to remove them by hand, or the simpler solution is to use any of these tips to get rid of slugs and prevent them coming near your plants in the future.
Japanese Beetles also leave holes in the foliage of basil plants and they tend to be early morning feeders. The difference is where they feed on the plant.
You’re more likely to see holes in the upper part of the plant when there’s Japanese Beetles present. These are big enough to be see and remove by hand, but you can also spray them with insecticidal soap or neem oil too.
If you have Japanese Beetles present, it’s likely you’ll need to treat the soil because these insects lay eggs in the soil, which then hatch into a white grub, which start feeding on the top inch of the soil before maturing the adult Japanese Beetle.