A basil plant that is healthy has bright green stems that hold up its lush leaves. Over time, though, you may notice that the stem near the soil line and on the older, lower parts of the plant turn brown. This discoloration moves up the main stem slowly and can turn black in the worst cases.
Brown basil stems are usually a cause for concern since they signal underlying issues with your plant’s health. In this article, we’ll explore the various reasons for basil stem browning and what you can do to treat and prevent it.
Why Do Basil Stems Turn Brown?
There are 4 main causes for basil stems turning brown
1. Natural Maturity
As an annual herb, basil goes through its entire lifecycle in one growing season. Towards the end of this cycle, you’ll notice flowers and flower buds forming on the plant as it tries to produce seeds before dying off.
The plant stops putting its energy into growing leaves once it starts flowering and making seeds. Little by little, the leaves get smaller, and the stems turn brown and woody. This browning is a normal part of basil going bad and doesn’t need to be fixed.
2. Root Rot
Root rot disease can happen when there is too much water around the roots because of too much watering or poor drainage. This mold infection starts at the stem’s base and works its way up to the roots, turning the stem brown or black.
Above ground, you’ll notice wilting, yellowing leaves, and stunted growth along with the discolored stems. Root rot can quickly kill basil if left unchecked.
3. Fungal Infection
Basil can get a number of fungal diseases, such as fusarium wilt, verticillium wilt, and phytophthora blight. The best conditions for these fungi to grow are high humidity and poor air flow.
Though symptoms vary based on the type of fungus, brown/black basal stems are common. The leaves also turn yellow or brown and drop off eventually. These fungal infections spread rapidly, infecting the whole plant.
4. Cold Weather
Basil is a warm season herb that does poorly in temperatures below 50°F. Exposure to frost or chilling winds can shock the plant, causing its stem and leaves to blacken and die back.
Bringing potted basils indoors in cold weather prevents this type of damage. The browning only affects the exposed parts of the stem rather than being systemic.
What To Do For Brown Basil Stems
Once you identify the cause behind the browning stems, take appropriate corrective measures:
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Maturing plant – Prune flowers/buds to prolong leaf production. Harvest remaining leaves and seeds at end of season.
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Root rot – Improve drainage; water correctly. Remove badly infected plants to prevent spreading.
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Fungal infection – Isolate and discard infected plants. Improve air circulation. Treat with fungicides.
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Cold weather – Move potted plants indoors in winter. Cover outdoor plants with row cover/cloche.
Along with these fixes, fertilizing with a balanced soluble fertilizer like 10-10-10 or fish emulsion provides nutrients to support recovery. Trim off any severely damaged parts of the stem to improve appearance and air circulation.
How To Prevent Basil Stem Browning
With proper care and culture, you can avoid many of the causes behind basil stems turning brown:
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Grow basil in well-draining soil and avoid overwatering that leads to soggy soil. Water only when the top inch becomes dry.
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Make sure indoor and outdoor plants get 6+ hours of sunlight daily. Insufficient light causes weak, stressed growth.
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Pinch off flower buds frequently to prolong the leaf production stage. Allow flowering only if collecting seeds.
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Space basil plants adequately to allow air to circulate freely around them. Closer spacing increases humidity.
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Check plants daily for signs of pests like aphids. Pest infestations introduce diseases that cause browning.
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Add 2-3″ of mulch around outdoor basil plants. This insulates roots and prevents frost damage.
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Bring container basils indoors or transplant to a greenhouse once night temperatures drop below 50°F.
Common Questions About Basil With Brown Stems
Here are answers to some frequently asked questions about dealing with basil plants that have brown stems:
Can I still use basil leaves if the stems are browning?
Yes, unaffected leaves from a basil plant with browning stems can be used for culinary purposes. Trim off and discard any leaves that show signs of browning or wilting before harvesting the healthy leaves.
Should I prune the brown parts of a basil stem?
It’s generally recommended to prune off the brown and blackened parts of the basil stem to improve air circulation and appearance. Make the cut an inch or two below the discolored portion to remove it entirely.
How do I revive a basil plant with brown stems?
Moving the plant to a sunny spot, pruning away dead parts, and resuming proper watering may help it recover. Fertilizing also provides a nutritional boost. But if the cause is fungal disease, infected plants typically can’t be revived and must be discarded.
Why are my basil stems turning black?
A blackening stem indicates advanced stages of fungal infections like fusarium wilt. It also can happen from bacterial diseases or extreme cold weather damage. To prevent spread, remove and destroy blackened basil plants.
Should I pull up basil plants with brown stems?
If the browning is limited to just the lower stem and the rest of the plant looks healthy, it may recover and not need removing. But any stems that are turning black should be pulled up along with badly infected or dying basil plants to prevent disease spread.
Conclusion
Although brown basil stems may look unsightly, they don’t necessarily mean a total loss of your plant. By identifying the underlying issue and taking appropriate corrective care, you can often revive the plant and bring it back to full vigor.
But some causes like fungal infections require removing and destroying affected plants to protect the remaining healthy ones in your garden. Catching basil problems early maximizes your chances of saving the plant.
With preventative care measures and prompt troubleshooting, you can continue enjoying abundant harvests from your basil for months to come!
How to Avoid Basil with Woody Stems
Basil, Ocimum basilicum, is a member of the Lamiaceae or mint family. Basil is grown primarily for its tender, young leaves which are used either fresh or dried in Asian and European foods. Proper planting and ongoing care of basil give it the best chance to flourish and avoid disease and pests. Basil, like most herbs, likes lot of sunshine, at least six to eight hours per day. Propagation by seed is simple. You can direct sow into the garden after all danger of frost has passed or start seeds early indoors (six to eight weeks prior to planting outside). Sow the seeds evenly and cover them with ¼-inch (. 6 cm. ) of well-drained soil with a pH of 6. 0-7. 5. Within five to seven days, youll see the seedlings begin to emerge. Keep the seedlings moist but not drenched or they may develop a fungal disease called damping-off. To thin or move the seedlings, wait until they have two or three sets of leaves and then do so. ) apart. Mulch around the plants with grass clippings, straw, compost or ground leaves to help retain moisture and retard weeds. Water the basil every seven to 10 days, depending upon rainfall. If the plants are in containers, they may need additional water. Lightly fertilize basil with a 5-10-5 food once or twice at the rate of 3 ounces (85 g) for every 10 feet (3 m. ) of planting space. If you grow basil inside, use liquid fertilizer that is half as strong as the package says to every four to six weeks. If you grow basil outside in pots, use it every three to four weeks. Follow all of the above and you should have an abundance of lovely, aromatic basil leaves to harvest. But what happens if you start getting woody basil plants?.
Troubleshooting Woody Stems in Basil
Basil, unlike some plants, actually loves to have a little taken off the top. You can harvest as soon as the plant is a few inches tall. Snip young leaves or, if you are harvesting an entire stem, cut above a pair of leaves. This encourages new growth at the cut which should be visible within a week. Keep trimming the basil throughout the growing season to encourage growth. Strain the basil and hang the stems to dry. You can also freeze the basil in ice cube trays and use it later. Puree the basil with either a little water or olive oil, put the puree in the tray, freeze, and then pop them out and store the cubes in the freezer in an airtight container for later use. The important thing is to keep pruning your basil. If you don’t, the plant will flower and make seeds, which will turn the stems woody. The leaves will turn bitter as well. If youre growing the basil as an ornamental for its attractive foliage and flowers, then you probably don’t care if the basil stems are turning into wood. If, however, you love those succulent young leaves, keep snipping. Not cutting back old stems makes them woody, just like letting a plant flower does. Do keep in mind that basil is an annual. Bringing the plant inside when it gets cold will make it last a little longer, but it will die in the end. Woody basil plants simply mean that the plant is protecting itself from the dipping temps. If you bring it inside, give it plenty of light. Production will slow in the winter, but you should still be able to harvest some delectable fresh basil leaves to enliven your winter meals.