Boric acid is a naturally occurring compound that has long been used in a variety of applications, including as an insecticide, preservative, and antifungal treatment. More recently, boric acid has gained popularity among gardeners and indoor plant enthusiasts as a supplement to add to soil. But is boric acid safe to use on plants? And what benefits might it provide? Let’s take a closer look at how boric acid works and how it can be used in gardens and with houseplants.
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What is boric acid?
Boric acid, also known as hydrogen borate, is a weak acid that is formed from the reaction of borax (sodium borate) with a mineral acid. Its chemical formula is B(OH)3. In nature, boric acid exists due to the breakdown of boron-containing minerals and compounds by plants, animals, water, and changes in pH.
Boric acid powder is white and crystalline in structure. When dissolved in water, boric acid forms borate ions which are the active compound. Borate ions have antifungal, antibacterial, and insecticidal effects. Boric acid and borates have low toxicity to humans and plants, making them useful compounds for pest control.
Some key facts about boric acid:
– Naturally occurring compound, mined from boron-containing minerals
– Low toxicity to humans and plants
– Antibacterial, antifungal, and insecticidal properties
– Commonly used as an insecticide, herbicide, and wood preservative
– Available in powdered form for agricultural use
Benefits of boric acid for plants
When applied to soil, boric acid can provide a number of benefits for plants:
Insect and pest control
Boric acid is highly toxic to insects and other arthropods, including ants, cockroaches, silverfish, and termites. When insects ingest or come into contact with boric acid, it causes irritation of their digestive system, leading to dehydration and eventual death. The insecticidal properties of boric acid make it useful for controlling common garden pests.
Prevention of fungal diseases
The borate ions derived from boric acid have antifungal abilities. Fungal diseases like root rot, stem rot, and blights can be destructive in gardens. Applying boric acid to soil creates an environment that is inhospitable for fungal growth. The compound prevents spores from germinating, protecting plants from fungal diseases.
Increased boron levels
Boron is an essential micronutrient that supports plant growth and development. It aids in cell wall formation, lignification, carbohydrate transport, and nurturing root growth. Many soils are deficient in boron naturally. Adding boric acid can supplement boron levels to optimize plant health.
Nutrient availability
There is some evidence that boric acid makes key nutrients like nitrogen, phosphorus, and potassium more plant-available when applied as a soil amendment. The mechanism is not fully understood, but the borate ions may facilitate ion exchange and chelation in the soil. This improved nutrient uptake results in benefits like stronger stems, increased bloom set, and more robust growth.
Is boric acid safe for plants?
When used properly, boric acid is a safe supplement for plants. Here are some key factors regarding its safety:
– Low toxicity – Boric acid has a low toxicity for both humans and plants. It takes high levels of exposure to cause negative effects.
– Selective toxicity – At recommended application rates, boric acid is more toxic to insects than mammals or plants. This makes it safe for use around gardens and houseplants.
– Non-residual – Boric acid breaks down naturally in the soil and does not persist or accumulate to toxic levels. It does not lead to soil contamination issues.
– Low leaching – Boric acid stays where it is applied and does not readily leach or travel through the soil. This prevents groundwater contamination.
While boric acid is safe at low concentrations, over-application can potentially cause plant damage. Always follow label directions for proper dosing.
How to apply boric acid to plant soil
If you want to use boric acid as an amendment for your garden or houseplants, here are some application guidelines:
Get the right form
Look for boric acid in powdered form. This allows for thorough incorporation in the soil. Avoid gel baits which are not designed for soil applications.
Dosage
The recommended dosage is 1/2 teaspoon of powdered boric acid per 1 gallon of soil. Exceeding 1 teaspoon per gallon can potentially cause plant injury.
Incorporate evenly
Thoroughly mix the boric acid powder into the soil before planting. This enables even distribution and prevents concentrated pockets.
Apply annually
Boric acid breaks down over time and leaches out with watering. Re-apply at the start of each growing season for ongoing benefits.
Don’t overdo it
More is not better when it comes to boric acid. Excess amounts can build up and become toxic. Carefully measure and follow dosage guidelines.
With the right application, boric acid can be a helpful supplement for gardens, houseplants, and agricultural crops. Always read and follow label instructions to use this tool safely and effectively.
What plants benefit from boric acid?
Boric acid can benefit a wide variety of vegetables, fruits, flowers, trees, and indoor plants. Here are some examples of plants that may see improved health with boric acid soil applications:
Vegetable garden plants
- Tomatoes
- Peppers
- Potatoes
- Carrots
- Cucumbers
- Melons
- Squash
- Cabbage
- Broccoli
- Green beans
These vegetable crops are prone to fungal issues and insect pests. Boric acid can help control diseases like early blight, powdery mildew, and root rot. It also deters pests like aphids, spider mites, and beetles. The boron supports healthy plant development for higher yields.
Fruit trees and berries
- Apples
- Cherries
- Peaches
- Pears
- Plums
- Citrus
- Strawberries
- Blueberries
- Raspberries
Boric acid aids fruit production in trees and berries. The boron enhances flower pollination and fruit set. It wards off fungal diseases like peach leaf curl, brown rot, and blossom blight. Boric acid also controls damaging pests like aphids, borers, and Japanese beetles.
Ornamental flowers
- Roses
- Petunias
- Marigolds
- Zinnias
- Chrysanthemums
- Dahlias
- Iris
- Lilies
Flowers prone to mildews and fungal issues benefit from boric acid’s antifungal activity. It also provides pest control against aphids, thrips, and fungi gnats. The boron improves bud formation and flowering. Use boric acid to boost floral displays in garden beds and containers.
Trees and shrubs
- Evergreens
- Spruce
- Pine
- Juniper
- Arborvitae
- Dogwood
- Crepe myrtle
- Lilac
Boric acid supplements boron for structural strength and health in ornamental trees and shrubs. It deters fungal needle diseases and improves resistance to environmental stress. Scale insects, borers, and leaf miners are also controlled with soil drenches.
Houseplants
- Orchids
- Peace lily
- Dracaena
- Ficus
- Ferns
- Palms
- Succulents
- Bromeliads
Indoor plants benefit from boric acid through fungal disease prevention, increased boron nutrition, and control of common pests like fungus gnats, mealybugs, and spider mites. It is especially useful for sensitive orchids and bromeliads.
Alternatives to boric acid for plants
If you prefer not to use boric acid on your plants, there are some alternative options:
Insecticidal soaps
Insecticidal soaps derived from potassium salts of fatty acids can control soft-bodied insects like aphids, mealybugs, and mites. They have low toxicity to mammals and plants.
Neem oil
Extracts from the neem tree have triterpenoids that disrupt insect life cycles. Neem oil can combat leaf miners, caterpillars, beetles, and other pests when sprayed on plants.
Diatomaceous earth
Diatomaceous earth is comprised of siliceous skeletal fragments of marine phytoplankton. The sharp edges physically damage small insects. It is low risk for plants when dusted on foliage or applied to soil.
Beneficial insects
Releasing predator insects like ladybugs, lacewings, and parasitoid wasps allows natural pest control without chemicals. They feed on problem insects.
Fungal supplements
Adding organic fungal amendments like mycorrhizae and trichoderma to soil can prevent fungal diseases through competition and antibiosis. They strengthen plant immune systems.
Always evaluate alternatives carefully to ensure they provide the pest control and disease prevention benefits needed for your garden. Integrated pest management using multiple strategies is often most effective.
Risks and precautions for boric acid use
While boric acid is generally safe when label directions are followed, there are some important precautions:
– Keep away from pets and wildlife. Boric acid can be toxic if directly ingested. Take care to avoid exposure to non-target animals.
– Avoid contact with plants. Direct contact with leaves and stems can potentially cause burn. Target just the soil.
– Wear gloves and wash hands after use. Protect skin and avoid accidental ingestion while applying.
– Do not use near food crops within 1-2 weeks of harvest. This prevents any chance of residual traces on edible produce.
– Avoid getting in lakes, ponds, or streams. High concentrations of boron can be toxic for aquatic life.
By using care with application and following label rates, risks are low. But it’s wise to handle boric acid cautiously and keep it away from children and animals.
Frequently asked questions
Does boric acid change the pH of soil?
No, boric acid is a weak acid that has minimal influence on soil pH. It helps control fungi and insects but does not significantly alter soil acidity or alkalinity.
How long does boric acid last in soil?
Boric acid degrades over time, so it must be reapplied every 3-6 months. It gradually breaks down through leaching and chemical processes. Rainfall and watering will wash some of the active compound away.
Can you use boric acid in organic gardening?
Yes, boric acid is allowed under USDA organic standards in crop production. Always verify a product’s organic certification before using in an organic system.
Does boric acid kill beneficial soil microbes?
In typical application rates, boric acid has minimal impact on helpful microorganisms like mycorrhizal fungi or nitrogen-fixing bacteria. It primarily targets fungal pathogens and insects.
Can boric acid burn plant roots if over-applied?
Yes, excessive amounts of boric acid could potentially burn and damage plant roots and stems. Always measure carefully and follow label dosage guidelines to prevent phytotoxicity issues. Moderation is key.
Conclusion
Boric acid is a useful addition to soil for gardens and houseplants when applied properly. The borate component provides benefits like fungal disease prevention, increased boron nutrition, and insect/pest control through contact toxicity. Most vegetables, fruits, flowers, trees, and ornamental plants can gain advantages from boric acid supplementation.
While low risk, some reasonable precautions should be taken to avoid misuse. Carefully follow label directions on concentration and dosage. Measuring accurately prevents the chance of over-application. With judicious use, boric acid can be a helpful tool for plant health. Consider incorporating this multifaceted soil amendment into your horticultural program.