Can You Add Lime After Planting? Understanding Post-Planting Soil Amendment
Yes, you can add lime after planting, although it is not always the most efficient method. While it can improve soil pH over time, care should be taken to avoid damaging existing plants and to ensure proper distribution for optimal results.
The Importance of Soil pH
Soil pH plays a critical role in nutrient availability for plants. Most plants thrive in a slightly acidic to neutral soil pH (around 6.0 to 7.0). When soil is too acidic (below 6.0), certain essential nutrients, such as phosphorus, calcium, and magnesium, become less available to plants. This can lead to stunted growth, nutrient deficiencies, and overall poor plant health. Adding lime, which is essentially calcium carbonate or dolomitic lime (containing magnesium as well), helps to raise the soil pH, making these nutrients more accessible.
Benefits of Liming After Planting
While incorporating lime into the soil before planting is generally preferred, there are situations where post-planting application is necessary or beneficial:
- Unexpected Soil Acidity: Soil tests taken after planting reveal unexpectedly low pH levels.
- Established Gardens: Adjusting the pH of established gardens without disturbing existing plants.
- Topdressing: Slowly correcting acidity in lawns and groundcovers through surface application.
How to Apply Lime Around Existing Plants
Applying lime after planting requires a careful approach to avoid damaging plants and maximizing its effectiveness:
- Soil Testing: Conduct a soil test to determine the current pH and the recommended lime application rate. This is crucial to avoid over-liming.
- Choose the Right Lime: Choose either pulverized lime or pelleted lime. Pelleted lime is easier to spread evenly and less dusty, while pulverized lime reacts faster.
- Spread Evenly: Carefully spread the lime around the base of plants, avoiding direct contact with stems and leaves. A spreader is highly recommended for larger areas.
- Water Thoroughly: Water the limed area thoroughly to help the lime dissolve and penetrate the soil. This also helps to wash any lime residue off plant foliage.
- Avoid Over-Application: It is better to apply lime in smaller increments over time rather than applying a large amount all at once. Monitor soil pH with periodic testing.
Common Mistakes to Avoid
- Over-Liming: Applying too much lime can raise the pH too high, making other nutrients unavailable. Always follow soil test recommendations.
- Contact with Foliage: Lime dust can burn plant leaves. Water plants thoroughly after application to remove residue.
- Ignoring Soil Test Recommendations: Applying lime without knowing the soil pH can lead to imbalances and problems.
- Applying to Acid-Loving Plants: Plants like blueberries, azaleas, and rhododendrons prefer acidic soil. Liming around these plants will harm them.
Types of Lime
There are different types of lime available, each with its own advantages and disadvantages:
| Type of Lime | Composition | Reactivity | Application Ease | Best Use |
|---|---|---|---|---|
| Pulverized Lime | Finely ground calcium carbonate (sometimes with Mg) | Fast | Dusty, Difficult | Quick pH adjustment; requires careful handling |
| Pelleted Lime | Lime dust formed into pellets | Slower | Easy | Even spreading; less dusty; good for lawns and gardens |
| Hydrated Lime | Calcium hydroxide | Very Fast | Caustic | Very quick pH adjustment; use with extreme caution; not recommended for general use |
| Dolomitic Lime | Calcium and Magnesium Carbonate | Medium | Moderate | Correcting magnesium deficiencies along with raising pH |
Understanding Your Soil Type
The amount of lime needed to change the pH depends on the soil type. Sandy soils require less lime than clay soils to achieve the same pH change because they have lower buffering capacity. Organic matter also influences the amount of lime needed. Soil tests take these factors into account when making recommendations.
Frequently Asked Questions (FAQs)
Can I just sprinkle lime on top of the soil and hope for the best?
No. While sprinkling lime on top of the soil is a starting point, it’s not the most effective way to raise soil pH. For optimal results, you need to ensure the lime is watered in thoroughly to reach the root zone. If your soil is compacted, it’s best to lightly scratch it into the top inch or two of soil without disturbing plant roots, before watering.
How long does it take for lime to change the soil pH?
The time it takes for lime to change the soil pH depends on the type of lime, soil type, and weather conditions. Pulverized lime typically works faster than pelleted lime, and warm, moist conditions promote faster reactions. You should see noticeable changes within a few weeks to a few months, but it may take a year or more for the pH to fully stabilize.
What if I accidentally get lime on my plant’s leaves?
If you accidentally get lime on your plant’s leaves, immediately rinse them thoroughly with water. Lime dust can cause leaf burn, so prompt action is important. Use a gentle spray of water to avoid damaging the leaves.
Can I use lime around my acid-loving plants?
No, you should never use lime around acid-loving plants like blueberries, azaleas, rhododendrons, and camellias. These plants thrive in acidic soil, and lime will raise the pH, making it difficult for them to absorb essential nutrients. This can lead to chlorosis (yellowing of leaves) and eventual decline.
How do I know how much lime to apply?
The best way to determine how much lime to apply is to conduct a soil test. Soil test results will provide the current pH level and recommendations for lime application based on the specific needs of your soil and plants. Local agricultural extension offices typically offer soil testing services.
Is dolomitic lime better than regular lime?
Dolomitic lime contains both calcium and magnesium carbonate, while regular lime contains only calcium carbonate. If your soil is deficient in magnesium, dolomitic lime is the better choice. Otherwise, either type of lime will work to raise the pH. A soil test will help determine if you have a magnesium deficiency.
Can I use wood ashes instead of lime?
Wood ashes can be used as a soil amendment to raise pH, as they contain calcium carbonate. However, their composition and effectiveness can vary widely depending on the type of wood burned. Always use wood ashes sparingly and avoid using ashes from treated wood. It is best to still test your soil pH before adding anything. Wood ashes will also add potassium to the soil.
What is the best time of year to apply lime?
The best time of year to apply lime is in the fall or early spring, when the soil is moist and there is ample time for the lime to react with the soil before planting season. However, lime can be applied at any time of year as long as the soil is not frozen and plants are actively growing.
How often should I apply lime?
The frequency of lime application depends on several factors, including soil type, rainfall, and the types of plants being grown. Conduct soil tests every one to three years to monitor the pH and determine if additional lime is needed.
Can I apply lime and fertilizer at the same time?
It is generally not recommended to apply lime and fertilizer at the same time. Lime can react with some fertilizers, reducing their effectiveness. It’s best to apply lime first and allow it to react with the soil for a few weeks before applying fertilizer. Phosphorus availability is particularly affected by high soil pH.
What are the signs that my soil needs lime?
Signs that your soil may need lime include: poor plant growth, yellowing of leaves (chlorosis), stunted roots, and a high incidence of disease. Soil testing is the most reliable way to determine if lime is needed.
Will adding lime hurt my earthworms?
When used properly, lime is not harmful to earthworms. Earthworms prefer slightly acidic to neutral soil, and lime can help create a more favorable environment for them. However, excessive lime application can create alkaline conditions that are detrimental to earthworms. So, follow soil test recommendations carefully.