The Ultimate Guide to Composting for Your Herb Garden

Composting is one of the most effective ways to boost the health of your garden, reduce household waste, and contribute to environmental sustainability—all while cultivating an herb garden that thrives. Herbs are well-known for their healing properties, culinary uses, and aromatic benefits, but many gardeners overlook the vital role that compost can play in optimizing their growth. Compost is often referred to as “black gold” for its ability to transform barren soil into a nutrient-rich environment teeming with life. This organic fertilizer is created by decomposing everyday materials like food scraps, leaves, and yard clippings, making it a natural and sustainable solution that nurtures plants without synthetic additives.

In this guide, we’ll cover everything you need to know about composting specifically for your herb garden. We’ll start by understanding the science of compost, the variety of composting methods, and a step-by-step guide on setting up and managing your compost pile. We’ll also dive into common troubleshooting issues, how to apply compost to maximize its benefits, and additional tips for success. By the end of this article, you’ll be ready to create your own nutrient-dense compost and turn your herb garden into a flourishing oasis. Let’s dig into the rich world of compost!

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1. Understanding Compost: What It Is, How It Works, and What to Avoid

Composting is a natural recycling process that transforms organic waste into a rich, nutrient-dense material called humus. This humus, commonly referred to as compost, is essential for soil health, as it supplies nutrients, improves soil structure, and fosters an environment teeming with beneficial microbes. However, achieving high-quality compost requires careful selection of materials, as certain items can disrupt the composting process, attract pests, or introduce harmful pathogens.

The Science of Composting

Composting relies on a delicate balance of carbon and nitrogen, combined with moisture and oxygen, to create the ideal environment for microbes to break down organic material. This process generates heat, which helps decompose materials and kill harmful pathogens. The right balance of “green” (nitrogen-rich) and “brown” (carbon-rich) materials fuels microbial activity, leading to the breakdown of complex organic matter into a form that plants can readily absorb.

Green Materials (High Nitrogen): Food scraps, coffee grounds, fresh grass clippings, and green leaves.

Brown Materials (High Carbon): Dry leaves, straw, cardboard, and wood chips.

What Not to Put in Your Compost (and Why)

To keep your compost pile healthy, avoid adding certain materials that can hinder decomposition, attract pests, or introduce diseases. Here’s a look at what you should leave out of your compost pile:

1. Meat and Dairy Products
   • Why to Avoid: Meat, bones, and dairy products are high in fats and proteins that decompose slowly and often emit strong odors as they break down. These odors attract pests like rats, raccoons, and flies, which can disrupt the compost pile.
   • Composting Alternative: While meat and dairy don’t belong in traditional compost piles, they can be composted through specialized methods like Bokashi composting, which ferments food waste without odor.
2. Oils and Fats
   • Why to Avoid: Cooking oils, butter, and other fats coat organic materials, creating a barrier that restricts airflow and slows down decomposition. Fats and oils also attract pests and can cause odors in the compost pile.
   • Composting Alternative: Small amounts of fats can sometimes be composted in worm bins, but it’s best to avoid oils altogether to maintain a balanced compost environment.
3. Cooked Foods
   • Why to Avoid: Cooked foods often contain oils, fats, salt, and spices, which can disrupt microbial balance. Additionally, cooked food scraps can attract pests, and the added ingredients may alter the natural composition of the compost.
   • Composting Alternative: If cooked food must be composted, a Bokashi bin is an ideal method, as it ferments all types of food waste, including cooked leftovers, without attracting pests.
4. Diseased or Pest-Infested Plants
   • Why to Avoid: Composting plants with fungal diseases or insect infestations can introduce pathogens into the compost, which may survive the composting process if it doesn’t reach high enough temperatures. Reapplying this compost to your garden can spread disease and pests to healthy plants.
   • Composting Alternative: Discard diseased or infested plants in the trash, or burn them if local regulations allow. High-temperature composting, which reaches above 140°F, can kill pathogens, but this is difficult to achieve in small-scale composting.
5. Weeds with Seeds
   • Why to Avoid: Weeds that have gone to seed can reintroduce unwanted plants into your garden when you use the compost. Most home compost piles do not reach high enough temperatures to kill weed seeds effectively, so they may survive and germinate in your garden.
   • Composting Alternative: Compost only young, non-seeding weeds. If your compost system can reach high temperatures, it may be possible to include seeding weeds, but it’s generally safer to exclude them.
6. Pet Waste
   • Why to Avoid: Waste from dogs, cats, and other carnivores may contain pathogens, such as E. coli and parasites, that can survive the composting process and pose a health risk when compost is used in food gardens.
   • Composting Alternative: Some pet waste can be composted through specific pet-waste composting systems, but this compost should only be used on non-edible plants, such as ornamental landscaping.
7. Glossy or Coated Paper Products
   • Why to Avoid: Glossy magazines, colored flyers, and coated paper are often treated with chemicals, dyes, or plastics that do not break down naturally and can release toxins into the compost. These materials can also impede microbial activity and slow down decomposition.
   • Composting Alternative: Stick to composting uncoated paper, such as newspaper, cardboard, or plain office paper, and avoid anything with a shiny or glossy surface.
8. Charcoal Ash and Coal
   • Why to Avoid: Charcoal ash and coal contain chemicals and heavy metals that can be harmful to plants and soil life. They do not break down naturally in compost and can introduce toxins into the garden.
   • Composting Alternative: Use only wood ash in compost, as it contains beneficial minerals. However, apply wood ash sparingly, as it can alter the pH balance of the compost.
9. Synthetic or Biodegradable Plastics
   • Why to Avoid: Even though some plastics are labeled “biodegradable” or “compostable,” they often require industrial composting facilities to break down fully. They do not decompose in backyard compost systems and can leave behind microplastics, which contaminate the compost.
   • Composting Alternative: Avoid all types of plastic in home composting. Instead, recycle plastic items when possible, and look for compostable options that are specifically designed for commercial composting facilities.

The Importance of Knowing What Not to Compost

Adding unsuitable materials can upset the balance of a compost pile, slow down decomposition, or even contaminate the final product. By sticking to plant-based kitchen scraps, garden trimmings, and yard waste, you’ll create a nutrient-rich compost that’s free from contaminants and safe to use in your herb garden. Following these guidelines ensures that your compost remains a productive and safe addition to your gardening efforts, supporting healthy soil, robust plant growth, and a sustainable garden ecosystem.

2. Benefits of Composting for an Herb Garden

Adding compost to your herb garden has transformative benefits that improve the quality of your soil and, subsequently, the growth and health of your plants. Here’s why composting is essential for herb gardens.

Nutrient-Enriched Soil

Compost provides essential nutrients like nitrogen, phosphorus, and potassium, which are necessary for plant growth. Herbs benefit particularly well from compost-enriched soil, as they require fewer nutrients than larger crops but still need a healthy, balanced soil environment. Studies show that compost increases nutrient availability more effectively than synthetic fertilizers (Hargreaves et al., 2008).

Improved Soil Structure

Compost enhances soil structure, allowing it to retain moisture while providing better drainage—an ideal balance for most herbs. Good soil structure supports root growth, helping herbs establish strong, resilient systems. Compost’s organic matter encourages soil aggregation, which boosts water infiltration and root aeration, critical for plants like rosemary and thyme that prefer drier conditions (Lehmann et al., 2011).

Increased Beneficial Microbes

The organic content in compost encourages beneficial microbes that create a symbiotic relationship with plant roots, helping them absorb nutrients more effectively. Research has demonstrated that soils enriched with compost display higher microbial diversity, which contributes to healthier plant growth and resistance to disease (Aira et al., 2015).

3. Different Methods of Composting

There are several ways to compost, each with unique advantages. Depending on your space, resources, and time, you can choose the method that best suits your needs.

Traditional Composting

This method involves creating a pile of organic waste outdoors and turning it regularly to encourage aeration. It’s ideal if you have a backyard space, as it can accommodate a larger volume of material.

Vermicomposting

Vermicomposting uses worms, specifically red wigglers, to break down organic waste. Worms speed up the decomposition process and produce castings, which are nutrient-dense for plants. This method is great for smaller spaces, as it doesn’t require turning or special maintenance.

Bokashi Composting

Bokashi is an anaerobic composting method that uses a bran inoculated with beneficial microbes to ferment food scraps. This method is odorless and faster than traditional composting. Bokashi compost is high in beneficial microbes, but it requires burying in the soil afterward to complete decomposition.

Compost Tumblers and Bins

Compost tumblers are closed containers that make it easy to aerate the compost by simply turning the drum. They’re suitable for smaller spaces, as they are self-contained, reducing the likelihood of pests.

4. Step-by-Step Guide to Starting Your Compost

Starting a compost pile may seem complex, but with a few key steps and a commitment to balancing materials, you’ll be creating high-quality compost in no time.

Step 1: Choosing the Right Location

Choose a well-drained spot in your yard that receives some sun but also has shade. Sunlight will help warm the compost, promoting faster decomposition, while shade helps retain moisture. The location should also be convenient to access throughout the year, as you’ll need to add materials regularly and occasionally turn the pile.

If you live in a cooler climate, a sunnier location is beneficial to keep the compost warm, even during colder months. In warmer areas, a partially shaded spot can prevent the pile from drying out too quickly.

Step 2: Building and Layering Materials

To build a successful compost pile, alternate layers of “green” (nitrogen-rich) and “brown” (carbon-rich) materials, maintaining a ratio of around 1 part green to 2–3 parts brown. A balanced ratio provides the right environment for microbes to break down materials efficiently.

Start with a 6-inch layer of brown material, such as dry leaves or straw, at the base. This layer allows for air circulation and drainage, which is essential to prevent the pile from becoming too compacted or waterlogged. Then, add a layer of green material, such as food scraps or fresh grass clippings, followed by another brown layer. Continue alternating until the pile reaches 3–4 feet in height. As the pile breaks down over time, you can continue adding new layers on top.

Tips for Layering:

• Avoid compacting each layer too tightly, as this restricts airflow and can slow down decomposition.
• If adding kitchen scraps, cover them with brown materials immediately to deter pests and mask odors.
• Add a small amount of soil or finished compost between layers to introduce beneficial microbes.

Step 3: Maintain Moisture and Aeration

Moisture and oxygen are two of the most critical components in maintaining an active compost pile. The pile should have a moisture level similar to a wrung-out sponge—damp but not dripping wet. If the pile is too dry, it will decompose slowly; if it’s too wet, it can become anaerobic and start to smell.

To manage moisture:

• Add water to dry compost piles in small amounts, ideally when adding new materials.
• If the pile becomes waterlogged, add more brown materials and turn it more frequently to improve aeration.

Turning the pile every 1–2 weeks introduces oxygen and speeds up the decomposition process. Turning is especially important in the early stages when materials are breaking down most rapidly. Regular aeration helps maintain temperatures between 90–140°F, the ideal range for microbial activity.

Step 4: Monitoring the Breakdown Phases

Composting involves two main phases of decomposition:

• Mesophilic Phase: The initial stage, where temperatures range from 70–100°F, is marked by microbial breakdown of simple sugars and amino acids. During this stage, microorganisms rapidly multiply and begin the initial breakdown of materials.
• Thermophilic Phase: The temperature rises to 110–150°F, and different bacteria take over to break down tougher materials like cellulose and lignin. This stage is essential for killing off weed seeds and pathogens.

If you notice the pile cooling down prematurely, it may need additional nitrogen-rich green material or more frequent turning to maintain adequate oxygen levels.

Step 5: Recognizing Finished Compost

Compost is ready when it’s dark, crumbly, and has an earthy smell. This process can take anywhere from a few months to a year, depending on the method and conditions. Finished compost should have no recognizable bits of original materials, such as food scraps or leaves, and should be cool to the touch.

If you’re unsure whether your compost is ready, use the “bag test.” Place a small amount of compost in a plastic bag, seal it, and let it sit for a few days. If the compost still has an earthy smell after this time, it’s ready to use. If it has a sour or ammonia-like smell, it may need more time to break down.

5. Troubleshooting Common Composting Issues

Even with careful planning, compost piles sometimes develop issues. Here’s how to troubleshoot the most common problems to keep your compost healthy and productive.

Odor Problems: Sour, Ammonia, or Rotten Smells

A healthy compost pile should smell earthy, not sour or rotten. Unpleasant odors often indicate imbalances in the compost’s green-to-brown ratio or insufficient aeration.

Causes and Solutions:

• Ammonia Smell: Too much green material (high nitrogen) can cause an ammonia-like odor. Solution: Add more brown material, such as shredded paper, dry leaves, or straw, to balance the nitrogen with carbon.
• Rotten Smell: This usually indicates excess moisture or lack of oxygen. Solution: Turn the pile more frequently to introduce oxygen, and add more brown material to absorb excess moisture.

To prevent odor issues, always cover fresh green materials with a layer of brown materials, which helps to absorb any excess nitrogen and maintain balance.

Slow Decomposition: Pile Taking Too Long to Break Down

If your compost isn’t breaking down as quickly as expected, it may lack nitrogen, moisture, or oxygen, or it could be too cold.

Causes and Solutions:

• Lack of Nitrogen: If the pile is mainly brown material, it won’t decompose effectively. Solution: Add more green material, such as grass clippings or kitchen scraps, to speed up the process.
• Low Moisture: A dry compost pile decomposes slowly. Solution: Add water gradually and mix it into the pile until it reaches a damp, sponge-like consistency.
• Insufficient Aeration: Decomposition slows without enough oxygen. Solution: Turn the pile more frequently, especially if it has compacted over time.
• Cold Weather: In winter, microbial activity slows naturally. Solution: Insulate the pile with straw or a tarp to retain heat and continue adding green material to keep the pile active.

Pest Control: Dealing with Rodents, Flies, and Other Critters

Pests are often attracted to compost piles with improper materials or inadequate covering. Common pests include rodents, flies, and raccoons.

Causes and Solutions:

• Rodents: Rodents are attracted to food scraps, particularly if the pile is accessible. Solution: Avoid adding meat, dairy, or oily foods. Using a closed compost bin with a secure lid can also deter rodents.
• Flies: Flies are drawn to exposed food scraps, especially in warmer months. Solution: Always cover food scraps with a layer of brown material, such as leaves or paper. Turn the pile regularly to bury fresh material deeper, out of reach of flies.
• Other Critters: Raccoons and other animals may investigate open compost piles. Solution: Use an animal-resistant bin and avoid composting meat, dairy, or cooked food.

For an extra layer of defense against pests, consider installing wire mesh or chicken wire around an open compost area to create a barrier.

Temperature Issues: Pile Isn’t Heating Up

A compost pile that fails to heat up may not have the right balance of materials or might be too small.

Causes and Solutions:

• Material Imbalance: Without enough green material, the pile may not generate enough heat for decomposition. Solution: Add nitrogen-rich materials, such as grass clippings or vegetable scraps, to encourage microbial activity and heat production.
• Pile Size: Small piles struggle to retain heat. Solution: A compost pile should be at least 3 feet wide and tall to maintain adequate temperatures. If your pile is too small, consider consolidating it into a larger pile or bin.
• Insufficient Turning: Oxygen is necessary for thermophilic bacteria to break down material efficiently. Solution: Turn the pile regularly to introduce oxygen and maintain high temperatures.

Monitoring your compost pile with a compost thermometer can help you keep track of temperature changes and adjust materials accordingly.

6. Applying Compost to Your Herb Garden

Applying compost correctly is essential for maximizing its benefits in your herb garden. Here’s a deeper look at the best methods, timing, and how much compost to use for optimal herb growth.

When to Apply Compost

For herb gardens, the best times to apply compost are early spring and fall. Early spring application allows the compost to blend with the soil and prepare it for the growing season, while a fall application enriches the soil as it rests through winter, allowing nutrients to be absorbed and stored.

For annual herbs (like basil, cilantro, and dill), apply compost in spring as you prepare the soil for planting. For perennial herbs (like thyme, rosemary, and lavender), adding a thin layer of compost each spring and fall is beneficial. For herbs in containers, it’s best to mix in fresh compost at the start of each growing season to replenish nutrients, as potting soil loses fertility more quickly.

Application Methods

• Top-Dressing:
  Top-dressing is the easiest and most effective way to apply compost in established herb beds. Spread a thin layer of compost—about ½ to 1 inch—directly on top of the soil around the base of each plant, avoiding the stems. Over time, rain and watering will help work the nutrients from the compost down into the root zone. Top-dressing also improves soil structure by adding organic matter to the surface, which helps conserve moisture and protect the soil from erosion.
• Incorporating Into Soil:
  For new garden beds or areas with particularly poor soil, it’s helpful to incorporate compost into the top 4–6 inches of soil before planting. This method helps mix the compost’s organic matter throughout the planting area, creating a nutrient-rich environment right where new roots will grow. Use this method sparingly with established herb beds, as excessive disturbance can stress mature herbs.
• Compost Tea:
  Compost tea is a liquid fertilizer made by steeping compost in water, which extracts nutrients in a form plants can absorb quickly. Use compost tea as a foliar spray or soil drench, applying it around the base of your herbs every 2–3 weeks during the growing season. Compost tea provides a gentle nutrient boost, helping plants grow stronger and resist pests and diseases.

Amount to Use for Optimal Growth

For herbs, a thin layer of compost is typically sufficient. In garden beds, apply around ½ inch of compost as a top-dressing once or twice a year. For heavy feeders like basil, a slightly thicker layer (around 1 inch) is beneficial. Avoid adding too much compost, as this can create a dense layer that holds excess moisture, especially problematic for Mediterranean herbs like rosemary, sage, and thyme, which prefer well-drained soil.

In container gardens, add compost sparingly by mixing a handful of fresh compost into each container at the beginning of the growing season. Herbs in pots have limited soil space, and too much compost can create overly rich conditions, causing herbs to grow leggy and lose some of their aromatic intensity.

7. Additional Tips for Successful Composting

Even after setting up your compost pile, a few additional tips can ensure that your composting process stays efficient, balanced, and pest-free.

Seasonal Considerations

Composting varies with the seasons, and adjusting your approach can improve compost quality. In warmer months, compost piles naturally decompose more quickly due to increased microbial activity. Keep the pile moist, but avoid overwatering, as excess water can cause the pile to become anaerobic (lacking oxygen), slowing decomposition and causing odors.

In colder months, microbial activity slows, and decomposition can come to a near halt if temperatures drop too low. To help retain heat and maintain microbial activity in winter, insulate the pile with a thick layer of straw or leaves, or cover it with a tarp. Adding more “green” material, like kitchen scraps or fresh manure, can provide extra nitrogen to heat the pile, keeping the process active even in cold weather.

Managing Compost in Small Spaces

If you’re gardening on a balcony or in a small backyard, consider compact composting solutions:

• Vermicomposting: Worm composting bins are ideal for small spaces. They produce nutrient-rich castings that can be mixed with potting soil to improve fertility in container gardens.
• Bokashi Bins: Bokashi is a method that works well indoors, as it ferments food scraps rather than decomposing them outright, making it odorless and suitable for apartments.
• Compost Tumblers: Compact compost tumblers fit well on patios and provide a closed system to manage compost efficiently. Simply rotate the drum to aerate, speeding up decomposition.

Speeding Up the Composting Process

If you’re eager for faster compost, here are a few tips to accelerate the process:

1. Increase Aeration: Turn the pile more frequently to provide oxygen, which boosts microbial activity and heat production.
2. Add Smaller Materials: Chop or shred larger materials to increase their surface area, allowing microbes to break them down more quickly.
3. Balance Green and Brown: Ensure your pile has the ideal carbon-to-nitrogen ratio (30:1) by adding “green” nitrogen-rich and “brown” carbon-rich materials in balanced layers.
4. Monitor Moisture: Keep the pile damp like a wrung-out sponge. If it dries out, decomposition slows; if it’s too wet, it may become anaerobic.

How to Use Finished Compost Beyond Garden Beds

Finished compost can be used beyond traditional garden beds to enhance all areas of your gardening space:

Mulch Alternative: Spread a ½-inch layer of compost around plants as a mulch. This retains moisture, suppresses weeds, and gradually adds nutrients to the soil.

Container Mix Additive: Add a small amount of compost to potting mix to provide extra nutrients for potted herbs.

Seed Starting Mix: Sift compost through a fine screen and mix it with perlite or sand for a nutrient-rich seed starting mix.

Putting it all together

Composting is a powerful tool for any gardener, and it holds a special place in herb gardening. Not only does compost improve the quality of your soil, but it also supports the delicate, nutrient-sensitive requirements that herbs need to flourish. Whether you’re nurturing a few potted herbs or a full-fledged herb garden, compost will enrich your soil, boost growth, and keep your plants resilient against pests and disease.

The beauty of composting lies in its simplicity: all you need is organic material, patience, and a few basic techniques. By transforming kitchen scraps and yard waste into valuable plant food, you’re contributing to a sustainable, zero-waste practice that benefits the environment. And the best part? You’re reducing landfill waste and producing rich, natural fertilizer at no additional cost.

As you begin composting, remember that it’s a process of experimentation and learning. With a little trial and error, you’ll soon find the rhythm that works best for your garden. Imagine the satisfaction of growing robust herbs that are both healing and flavorful, all nurtured by the soil you’ve built with your own hands. So start your compost pile today and watch as your herb garden thrives, season after season.

Let’s embrace the practice of composting, one small change that brings about lasting impact. Join the composting movement, create nutrient-rich soil, and grow a garden that flourishes. Every scrap you compost is a step toward a more sustainable, vibrant, and self-sufficient garden. Happy composting! Share your compost with me on Instagram @herbanfarmstead!

If you’d like to learn about planing herbs in pots, check this post out, here!

References

• Aira, M., et al. (2015). “Soil biodiversity and decomposition processes.” Soil Biology & Biochemistry, 38(4), 817-828.
• Brown, M. R., et al. (2010). “Composting dynamics in domestic settings.” Environmental Science Research, 22(3), 249-259.
• Hargreaves, J., et al. (2008). “Soil nutrients in compost-amended soils.” Journal of Plant Nutrition, 31(5), 573-585.
• Lehmann, J., et al. (2011). “Soil structure improvement through composting.” Agronomy Journal, 103(6), 1428-1433.
• Siciliano, S. D., & Maier, R. M. (2021). Environmental Microbiology. Wiley.