Natural Garden Fertilizers: The Ultimate Guide to Compost, Manure, Cover Crops, and DIY Feeds
You don't have to buy expensive fertilizers! Your garden will thrive with these DIY versions made from items around your pantry and backyard!
Quick Reference: Natural Garden Fertilizers
- Start with a soil test. Most state extensions process a sample for $15 to $20. Without one, you are guessing at NPK and pH.
- Top 3 by impact: finished compost (1 to 2 inches yearly), composted manure (1/2 inch yearly), and a winter cover crop (clover, rye, or vetch).
- Quick boosts: grass-clipping mulch (free nitrogen), fish emulsion (fast nitrogen + trace minerals), worm castings (slow micronutrients).
- Cost-effective DIY: compost tea, comfrey tea, and onion-skin/banana-peel ferment.
- Tool: the Almanac’s Best Days planting + fertilizing calendar for moon-aligned feeding windows.
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A natural garden fertilizer feeds the soil organisms that feed the plants, instead of feeding the plants directly. That distinction is the entire reason a thriving organic garden out-yields a synthetic one over the long run. This guide covers the five fertilizer categories every home gardener should know (compost, manure, cover crops, mineral amendments, and liquid feeds), the NPK numbers extension labs recommend for each, and a season-long calendar that mirrors what the Farmers’ Almanac Best Days have tracked for over 200 years.
The 5 Categories of Natural Fertilizer (and What Each Does)
Per UMN Extension, almost every natural fertilizer falls into one of five buckets. Mixing across categories outperforms relying on any single one.
- Bulk organic amendments. Compost, composted manure, leaf mold. Slow-release NPK + organic matter that improves soil structure for years. The single highest-impact intervention.
- Cover crops. Clover, vetch, winter rye, buckwheat. Fix nitrogen, build biomass, suppress weeds, feed soil microbes through living roots.
- Mineral amendments. Rock phosphate (slow P), greensand (slow K), gypsum (Ca + S), kelp meal (trace minerals). Use to correct deficits a soil test identifies.
- Liquid feeds. Fish emulsion, compost tea, comfrey tea, seaweed extract. Fast-acting, useful mid-season for hungry crops like tomatoes and corn.
- Mulches that double as feeds. Grass clippings, shredded leaves, straw. Slowly mineralize into N and K while suppressing weeds and conserving moisture.
How to Read Your Soil Test (NPK and pH, Plainly)
USDA NRCS notes the single biggest cause of fertilizer waste in home gardens is fertilizing without a soil test. The test typically costs $15 to $20 from a state extension lab and reports four numbers.
- pH. Vegetables grow best at 6.0 to 7.0. Below 6.0, add agricultural lime. Above 7.5, add elemental sulfur. Per UMN Extension, ignore both NPK and the rest if pH is off.
- N (nitrogen). Soil tests rarely give a precise reading; estimate from prior crop and organic matter. Add via compost, blood meal, or a legume cover crop.
- P (phosphorus). Read as ppm. Below 20 ppm: add rock phosphate or bone meal. Above 50 ppm: stop adding (most US soils are P-excessive).
- K (potassium). Below 100 ppm: add wood ash (if pH allows) or greensand. Above 200 ppm: hold off.
- Organic matter (OM). Target 4 to 6 percent. Below 3: prioritize compost. Above 8: you are doing fine, slow the inputs.
Natural Fertilizers, Soil, and DIY Recipes (The Detail Sections)
Below are the original detail sections, with the soil-test step, fertilizer types, specific-need recommendations, DIY options, and balanced-ecosystem notes preserved in full.
What are natural fertilizers?
Natural fertilizers, unlike synthetic ones, come from natural materials and improve the overall health of your soil. This translates to stronger plants, better yields, and a more vibrant garden ecosystem.
Why use natural fertilizers?
There are many compelling reasons to choose natural fertilizers over synthetic options. Here are just a few:
- Improved Soil Health: Natural fertilizers promote the growth of beneficial microbes in the soil, which helps break down organic matter and make nutrients more readily available to plants. This leads to healthier soil that retains moisture more effectively.
- Reduced Environmental Impact: Synthetic fertilizers can leach into waterways, causing harm to aquatic ecosystems. Natural fertilizers, on the other hand, are less likely to pollute and contribute to a more sustainable gardening practice.
- Safety for Children and Pets: Chemical fertilizers can be harmful if ingested by children or pets. Natural fertilizers pose a much lower risk, making your garden a safer space for everyone.
- Long-Term Benefits: While synthetic fertilizers provide a quick burst of nutrients, they can deplete essential elements over time. Natural fertilizers provide a slow and steady release of nutrients, promoting long-term soil health.
1. Compost
Compost reigns supreme in the world of natural fertilizers. This nutrient-rich material is created by the decomposition of organic matter like food scraps, yard waste, and leaves. Compost feeds the soil microbiome, improves soil structure, and provides a slow-release source of essential nutrients for a wide range of plants.
How to Use Compost:
- Amend your garden beds with a 2-3 inch layer of compost before planting.
- Enrich your potting mix for container plants with compost.
- Apply compost as a top dressing around established plants throughout the growing season.
Pro Tip: Not all compost is created equal. Aim for well-aged compost that has a crumbly texture and a pleasant earthy smell.
2. Grass Clippings
A readily available source of nitrogen, grass clippings can be a valuable addition to your garden’s fertilizer arsenal. However, there are a few things to keep in mind:
- Fresh vs. Dried: Fresh clippings can mat down and hinder air circulation. Let them dry for a day or two before adding them to your garden.
- Nitrogen Boost: Grass clippings are a green material, high in nitrogen. This is great for leafy vegetables but not ideal for flowering plants that require more phosphorus.
- Herbicide Warning: If you’ve recently treated your lawn with herbicides, avoid using those clippings in your vegetable garden.
How to Use Grass Clippings:
- Spread a thin layer of dried grass clippings around your plants as mulch.
- Add grass clippings to your compost pile for a nitrogen boost.
3. Manure
Manure is a fantastic source of organic matter and nutrients for your garden. However, different types of manure have varying nutrient profiles. Here’s a quick breakdown:
- Cow Manure: A well-rounded fertilizer rich in nitrogen, phosphorus, and potassium. Aged cow manure is best to avoid burning tender plants.
- Chicken Manure: Very high in nitrogen, chicken manure is best composted before using in the garden.
- Horse Manure: A good source of nitrogen and potassium, horse manure heats up as it decomposes, making it ideal for raised beds.
Important Considerations:
- Fresh manure: Fresh manure can be too strong for plants and can harbor weed seeds and pathogens. Always use aged or composted manure.
- Manure source: Be sure to obtain manure from a reputable source that raises animals without antibiotics or growth hormones.
How to Use Manure:
- Aged manure can be dug into your garden beds before planting.
- Create a manure tea by soaking composted manure in water for a few days. Dilute the tea before applying it to your plants.
Beyond the Basics: A World of Natural Options
The world of natural fertilizers extends far beyond our top three contenders. Let’s delve into some unique and effective options you can explore:
- Coffee Grounds: A good source of nitrogen, coffee grounds can add a slight acidity to your soil, making them ideal for acid-loving plants like blueberries and azaleas. However, use them in moderation as too much coffee can impede germination.
- Eggshells: A natural source of calcium, eggshells can help improve cell wall strength in plants and deter some pests like snails and slugs. Crush eggshells before adding them to your garden bed or compost pile.
- Fish Emulsion: Made from pressed fish scraps, fish emulsion is a liquid fertilizer rich in nitrogen and phosphorus. While effective, fish emulsion has a strong odor. Dilute it heavily before applying it to your plants.
- Seaweed Extract: Packed with micronutrients and beneficial kelp, seaweed extract can stimulate plant growth and improve overall plant health. Seaweed extract is available in liquid or powder form.
- Cover Crops: Planting cover crops like clover or ryegrass in your garden beds during the off-season adds organic matter to the soil, fixes nitrogen, and suppresses weeds. Till the cover crops under before planting your main crops.
Microbial Diversity
Microbial diversity plays a crucial role in soil health and plant nutrition. While this article highlights the benefits of natural fertilizers in promoting soil microbial activity, it’s essential to emphasize the importance of fostering diverse microbial communities on a larger. Encouraging microbial diversity through the use of natural fertilizers can enhance nutrient cycling, improve soil structure, and boost plant resilience to diseases and environmental stressors.
Sustainable Packaging and Sourcing
In addition to discussing the benefits and applications of various natural fertilizers, it’s important to address the sustainability of their packaging and sourcing. Choosing products packaged in biodegradable or recyclable materials reduces environmental impact and aligns with eco-conscious gardening practices.
Additionally, sourcing natural fertilizers locally or from reputable suppliers supports sustainable agriculture and reduces carbon emissions associated with transportation. By prioritizing products with transparent sourcing practices and minimal packaging waste, gardeners can make informed choices that contribute to a healthier planet.
Community and Knowledge Sharing
We would like to underscore the role of community and knowledge sharing in sustainable gardening practices. Joining community gardening groups, attending workshops, or participating in online forums provides opportunities to exchange ideas, troubleshoot challenges, and discover new techniques for nurturing thriving gardens.
Collaborative efforts not only foster a sense of camaraderie but also empower individuals to make informed decisions about natural fertilizers, soil health, and ecological stewardship. By engaging with a diverse community of gardeners, enthusiasts can cultivate deeper connections with the land and inspire positive change in your local environment!
A Season-Long Natural Fertilizer Calendar
Built to match the Almanac’s Best Days fertilizing windows and the soil-temperature curve in USDA zones 4 to 7.
- February: get your soil test results back. Order any amendments you will need.
- March: turn finished compost into beds (1 to 2 inches). Apply lime or sulfur if pH is off.
- April: sow cover-crop edges (clover, buckwheat). Plant first peas with rock phosphate.
- May: side-dress tomatoes, peppers, squash with compost + handful of fish meal at planting.
- June to July: mid-season liquid feed (fish emulsion or compost tea) every 2 to 3 weeks for heavy feeders.
- August: final liquid feed for fall crops. Stop nitrogen by month end.
- September: sow winter cover crops (rye, vetch, clover).
- October to November: apply leaf mulch 4 inches deep over all beds. Let it overwinter.
Natural Garden Fertilizers FAQ
What is the best natural fertilizer for a vegetable garden?
Finished compost is the single highest-impact natural fertilizer for a home vegetable garden, full stop. It provides slow-release NPK, micronutrients, soil structure, and feeds the microbial community that makes other nutrients available. UMN Extension recommends 1 to 2 inches turned into beds each spring.
How do I know if my garden needs more nitrogen?
Pale or yellowish leaves on heavy feeders (corn, tomatoes, brassicas), slow growth in late spring despite good water, and a soil test reporting under 4 percent organic matter are all signs of low nitrogen. Side-dress with composted manure or fish emulsion, or plant a legume cover crop the following winter.
Can you over-fertilize with natural fertilizers?
Yes. Too much manure or compost can spike phosphorus and salts to levels that damage seedlings and run off into waterways. Per USDA NRCS, the most common over-application is fresh manure on small gardens; compost it for 6+ months first.
What is the best free natural fertilizer?
Grass clippings used as mulch and shredded leaves in fall. Both add nitrogen and potassium for free as they mineralize. The next-best free input is kitchen-scrap compost, even from a small countertop bin.
Is wood ash a good fertilizer?
Yes for potassium and calcium, with two cautions: wood ash raises pH (avoid on already-alkaline soil) and should only come from clean untreated hardwood. UMN Extension recommends no more than 5 pounds per 100 square feet per year.
How often should you fertilize a vegetable garden?
A compost-rich bed needs little more than a side-dress at planting and a mid-season liquid feed for heavy feeders. Most home gardens are over-fertilized, not under-fertilized. Always retest soil every 2 to 3 years.
Can you make compost tea at home?
Yes. Steep 1 cup finished compost in 1 gallon dechlorinated water for 24 to 48 hours, stirring occasionally. Strain and apply diluted (1 to 5) as a soil drench or foliar spray. UMN Extension notes the evidence for disease suppression is mixed but the nutrient delivery is real.
This article was published by the Staff at FarmersAlmanac.com. Any questions? Contact us at questions@farmersalmananac.com.
- Farmers' Almanac Staff
- Farmers' Almanac Staff
- Farmers' Almanac Staff
- Farmers' Almanac Staff
Hi, can you please help me on Daikon radish ? Which type of fertiliser is good ?
Hi Thanush, We would recommend that you choose fertilizers with phosphorus and potassium for daikon radishes. Try bone meal and/or kelp meal. Please note: excessive nitrogen will encourage lush foliage rather than encouraging root growth (which you don’t want). Any other questions? Let us know! We hope these tips help you! Best wishes from your friends at FA!
Are wood chimney cleanings good as a fertilizer? Thx
Hi Brian, We wouldn’t recommend using random wood chimney cleanings and soot in your garden. But you may burn clean, untreated hardwood in your fireplace to create wood ash fertilizer. The drier the wood, the finer (and better) the ash will be. If you would like more information about this, let us know, and we will share more!
What is best for cucumbers? I’ve never had any trouble until this year with my cucumber plants. They just wilted up and died within 2-3 days. We water them every day as it is dry this year.
Cucumbers do not need a lot of Nitrogen, so all-purpose fertilizer is usually not appropriate. Bone Meal, Worm Castings, Tea leaves or used coffee grounds, and egg shells are all great for cucumbers. Best of luck!
I have one warning about using leaves. We have a ton of trees, so one year I mulched, bagged, and stored leaves in a dark spot over winter to use for my garden. Found out the hard way that vine borers love to live and reproduce in those leaves. No squash for me that year. So just be careful, please.
This is a great reminder! Thank you for sharing.
Seems that with the abundance of invasive plants and a lake with nutrient rich muck could be a win win
Good tips! I’ve been working on my compost bin for 6 months. It’s dry, I think I need to add water perhaps. Your other tips are bang on. No meat, no critters…except the ones you want.
Kumar Medical Care
Great! Thanks for sharing
Very informative, practical advice
Thank you Rob,
Glad you found it useful. Hope you enjoy other articles here as well!
Many of these are simply not true (see coffee grounds, eggshells) in the strict sense. They are long disproved gardening myths. Disappointed to see them here.
What’s best to use on pumpkins?
Composting for vegetable garden