How to Fertilize Vegetable Garden:
Compost, Manure, and Organic Food
★ SaveLearning how to fertilize vegetable garden beds starts with the soil. Feed the soil with compost and well-aged manure, and the soil feeds your plants.
Most home gardens need only two things: plenty of organic matter every year, and a little extra food for hungry crops during the season. This guide on how to fertilize vegetable garden beds covers both, with free charts to print.
From My Garden
We always had plenty of well-aged manure on our farm, from our sheep and cows. Now we have turned most of our farmland into a hazelnut orchard, and we get a load of aged manure from our neighbor who raises cattle. He is glad to get rid of it, and we are happy to take it!
We still have hens and a rooster, but we miss seeing the little lambs romping in the fields in the springtime.
We put the aged manure on our garden in the late fall, so there is plenty of time for the winter rains to wash some of the nutrients into the soil. When we work up our garden in late spring or early summer, it all gets turned and mixed into the soil.
We have never had to add any chemical fertilizer to our gardens.
Charlotte
Make your own fertilizer
Mix a simple, all-purpose organic fertilizer for your vegetable garden.
Organic Fertilizer RecipeOn This Page
Free Soil and Fertilizer Charts
Click a chart to download it, then print it or save it to Pinterest.
Start with a Soil Test
The most important step in learning how to fertilize vegetable garden soil is knowing what it needs. Your county Extension office offers low-cost soil tests that show pH and nutrient levels, and tell you exactly what to add.
Vegetables like a slightly acid, loose, crumbly soil with a pH of about 6.0 to 7.0. Test every few years, or whenever plants struggle for no clear reason.
N-P-K: What Plants Need
Every fertilizer label lists three numbers: nitrogen (N), phosphorus (P), and potassium (K). A 10-10-10 fertilizer has 10% of each.
| Nutrient | What it does | Signs of shortage | Organic sources |
|---|---|---|---|
| N Nitrogen | Green, leafy growth | Pale, yellow lower leaves; slow growth | Aged manure, blood meal, alfalfa meal, fish emulsion, cover crops like clover |
| P Phosphorus | Roots, flowers, and fruit | Purple-tinged leaves; few flowers | Bone meal, rock phosphate |
| K Potassium | Strong stems, disease resistance, sugars and starches | Brown, scorched leaf edges | Wood ash (lightly), greensand, kelp or seaweed |
Plants also need small amounts of calcium, magnesium, and trace minerals. Compost supplies most of these.
Compost: The Best Garden Food
Two inches of compost dug in each year is the best thing you can do for a vegetable garden. It feeds plants slowly, helps sandy soil hold water, and loosens heavy clay.
Compost improves soil, but it isn't a complete fertilizer. Knowing how to fertilize vegetable garden crops during the season fills the gap. Heavy feeders like tomatoes, corn, and squash often need a little extra during the season.
For good compost, mix "browns" and "greens." Browns (dry leaves, straw, shredded paper) are high in carbon; greens (grass clippings, kitchen scraps, fresh manure) are high in nitrogen. Aim for about 2 to 3 parts browns to 1 part greens. See compost bin plans.
Using Manure as Fertilizer
Always age manure before using it. Fresh manure can burn plants with ammonia and may carry weeds and germs. Compost it for 6 months to a year, until it's dark and crumbly with no smell.
- "Hot" manures (horse, rabbit, sheep, chicken) are high in nitrogen and must be aged.
- "Cold" manure (cow) is wetter and lower in nitrogen.
- Spread it in fall and let winter rains work it in, then mix it into the soil in spring.
- Never use dog, cat, or pig manure on vegetables. They can carry parasites and diseases that spread to people.
- Ask local farms and stables; many are glad to give away aged manure.
See horse manure compost.
Cover Crops and Green Manure
★ SaveA cover crop is grown to feed the soil, not to eat. Planted when a bed would sit bare, it adds organic matter, stops erosion, and smothers weeds. When it's turned into the soil, it's called green manure.
- Clover and hairy vetch add nitrogen, great before heavy feeders like tomatoes and corn.
- Field peas add nitrogen and grow fast for a fall or winter cover.
- Rye, oats, and annual ryegrass hold soil and stop weeds over winter.
- Buckwheat is ready to turn under in 4 to 6 weeks, perfect for a summer gap.
- Mustard helps suppress some soil pests and diseases.
Turn cover crops under before they go to seed, or they become weeds. Don't let mustard seed, or you'll be pulling it forever! See cover crops for vegetable gardens.
Other Natural Fertilizers
- Seaweed and kelp: rich in trace minerals; use any time as a plant booster.
- Blood meal and fish emulsion: quick nitrogen for leafy crops.
- Bone meal and rock phosphate: phosphorus for roots and fruit.
- Greensand: slow-release potassium and minerals.
- Wood ash: adds potassium and raises pH; use lightly, and never coal ash.
- Rock dust: can correct some mineral shortages.
- Leaf mold: leaves composted for a year make a great soil conditioner and mulch.
- Compost tea: a quick liquid feed. See how to make compost tea.
When and How to Fertilize Vegetable Garden Beds
- Before planting: dig in 2 inches of compost or aged manure, plus any amendments your soil test calls for.
- Side-dress during the season: spread compost or a balanced organic fertilizer along the rows, a few inches from the stems, then water it in. It also works as mulch.
- Heavy feeders (tomatoes, corn, squash, cabbage family) benefit from a side-dressing when they start to flower or fruit. See fertilizing tomatoes.
- Light feeders (beans, peas, carrots, radishes, herbs) need little extra; too much nitrogen means leaves instead of crops.
- Containers need regular feeding, since nutrients wash out every time you water.
- Don't overdo it. Too much fertilizer burns roots and builds up salts.
Source: Texas A&M AgriLife Extension.
Building Soil Without Digging
Heavy tilling breaks up the helpful fungi and microbes that feed your plants. Tillers are handy for big gardens, but in smaller beds you can build soil from the top down.
Lasagna gardening: lay down wet layers of cardboard or newspaper, then alternate layers of greens (grass clippings, kitchen scraps, manure) and browns (dry leaves, straw), building to 18 inches or more. Let it settle for several weeks, or plant right into a layer of compost on top. See no-dig gardening.
A Bit of Fertilizer History
In the 1800s, scientists Justus von Liebig and Humphry Davy showed that plants grow better when soil is fed with phosphates and nitrates. That started a rush for old bones to grind into bone meal, and Liebig accused British merchants of digging up Europe's battlefields to find them!
"Of all the delightful gifts that vegetable gardening provides, it is the anticipation we often enjoy the most." ~ Charlotte
Fertilizer Questions
- What is the best fertilizer for a vegetable garden?
- Compost and well-aged manure, dug in every year, plus a balanced organic fertilizer for heavy feeders during the season.
- Do I need chemical fertilizer?
- No. Many gardeners grow great vegetables with only compost, aged manure, and cover crops.
- Can I use fresh manure?
- Not on growing vegetables. Age it 6 months to a year first, or spread it in fall so it breaks down over winter.
- How often should I fertilize?
- The simplest rule for how to fertilize vegetable garden beds: add compost once a year before planting. Side-dress heavy feeders once or twice in the season. Containers need feeding every 2 to 3 weeks.
- What do the three numbers on fertilizer mean?
- The percentages of nitrogen, phosphorus, and potassium (N-P-K).
More: University of Georgia: Compost enriches soil but doesn't replace fertilizer.
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