Planning a Successful School & Community Garden Program Summer 2026

Type of Organic Matter

Advantages

Disadvantages

Leaves (uncomposted)

Fresh leaves have more organic material available to soil microorganisms. Soil organisms excrete sticky substances that increase soil aggregation.

May cause a nitrogen deficiency in your plants, because soil microorganisms consume nitrogen as they grow.

Loses volume more rapidly.

*Locally sourced

Shredded Leaves (uncomposted)

Higher surface area further speeds up the process of decomposition.

Organic matter does not last as long in the soil.

Loses volume more rapidly.

*Locally sourced

Leaf Mold 

(partially composted)

Organic matter lasts longer in the soil since much of the decomposition has already occurred.

Contains fewer weed seeds and plant disease organisms. 

Loses volume less rapidly.

Less food for soil microorganisms, so less aggregation will occur with an application of leaf mold as opposed to uncomposted leaves.

Straw

Quick release of nutrients and suppression of weeds. 

Easy to spread.

Decomposes rapidly, so you will need to replenish it more often.

There may be grain seed heads in the mulch, which can sprout. 

Not ornamental.

Can hide insect pests.

Hay

Quick release of nutrients.

Easy to spread.

May include weed seeds, which can sprout.

Not ornamental.

Wood Chips

Slow release of nutrients as they decompose over the course of ~2 years.

Weed suppression.

Uncomposted wood chips can sequester nitrogen in the soil and cause nitrogen deficiency in plants. Can also interfere with soil and water movement. Only use composted wood chips. May attract termites.

Ramial Wood Chips

Because they are made from small, fresh branches, they contain more nutrients, sap, and live buds. Can moderate extreme soil pH. Weed suppression.

Have the capacity to sequester nitrogen in the soil for about a year.

Compost

Prevents water loss.

Insulates plant roots.

Environmentally friendly and can easily be locally sourced.

Decomposes quickly, may need to be replenished often.

Unless applied thickly, may not suppress weed growth.

Cow Manure

Weed suppression and improvement of soil moisture capacity.

Applying too much may reduce crop yield and lead to nitrogen leaching.

Potential to introduce human pathogens to the soil.

Horse Manure

Weed suppression and improvement of soil moisture capacity.

May contain viable weed seeds, as they pass directly through a horse’s digestive system.

Potential to introduce human pathogens to the soil.

Chicken Manure

Higher in nutrients than cow and horse manure, can be applied in smaller amounts. Improves soil  moisture capacity.

May be high in salts.

May burn plants.

Potential to introduce human pathogens to the soil.

Rabbit Manure

Higher in nutrients than cow, horse, and chicken manure, can be applied in smaller amounts.

Does not need to be composted, unlike the other kinds of manure listed. 

Will not burn plants.

Potential to introduce human pathogens to the soil.

Extremely nitrogen-rich; potential for nitrogen leaching.

Amendment

Primary Use

N-P-K ratio

Notes/More Information

Alfalfa Meal

Highly recommended for roses, but also used for vegetables, shrubs, herbs, etc.

2.5-0.5-2.5

Good vegan alternative to fish and blood meal.

Azomite

Root and plant system growth, crop yield and quality, remineralizing depleted soil.

0-0-0.2

Mined exclusively in central Utah from an ancient volcanic eruption, contains many minerals and trace elements.

Bat Guano

Vegetable growth, fruit and flower development

7-3-1

Blood Meal

Nitrogen-demanding plants, such as broccoli, spinach, corn, leafy greens

12-0-0

Bone Meal

Flowering plants, trees, ornamentals; phosphorus boosts root development

3-15-0

Cottonseed Meal

Plants that thrive in more acidic soils: berries, flowering shrubs, evergreens, etc.

6-2-1

Crab Meal

Vegetable gardens, flower beds, field crops

4-3-0

Coarse texture is helpful for aerating soil and drainage.

Feather Meal

Corn, tomatoes, other vegetables harvested in fall

12-0-0

Nitrogen is slow-release.

Fish Bone Meal

Root vegetables, since phosphorus helps root growth

4-12-0

Fish Meal

Promoting soil microbial life and root development

8-6-0

Greensand

Insect Frass

General nutrition

3-1-1

Derived from larvae manure, exoskeletons of black soldier flies.

Kelp Meal

Greater fruit and vegetable yields

1-0.1-2

Neem Seed Meal

Encouraging optimum plant development

6-1-2

Also referred to as neem cake.

Rock Phosphate

Long-term plant productivity, preventing calcium deficient soils, flowering plants

0-3-0

Seabird Guano

Enhance bacterial activity in soil, root and bloom development

0-11-0

Shrimp Meal

Garden vegetables, flowers, herbs

6-6-0

Breaks down rapidly in soil, quick release of nutrients.

Soybean Meal

Vegetables, flowers, lawns and landscaping

7-1-2