The Basics of Fertilizers

General Vegetable Fertilizer Schedule


Vegetable Feeding Schedule to guide your fertilizing routine throughout the growing season. This plan is designed for Zone 6–10 gardens but can be adjusted for your specific zone or crop needs.

StageTimeframeWhat to ApplyWhy
Pre-Planting2–4 weeks before sowing/transplantingCompost or aged manure; balanced fertilizer (10-10-10)Improves soil structure and provides baseline nutrients
Seedling Stage1–2 weeks after emergence or transplantDiluted liquid fertilizer (fish emulsion, ½ strength synthetic 10-10-10)Encourages early root and leaf development
Vegetative GrowthEvery 2–3 weeks (early growing season)Higher nitrogen (e.g., 20-5-10) or compost teaSupports leafy growth, especially for greens
Pre-Flowering/FruitingWhen buds form (approx. 4–6 weeks in)Low nitrogen, higher phosphorus/potassium (e.g., 5-10-10, bone meal, kelp meal)Promotes blooms, fruits, and strong roots
Fruiting StageEvery 2–3 weeks during fruitingTomato or vegetable fertilizer (e.g., 5-10-10); add potassium if needed (wood ash, kelp)Sustains fruit growth and disease resistance
Late Season2–4 weeks before final harvestCompost tea or mild organic feed (if needed)Helps with final fruit/veg maturity
Post-HarvestAfter final harvestCompost or cover crop (green manure)Replenishes nutrients and prepares soil

Categories of Fertilizers

There are three basic types of fertilizers used in gardening, categorized by their composition and source:

1. Organic Fertilizers

Derived from natural sources, like plants, animals, or minerals. They improve soil structure and microbial activity over time.

Examples:

Compost – decomposed plant matter

Manure – animal waste (chicken, cow, horse, etc.)

Bone meal – ground animal bones (high in phosphorus)

Blood meal – dried animal blood (rich in nitrogen)

Fish emulsion – liquid fish byproduct (balanced nutrients)

Seaweed/Kelp – micronutrient-rich

Pros:

Environmentally friendly

Improves soil health

Slow-release

Cons:

Slower acting

Nutrient content can be variable


2. Inorganic (Synthetic/Chemical) Fertilizers

Manufactured through chemical processes, they provide nutrients in immediately available forms.

Common Types:

Granular fertilizers – slow- or quick-release, applied to soil

Water-soluble fertilizers – mixed with water for fast uptake

Slow-release coated pellets – release nutrients over time

NPK Examples:

10-10-10: Balanced general-purpose

20-5-10: High-nitrogen for leafy growth

5-10-10: For flowering/fruiting plants

Pros:

Fast results

Precise nutrient content

Cons:

Can lead to salt buildup

No improvement to soil structure

Risk of over-fertilization (burning plants)


3. Mixed (Blended) Fertilizers

A combination of organic and inorganic components, designed to balance the benefits of both.

Example:

Organic base with added synthetic NPK for faster action

Pros:

Balanced approach

Improved soil health with quicker results

Cons:

May still contain synthetic chemicals

Cost can be higher than either type alone


Understanding N-P-K:

Most fertilizers list three numbers (e.g., 10-10-10):

N (Nitrogen): Leafy growth

P (Phosphorus): Root development, flowers, fruits

K (Potassium): Overall plant health, disease resistance

Chosen the right one

Simple guide to choosing the right fertilizer based on what you’re growing in your garden:


Vegetable Gardens

Best Type: Balanced or slightly higher phosphorus (P) for root and fruit development
Recommended Fertilizer:

10-10-10 (general purpose)

5-10-10 (better for root crops and fruiting vegetables)

Compost + fish emulsion (organic option)

Tips:

Use a nitrogen-boosting fertilizer early for leafy vegetables like lettuce or spinach.

Switch to phosphorus-heavy formulas when fruits or roots begin developing (e.g., tomatoes, carrots).


Flower Gardens

Best Type: Higher phosphorus for more blooms
Recommended Fertilizer:

5-10-5 or 10-20-10

Bone meal (organic option)

Liquid bloom boosters during flowering stage

Tips:

Too much nitrogen = lush leaves, few flowers.

For continuous bloomers, apply monthly during the growing season.


Herbs

Best Type: Low to balanced nitrogen
Recommended Fertilizer:

5-5-5 or organic compost

Fish emulsion (diluted for tender herbs)

Tips:

Avoid over-fertilizing; strong growth can dilute flavor and aroma.


Fruit Trees & Shrubs

Best Type: Balanced early in the season, more potassium (K) during fruiting
Recommended Fertilizer:

6-2-4 (citrus trees)

10-10-10 or fruit tree spikes

Compost + wood ash (organic potassium source)

Tips:

Apply in early spring and again mid-season.

Mulch with compost for slow nutrient release.


Lawns

Best Type: High nitrogen (N) for green growth
Recommended Fertilizer:

20-5-10

Slow-release lawn fertilizer

Corn gluten meal (organic pre-emergent and N source)

Tips:

Apply in early spring and fall.

Water well after application to prevent burn.


Crop-Specific Notes

Leafy Greens (lettuce, spinach, kale): Focus on nitrogen early; avoid high-P/K blends.

Root Crops (carrots, beets, radishes): Use low-nitrogen, higher phosphorus (5-10-10).

Fruiting Crops (tomatoes, peppers, squash): Start with balanced, then switch to low-N/high-P once flowers appear.

Legumes (beans, peas): Often don’t need added nitrogen—use compost or low-N feed.


Tips for Effective Feeding

Water thoroughly after applying granular fertilizers to prevent burning roots.

Use liquid feed for quick boosts, especially during key growth stages (flowering/fruiting).

Don’t over-fertilize—it can lead to excessive leaf growth and fewer fruits.

Organic growers: Use compost, worm castings, fish emulsion, bone/kelp meal.


Month by Month feeding schedule

Calendar-Based Vegetable Feeding Schedule for Zones 6–10, assuming a spring planting (adjust by 4–6 weeks earlier or later depending on your local climate). This is ideal for most common vegetables like tomatoes, peppers, squash, beans, greens, carrots, etc.


Vegetable Fertilizer Calendar (Monthly View)

MonthFeeding Focus
February– Add compost or aged manure to garden beds- Start seeds indoors (use seed-starting mix, no fertilizer yet)
March– Apply balanced fertilizer (10-10-10) 2 weeks before planting- Transplant early crops (greens, onions)- Light liquid feed (fish emulsion) 1 week after transplant
April– Direct sow more crops (carrots, radishes, peas)- Feed with compost tea or ½ strength fertilizer every 2–3 weeks
May– Transplant warm-season crops (tomatoes, peppers, squash)- Feed with higher nitrogen (e.g. 20-5-10) to promote leafy growth
June– Side-dress or liquid-feed with balanced or high P/K fertilizer (5-10-10)- Begin bloom/fruit support for tomatoes, squash, cucumbers
July– Feed every 2–3 weeks during fruiting with vegetable or tomato fertilizer– Apply compost tea or fish emulsion for sustained production
August– Continue fruiting crop feeding- Begin prepping soil for fall crops with compost- Plant fall greens/root crops in cooler zones
September– Feed fall crops (spinach, kale, beets) with nitrogen-rich organic fertilizer (blood meal, fish emulsion)- Avoid overfeeding late in the season
October– Final light feeding of fall crops- Add compost or mulch to protect soil going into winter
November– Plant cover crops (clover, vetch) or mulch heavily- No feeding needed unless in Zone 10–11 (where planting continues)
December– Rest month (or continued fall harvest in warmer zones)- Optional compost applications in mild climates

Fertilizer Frequency Summary

Leafy Crops: Feed lightly every 2–3 weeks during active growth.

Fruiting Crops: Feed every 2–3 weeks from bloom through harvest.

Root Crops: Feed only lightly at planting and mid-season.