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Growing Herbs in Mason Jars

Mason jars make charming, space-efficient containers for growing fresh herbs on your windowsill. While they present some unique challenges (no drainage holes!), with the right setup and care techniques, you can enjoy fresh basil, mint, cilantro, and more just steps from your kitchen. This guide covers everything you need for a successful mason jar herb garden.

Quick Reference

Best Jar Size

Wide-mouth quart (32 oz)

Herbs Per Jar

1 herb per quart jar

Sunlight Needed

6+ hours daily

First Harvest

3-4 weeks

Watering Frequency

Every 3-7 days

Difficulty Level

Beginner

Drainage

Layer system required

Lifespan

2-6 months per plant

Why Grow Herbs in Mason Jars?

Advantages

Repurpose jars: Free containers from your kitchen
Space efficient: Perfect for small windowsills
Visible roots: See root health and water levels
Attractive display: Great kitchen decor
Easy to move: Relocate for optimal light

Challenges to Address

No drainage: Requires layered drainage system
Limited space: Not for large or mature plants
Overwatering risk: Easy to add too much water
Root visibility: Algae can grow in clear glass
Heat absorption: Jars can heat up in sun

Mason Jar Setup and Requirements

Best Jar Sizes for Herbs

Pint (16 oz)

Good for: Chives, thyme starts, propagating cuttings

Plants will outgrow quickly

Quart (32 oz) - Best Choice

Good for: Most herbs - basil, mint, cilantro, parsley

Ideal balance of size and aesthetics

Half-Gallon (64 oz)

Good for: Large basil, mint, or multiple small herbs

More root space, longer plant life

Critical: The Drainage Layer System

Since you cannot drill drainage holes in glass, you must create a false-bottom drainage system:

Bottom

1-2"

Drainage Layer

Pebbles, gravel, or LECA (expanded clay balls). Creates space for excess water.

Middle

1/4"

Charcoal Layer

Activated charcoal absorbs impurities and prevents odors from stagnant water.

Optional

Thin

Mesh Separator

Window screen or landscape fabric keeps soil from mixing with drainage.

Top

Fill

Potting Mix

Lightweight, well-draining potting mix to 1 inch below rim.

Soil Mix Requirements

Ideal Potting Mix

Use a lightweight, fast-draining mix - critical since excess water can't escape easily:

50% quality potting mix
30% perlite for drainage
20% coco coir for moisture balance

Why Fast-Draining Matters

Water moves through quickly to drainage layer
Roots stay moist but not waterlogged
Reduces root rot risk in closed containers
Better aeration for healthy root growth

Best Herbs for Mason Jars

Excellent Choices

Basil: Thrives if harvested regularly, keeps compact
Mint: Very adaptable, any variety works
Cilantro: Best in cool conditions, quick to bolt
Parsley: Both flat-leaf and curly work well

Chives: Shallow roots, cut-and-come-again
Thyme: Compact, tolerates drier soil
Green Onions: Regrow from kitchen scraps!
Lemon Balm: Fragrant, easy to grow

Less Suitable

Rosemary: Needs deep roots, gets large - use larger containers
Sage: Becomes woody and large over time
Oregano: Spreading habit, needs more space
Dill: Tall growth, develops taproot

Step-by-Step Planting Guide

1Gather materials

You'll need wide-mouth quart mason jars, pebbles or LECA for drainage, activated charcoal, quality potting mix, and herb seedlings or seeds. Clean jars thoroughly if repurposed.

2Create drainage layer

Add 1-2 inches of pebbles or LECA to the bottom of each jar. This creates space for excess water to drain away from roots.

3Add charcoal layer

Sprinkle a thin layer (1/4 inch) of activated charcoal over the pebbles. This absorbs impurities and prevents the stagnant water smell that can develop without drainage holes.

4Add potting mix

Fill jar with lightweight potting mix to about 1 inch below the rim. Moisten the soil before planting - it should be damp but not soggy.

5Plant your herbs

Make a small hole and plant seedling at the same depth it was growing. For seeds, sprinkle on surface and cover lightly. One herb per quart jar.

6Position in sunlight

Place jars where they receive 6+ hours of sunlight. South-facing windows are ideal. Rotate jars weekly for even growth.

7Water carefully

Without drainage holes, overwatering is the biggest risk. Water sparingly - only when top inch of soil is dry. Use a spray bottle for gentle watering.

Watering Schedule

Critical: Less is More

Overwatering is the #1 killer of mason jar herbs. Without drainage holes, excess water has nowhere to go. Water sparingly and check soil before adding more.

Watering Guidelines

Check soil moisture by inserting finger 1 inch deep
Water only when top inch is completely dry
Use a spray bottle for gentle, controlled watering
Add small amounts - 2-4 tablespoons at a time
Check drainage layer - water shouldn't reach roots

Typical Frequency

Summer/Warm: Every 3-5 days
Winter/Cool: Every 5-7 days
Signs to water: Light-feeling jar, pale soil, slight wilt
Signs to wait: Heavy jar, dark moist soil, water visible in drainage layer

Tip: Pick up your jar - you'll learn to feel the difference between wet and dry by weight.

Expected Yield and Lifespan

3-4

Weeks to first harvest

2-6

Months productive lifespan

Weekly

Harvest frequency possible

Regular harvesting keeps herbs compact and extends productive life. Pinch from the top to encourage bushier growth.

Common Container-Specific Problems

Root Rot / Plant Death

Cause: Overwatering - roots sitting in water in drainage layer

Solution: Water less frequently, check drainage layer isn't full, use faster-draining soil mix

Mold on Soil Surface

Cause: Poor air circulation, overwatering, decaying organic matter

Solution: Improve airflow, reduce watering, scrape off mold, add more perlite to mix

Algae Growth on Glass

Cause: Light reaching wet areas through clear glass

Solution: Wrap jar in decorative paper or burlap, or use painted jars

Leggy, Stretched Growth

Cause: Insufficient light - herbs reaching toward light source

Solution: Move to brighter location, rotate jars weekly, consider grow lights

Yellowing Leaves

Cause: Overwatering, nutrient deficiency, or root problems

Solution: Let soil dry out, check roots, feed with diluted liquid fertilizer

Herbs Bolting (Flowering)

Cause: Heat stress, root-bound, or natural life cycle ending

Solution: Keep cool, harvest regularly, start new plants as backup

Frequently Asked Questions

Can herbs really grow in mason jars?

Yes, many herbs grow well in mason jars, especially compact varieties and herbs you harvest frequently. Wide-mouth quart jars work best, providing adequate soil volume for small root systems. The key challenges are drainage (mason jars have no holes) and limited space, but with proper setup and care, you can successfully grow basil, mint, cilantro, parsley, chives, and more.

How do you add drainage to a mason jar?

Since you can't drill glass safely, create a drainage layer instead: Add 1-2 inches of pebbles, gravel, or LECA (expanded clay balls) at the bottom. Add a thin layer of activated charcoal on top to prevent odors and mold. Then add your potting mix. This creates a reservoir that separates roots from standing water. Water carefully - less is more without true drainage holes.

What size mason jar is best for herbs?

Wide-mouth quart jars (32 oz) are ideal for most herbs, providing adequate soil depth and root space. Pint jars (16 oz) work for very small herbs like chives or thyme starts, but plants will need transplanting as they grow. Half-gallon jars (64 oz) work great for larger herbs like basil or mint. Avoid regular (narrow) mouth jars - wide mouth allows better planting and airflow.

Which herbs grow best in mason jars?

Best performers: Basil (harvest frequently to keep compact), Chives (shallow roots, cut-and-come-again), Cilantro (if kept cool), Mint (any variety, very adaptable), Parsley (both flat and curly), Thyme (compact, drought tolerant), Green onions (regrow from scraps). Avoid: Large rosemary, sage, or oregano plants - they need more root space.

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