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December Gardening Guide

Winter | Indoor Growing & Planning Season

December brings the gardening year full circle. While outdoor gardens rest under frost and snow in most regions, indoor growing thrives and planning for the new year begins. It's a month for microgreens on the windowsill, seed catalogs by the fire, and dreams of spring gardens to come. The thoughtful gardener uses this quiet season to prepare for even greater success in the year ahead.

December Tasks by Zone

Zones 3-5

Cold

Plant

  • Indoor microgreens
  • Sprouts
  • Indoor herbs under lights

Harvest

  • Indoor herbs
  • Microgreens
  • Sprouts
  • Stored vegetables

Key Maintenance

  • Indoor growing
  • Garden planning
  • Seed ordering
  • Tool care

Deep winter! Focus entirely on indoor growing and planning. Read seed catalogs by the fire. Dream of spring gardens. Order seeds before varieties sell out.

Zones 6-7

Moderate

Plant

  • Indoor growing
  • Cold frame greens (with protection)
  • Garlic (early month, Zone 7)

Harvest

  • Cold frame greens
  • Indoor herbs
  • Microgreens
  • Storage vegetables

Key Maintenance

  • Indoor growing
  • Cold frame management
  • Planning
  • Protection

Limited outdoor opportunity under heavy protection. Focus shifts to indoor growing and next year's planning. Cold frames may still produce with vigilant care.

Zones 8-9

Mild

Plant

  • Garlic (early month)
  • Cool-season vegetables
  • Winter greens

Harvest

  • Cool-season crops
  • Winter greens
  • Herbs

Key Maintenance

  • Active cool-season garden
  • Some frost protection
  • Planning for spring

Active gardening continues! Cool-season crops thrive in mild winter weather. Some frost protection needed. Begin planning spring warm-season garden.

Zones 10-11

Warm

Plant

  • Cool-season vegetables
  • Garlic
  • Winter crops
  • Herbs

Harvest

  • Full cool-season production
  • Herbs
  • Root vegetables

Key Maintenance

  • Prime growing season
  • Succession planting
  • Garden expansion

Your best growing season! Cool-season crops produce abundantly. Plant continuously for extended harvest. Plan for spring/summer transition.

December Tasks & Activities

Indoor Growing

  • Maintain microgreens production (new tray weekly)
  • Grow sprouts for quick nutrition
  • Care for windowsill herbs
  • Monitor grow light timers (14-16 hours)
  • Force bulbs for holiday blooms
  • Start mushroom kits
  • Grow lettuce and greens under lights

Planning & Dreaming

  • Review this year's garden journal
  • Browse seed catalogs and websites
  • Design next year's container layout
  • Calculate seed and supply needs
  • Research new varieties to try
  • Plan crop rotation and successions
  • Set gardening goals for next year

Plant Care

  • Reduce watering frequency for dormant plants
  • Increase humidity around houseplants
  • Check for indoor plant pests
  • Keep plants away from cold windows
  • Avoid fertilizing dormant plants
  • Rotate plants for even light exposure
  • Monitor cold frame and protected plants

Equipment & Supplies

  • Order seeds before popular varieties sell out
  • Research and purchase grow lights
  • Organize seed storage
  • Plan container purchases for spring
  • Order season extension supplies
  • Inventory and replace worn tools
  • Gift gardening supplies to friends

December Garden Projects & Gifts

Microgreens Gift Garden

Beginner

Create a microgreens growing kit as a holiday gift - includes everything needed for fresh winter greens.

Supplies Needed:

  • Shallow tray with drainage
  • Seed starting mix
  • Assorted microgreen seeds
  • Spray bottle
  • Instructions card

Tips:

  • Include easy varieties: sunflower, radish, pea shoots
  • Package seeds in labeled envelopes
  • Add care instructions for recipient
  • Include a card explaining microgreens
  • Perfect gift for food-loving friends

Amaryllis Forcing

Beginner

Force amaryllis bulbs for stunning holiday and winter blooms.

Supplies Needed:

  • Amaryllis bulbs
  • 6-8 inch pot with drainage
  • Potting mix
  • Decorative container (optional)

Tips:

  • Plant with 1/3 of bulb above soil
  • Water sparingly until growth appears
  • Blooms appear in 6-8 weeks from planting
  • Stake tall stems to prevent toppling
  • Save bulb for reblooming next year

Herb Garden Starter Kit

Beginner

Assemble a complete herb garden kit for gift-giving.

Supplies Needed:

  • Small pots (3-4 inches)
  • Quality potting mix
  • Herb seeds or small transplants
  • Plant labels
  • Care guide

Tips:

  • Include easy herbs: basil, parsley, chives
  • Add a south-facing window tip card
  • Consider including grow light recommendation
  • Package in attractive basket or box
  • Great gift for cooking enthusiasts

Indoor Seed Starting Setup

Intermediate

Set up your seed starting station in December to be ready for spring.

Supplies Needed:

  • Wire shelving or seed starting rack
  • T5 or LED grow lights
  • Timer
  • Seed trays and inserts
  • Heat mat

Tips:

  • Position in basement or spare room
  • Lights should be 2-4 inches above plants
  • Set timer for 14-16 hours daily
  • Heat mat speeds germination significantly
  • Test system now with quick-growing lettuce

December Pest Watch (Indoor)

Indoor pests become the main concern in December. Heated, dry homes create stress that makes plants vulnerable. Regular monitoring keeps problems from escalating.

Indoor Aphids

Windowsill herbs, houseplants

Signs:

Clusters on new growth, sticky residue, yellowing leaves

Prevention:

Quarantine new plants, inspect regularly, maintain plant health

Treatment:

Spray off with water, insecticidal soap, neem oil

Spider Mites

Indoor plants, especially in dry heated rooms

Signs:

Stippled leaves, fine webbing, bronzed appearance

Prevention:

Increase humidity, mist regularly, avoid dry conditions

Treatment:

Spray with water, insecticidal soap, increase humidity

Fungus Gnats

Indoor plants, especially overwatered ones

Signs:

Tiny black flies near soil, larvae in moist soil

Prevention:

Let soil dry between waterings, use yellow sticky traps

Treatment:

Bti (Mosquito Bits), hydrogen peroxide drench, beneficial nematodes

Scale Insects

Indoor plants, especially woody herbs

Signs:

Brown bumps on stems, sticky honeydew, yellowing

Prevention:

Inspect plants regularly, quarantine new plants

Treatment:

Remove manually with alcohol swab, horticultural oil

Tips for December Success

Review and Reflect

December's quiet is perfect for reviewing this year's garden. What varieties thrived? What failed? Which pests were problematic? Document everything while memories are fresh. These notes shape next year's better garden.

Dream and Design

Sketch next year's container layout. Consider traffic flow, sun exposure, and aesthetics. Plan which containers need replacing. Design new features: trellises, vertical gardens, or drip irrigation. The dream season makes spring reality easier.

Order Seeds Early

Popular varieties sell out fast! Place seed orders by late January. Compare catalog prices and offerings. Try one new variety of each crop you grow. Read reviews and select disease-resistant options for problem areas.

Embrace Indoor Growing

December proves you can garden year-round. Microgreens, sprouts, and herbs provide fresh produce. Grow lights open possibilities. Forced bulbs add beauty. Indoor gardening fills the garden void and hones skills for spring.

Frequently Asked Questions

What can I grow indoors in December?
December is perfect for indoor growing! Microgreens harvest in 7-14 days. Sprouts in 3-5 days. Windowsill herbs (parsley, chives, mint, thyme) provide fresh flavor. With grow lights, grow lettuce, spinach, and greens. Force bulbs (amaryllis, paperwhites) for holiday blooms. Even mushrooms can be grown indoors with kits.
How do I care for houseplants in December?
Reduce watering as most plants slow growth in low winter light. Increase humidity with pebble trays or humidifiers - heated homes are very dry. Keep plants away from cold windows and heating vents. Hold off on fertilizing until spring. Group plants together to create humidity. Consider grow lights to supplement short days.
When should I start planning next year's garden?
December is ideal! While memories of this year are fresh, review your notes. What worked? What failed? Order seed catalogs now - they make perfect holiday reading. Design your garden layout. Calculate how many containers you need. Order seeds in January before popular varieties sell out.
Is it too late to plant garlic in December?
In zones 8-10, December garlic planting is still possible if ground isn't frozen. In colder zones, it's too late - the ground is frozen. If you missed fall planting, buy 'spring garlic' (elephant garlic or softneck varieties) to plant in early spring, though heads will be smaller than fall-planted garlic.
How do I keep herbs alive indoors through winter?
Position herbs in your brightest window (south-facing ideal). Consider supplemental grow lights - many herbs need 6+ hours of light. Let soil dry slightly between waterings. Maintain humidity (herbs dislike dry heated air). Harvest regularly to encourage bushy growth. Accept that some herbs (basil especially) may struggle - start fresh from seed in spring.
What gardening gifts can I give?
Great garden gifts include: seed starting kits, grow lights, quality hand tools, seed gift certificates, gardening books, self-watering containers, mushroom growing kits, microgreens supplies, seed catalogs, and gift cards to local nurseries. Amaryllis or paperwhite bulb kits make wonderful last-minute gifts that bloom in weeks.
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