Guide to Grow Lights: Bringing Summer Sunshine Indoors

Dutch winters bring as little as 5 hours of weak daylight in December and January. For anyone trying to grow edible vegetables indoors, that’s nowhere near enough. Most vegetables need 10-16 hours of good light per day to produce a worthwhile harvest.

Grow lights bridge that gap. They’ve become dramatically cheaper and more efficient in recent years, making indoor winter growing accessible to anyone with a windowsill, a shelf, or a spare corner. This guide covers which vegetables benefit most, what kind of light to buy, and how to set up a simple system without breaking the bank.

Why Light Matters More Than You Think

Plants use light as their energy source through photosynthesis. When light drops below a certain threshold, plants don’t just grow slowly — they stop producing altogether. Leaves become pale and thin, stems stretch and weaken, and fruiting vegetables won’t set fruit at all.

The Dutch winter creates a triple problem:

Short days — only 7-8 hours in December
Low sun angle — light passes through more atmosphere, losing intensity
Cloud cover — the Netherlands averages 70-80% cloud cover in winter

Even a south-facing window in January delivers roughly a quarter of what the same spot gets in June. For many vegetables, that simply isn’t enough.

Which Vegetables Benefit Most from Grow Lights?

Not every plant needs the same amount of light. Here’s a practical breakdown ranked by how much they gain from supplemental lighting.

High Benefit: Fruiting Vegetables (14-16 hours of light)

These need the most light because they must power both leaf growth and fruit production:

Tomatoes (cherry varieties) — Compact cherry tomatoes like Tiny Tim or Micro Tom are bred for indoor growing. They need strong, consistent light but reward you with sweet fruit all winter.
Hot peppers — Surprisingly well suited to indoor growing. Compact varieties produce steadily under lights. They tolerate dry indoor air better than most vegetables.
Strawberries (day-neutral varieties) — Day-neutral types like Albion or Mara des Bois keep fruiting regardless of season when given enough light.
Cucumbers (mini varieties) — Compact types like Picolino produce small cucumbers indoors if light is strong enough.

Very High Benefit: Fast-Growing Greens (12-14 hours of light)

These grow quickly and visibly respond to more light with faster, denser growth:

Lettuce — All types grow well under lights. Loose-leaf varieties are fastest: from seed to salad in 4-5 weeks.
Spinach — Loves cooler indoor temperatures and responds strongly to consistent light. Perfect for a windowsill with supplemental LEDs.
Arugula (rucola) — One of the fastest crops, ready in 3-4 weeks. Grows leggy and bitter without enough light; under lights it stays compact and peppery.
Pak choi — Fast, productive, and delicious. Grows beautifully under LEDs with minimal fuss.
Mustard greens — Spicy, quick, and attractive. Ready in 3-4 weeks under lights.

Good Benefit: Herbs (10-14 hours of light)

Herbs are the classic indoor crop and respond well to supplemental light:

Basil — The difference is dramatic. Under grow lights, basil stays bushy and productive. Without, it becomes leggy and weak within weeks.
Cilantro — Bolts quickly in summer heat but grows perfectly in a cool indoor spot with steady light.
Dill — Fast-growing, light-hungry. Much better results under lights than on a dim windowsill.
Parsley — More tolerant of lower light than basil, but still noticeably better with supplemental lighting.

Moderate Benefit: Root Vegetables and Cool-Season Crops (10-12 hours of light)

These tolerate lower light but still grow faster and stronger with some help:

Radishes — Surprisingly easy indoors. 25-30 days from seed to harvest. Need at least 15 cm deep containers.
Green onions / spring onions — Regrow from kitchen scraps or grow from seed. Low light tolerance, but better flavor and faster growth with lights.
Microgreens and sprouts — The ultimate beginner crop. Sunflower, pea shoots, radish, and broccoli microgreens are ready in 7-14 days and need only moderate light.
Beet greens — Grow beets for their tops rather than roots indoors. Colorful, nutritious, and productive under lights.

Understanding Grow Light Types

Full-Spectrum LED (Recommended)

This is what you want. Modern full-spectrum LEDs:

Produce the wavelengths plants actually use
Run cool, so they can sit close to plants
Use very little electricity (10-40W for a home setup)
Last 25,000-50,000 hours
Emit white light that looks pleasant in your home

Avoid the older purple/pink “blurple” LEDs. They work, but the light is unpleasant to live with and newer white LEDs perform just as well.

Fluorescent T5 Tubes

Still a decent budget option:

Lower upfront cost
Good for leafy greens and herbs
Less efficient than LED (higher electricity cost over time)
Need replacing every 1-2 years

What NOT to Buy

Incandescent bulbs — produce heat, not useful light
Cheap clip-on “grow lamps” with tiny LEDs — too weak for anything beyond a single small herb pot
Halogen lights — too hot, inefficient, fire risk

Simple, Affordable Setups for Home

Setup 1: The Windowsill Booster (Under 30 EUR)

Best for: herbs, small greens, microgreens

What you need:

1 LED light bar or strip (20-30W), full spectrum
A mechanical timer (or smart plug)
Your existing windowsill and pots

How it works: Mount the LED bar above your windowsill plants using adhesive hooks or a simple shelf bracket. Set the timer so the light runs from 6:00 to 22:00 (16 hours). Your plants get natural daylight plus supplemental LED light, combining for excellent growing conditions.

Cost: LED bar 15-25 EUR + timer 5 EUR

Setup 2: The Shelf Garden (50-80 EUR)

Best for: lettuce, spinach, herbs, radishes, microgreens

What you need:

A simple metal shelf rack (IKEA HYLLIS or similar, ~15 EUR)
2-3 LED light bars or a shop-light style LED fixture per shelf
Timer
Drip trays for each shelf

How it works: Each shelf becomes its own growing level. Mount lights under the shelf above so they shine down on the plants below. You can grow different crops on each level. The top shelf gets ambient room light; lower shelves rely entirely on LEDs.

Cost: Shelf 15 EUR + LEDs 30-50 EUR + timer 5 EUR + trays 10 EUR

Setup 3: The Dedicated Growing Station (80-120 EUR)

Best for: tomatoes, peppers, strawberries, and larger crops

What you need:

A small growing tent or dedicated corner with reflective backing (even aluminum foil works)
A 100-150W LED panel or multiple bar lights
Adjustable hanging system (chains or rope ratchets)
Timer
Small fan for air circulation

How it works: The reflective walls bounce light back onto plants from all angles, dramatically increasing efficiency. The stronger light supports fruiting crops that need more energy. The fan strengthens stems and prevents mold.

Cost: LED panel 50-80 EUR + reflective material 10 EUR + fan 10 EUR + hangers 10 EUR + timer 5 EUR

Key Settings: Getting the Most from Your Lights

Light Height

Seedlings and microgreens: 10-15 cm above plants
Leafy greens and herbs: 15-25 cm above plants
Fruiting vegetables: 20-40 cm above plants

If leaves start curling or bleaching, raise the light. If stems are stretching toward the light, lower it.

Light Duration

Leafy greens and herbs: 12-14 hours per day
Fruiting vegetables: 14-16 hours per day
Microgreens: 12-16 hours per day

Always give plants at least 8 hours of darkness. Plants need dark periods for important metabolic processes.

Timing

Use a timer. Consistency matters more than perfection. A simple mechanical timer costs under 5 EUR and removes the hassle of remembering to switch lights on and off.

A practical schedule: lights on at 6:00, off at 20:00-22:00. This extends the natural daylight with morning and evening supplemental light.

Practical Tips for Success

Start small. A single shelf with lettuce and herbs teaches you more than an ambitious multi-tier setup that overwhelms you. Scale up once you have a feel for watering, light distance, and harvesting rhythms.

Combine with a window. Grow lights work best as a supplement to natural light, not a complete replacement. A shelf near an east or south window plus LED bars gives excellent results with lower electricity use.

Watch your electricity costs. A 30W LED running 14 hours a day uses about 0.42 kWh per day. At Dutch electricity prices (~0.30 EUR/kWh), that’s roughly 0.13 EUR per day or about 4 EUR per month. Very affordable. A 150W panel costs about 20 EUR per month — still reasonable for the harvest you get.

Keep it clean. Dust on LED panels reduces light output significantly. Wipe them down monthly.

Rotate crops. Grow lettuce for 5 weeks, harvest, replant immediately. With a shelf system you can stagger sowings so you always have something ready to pick.

Ventilation matters. Stagnant air invites mold and weakens stems. A small USB fan pointed at your plants makes a big difference, especially in enclosed shelf setups.

A Realistic Winter Growing Calendar

October-November

Set up your lights and start cool-season crops: lettuce, spinach, arugula, radishes. Start herb pots. Sow microgreens for quick first harvests.

December-January

Peak grow-light season. Natural light is at its lowest. Rely heavily on LEDs. Keep harvesting greens and resowing. Start pepper and tomato seeds in January for spring harvests.

February-March

Days are getting longer. Your lights supplement the increasing natural light. Tomato and pepper seedlings grow quickly now. Continue succession planting of greens.

April-May

Transition outdoor. Harden off indoor-started plants for the garden or balcony. Your grow lights have given you a 2-3 month head start on the season.

What to Expect: Realistic Harvests

With a simple two-shelf setup and 40-60W of LED lighting, you can realistically produce:

Lettuce: A salad bowl every 5-7 days from continuous harvesting
Herbs: Daily harvests of basil, cilantro, parsley
Microgreens: A tray every 10-14 days
Radishes: A handful every 4 weeks
Spinach: Regular pickings from a few pots

You won’t replace the supermarket entirely, but you’ll have the freshest possible greens and herbs at your fingertips — and the satisfaction of growing them yourself in the middle of a Dutch winter.

Getting Started This Week

Choose one crop — lettuce or basil are the easiest first choices
Buy an LED bar — a 20-30W full-spectrum bar from a garden center or online
Set up a timer — 14 hours on, 10 hours off
Sow seeds in a pot on your windowsill or shelf
Wait 3-5 weeks — your first indoor winter harvest is on its way

The best time to start was last autumn. The second best time is today.

Looking for fresh-picked produce when the season returns? Find a u-pick farm near you: