Heated Greenhouse vs Indoor Grow Lights: Winter Growing Costs and Results

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If you want fresh food or active plant growth through winter, you have two main routes: heat your greenhouse, or bring growing indoors under grow lights. Both work. They cost different amounts, grow different things well, and fail in different ways. This comparison helps you pick the right route, or the right mix of both.

The Core Difference

A heated greenhouse buys warmth but relies on the sun for light. In the darkest part of winter, natural light is weak and short, so even a warm greenhouse grows slowly. An indoor grow-light setup buys light but relies on your house for warmth. You control day length completely, but space is limited and all light comes from electricity.

Cost Tiers

We do not quote prices because energy rates and equipment costs vary widely by region and year. Instead, here is how to estimate your own cost and how the options compare in tier.

The pattern most growers find: heating costs rise steeply as you raise the target temperature and as outdoor temperatures fall, while grow-light costs are predictable and fixed by wattage and hours. For small volumes of greens and seedlings, lights indoors are usually cheaper to run than heating a whole greenhouse to growing temperature.

What Each Grows Best

Results and Reliability

A heated greenhouse gives you room: whole plants, fruit trees, big overwintering collections. But in the Persephone period, when day length drops below about ten hours, heat alone does not produce much growth. Many growers find the best winter greenhouse strategy is to hold plants cool and grow mainly cold-hardy greens, rather than heating for active growth. Our Winter Lettuce & Greens in a Greenhouse guide covers that approach.

Indoor lights give fast, predictable growth in a small space, and a power cut affects them less because your house stays warmer longer than a greenhouse. On the other hand, space is tight, and plants must eventually move out for hardening off. For the greenhouse side, a solid Greenhouse Winter Power Outage Plan is essential.

The Hybrid Approach

Most experienced growers do not choose one or the other. A common winter setup:

• Keep the greenhouse frost-free or cool for overwintering plants and cold-hardy greens.
• Run a small indoor light setup for microgreens, baby greens, and late-winter seed starting.
• Move seedlings into the greenhouse as days lengthen and temperatures rise.

This keeps heating costs low while still giving you fresh food and a head start on spring. For indoor enclosures, see our Best Indoor Greenhouse Cabinets guide.

Ways to Cut Winter Costs Either Way

In the greenhouse

• Lower the target temperature. Frost-free instead of warm is the biggest single saving.
• Insulate. Horticultural bubble wrap on north walls and ends reduces heat loss where light matters less.
• Heat a smaller space. Partition off one section with plastic sheeting and heat only that.
• Seal drafts around doors, vents, and panel gaps.
• Use a good thermostat placed at plant height, not near the heater.

Under lights indoors

• Use efficient LED fixtures rather than older fluorescent or incandescent lighting.
• Keep lights at the right height so light reaches plants instead of spilling into the room.
• Use reflective surfaces or an enclosure to keep light on the plants.
• Match hours to the crop rather than running lights longer than needed.

Measure before and after any change with a plug-in energy monitor. Real numbers from your own setup beat any general estimate.

Verdict

Choose a heated greenhouse if you need space for large plants, overwintering collections, or potted fruit. Choose indoor grow lights if you want the most food and seedlings per unit of energy in a small space. For most hobby growers, a frost-free greenhouse plus a modest indoor light shelf is the most cost-effective winter plan.