Plant growers often use the terms greenhouse and hothouse interchangeably, because both greenhouses and hothouses take advantage of sunlight and heat to provide the plants need to thrive.
However, the greenhouse generates warmth through sun rays. And hothouses, on the other hand, are heated with artificial sources to produce the warmth your plants need to grow healthy.
In most instances, a greenhouse can be a hothouse. Adding a source of supplemental heat into the greenhouse structure will transform it into a hothouse.
The concept implies that you can use your structure as a greenhouse and generate heat from the sun in spring and summer.
And by adding supplemental heat into the greenhouse structure as the fall and winter come will create a cozy and relaxing hothouse your plants can enjoy.
Let’s Clear Up the Confusion Between Greenhouse and Hothouse
Dual Purpose Structure
In reality, a greenhouse and hothouse need not be a separate structure.
As first stated above, the key difference between the two is as such: you can use the structure as a greenhouse in spring and summer by taking advantage of the sun rays to provide heat to your plants. And in winter, add supplemental heat and turn the structure into a hothouse.
All in all, plants require the warmth they need to grow healthy while inside these structures. And it does not matter whether you call it a greenhouse or a hothouse.
Are You Considering Year-Round or Seasonal Planting?
Choosing the best one for you depends on what purpose you have in mind.
If you want to start seedlings in the late spring and grow annuals in summer, shield crops from excessive heat of the sun, or protect plants from harmful pests, a greenhouse is ideal to make it a success.
But if you’re considering using the structure year-round, you might consider supplemental heating, making the hothouse the best alternative in winter.
Also Consider The Climate
Climate is another factor you have to consider when designing a greenhouse structure. In warmer regions with a mild winter, a greenhouse is enough to protect your plants from the cold weather.
However, in regions where temperatures drop below freezing each winter, consider a supplemental heat to maintain the temperatures your plants require to thrive. This will also prevent the possibility of extreme cold injury in the fall and winter.
Plants To Grow
The success of growing plants and vegetables in the greenhouse depends on the situation and the specific plants themselves.
Roots and leafy vegetables can thrive inside an unheated greenhouse and do not easily get damaged by freezing weather.
But if you are considering growing tropical annual vegetables like cucumbers (Cucumis sativus) and summer squash (Cucurbita pepo) in winter, a heated hothouse will make your harvest a success.
Most commercial greenhouses and hothouses today use innovative production facilities for growing vegetables, flowers, and fruits.
These modern structures leverage the benefits of high-tech equipment such as screening installations, heating, cooling, and lighting fixtures.
And these innovative equipments are programmable. Greenhouse temperatures through heaters and windows are controlled by computers to optimize the plant’s growing conditions.
Plant growers use different techniques to achieve optimum comfort and benefit the greenhouse or hothouse can provide to the plants.
However, a modern strategy of evaluating the temperature, humidity, and ventilation is constant to ensure cultivating a specific crop inside the growing facility is a success.
How The Greenhouse Works?
The Concept of the Greenhouse
The concept of greenhouses is to generate warmer temperatures inside the structure. The solar radiation passes through the transparent roof and walls and heats the ground inside.
It also warms up the air, providing the heat your plants need while growing within the greenhouse.
Ventilation is essential to regulate the air movement and the optimum level of humidity inside the facility. The plants growing inside the greenhouse structure are susceptible to various problems when suffering from lack of ventilation.
Providing adequate ventilation will prevent the likelihood of pathogen build-up in the plants that thrive in a still air condition.
Moreover, it ensures a constant supply of fresh air for photosynthesis and plant respiration. It also helps pollinators to access the crops within the greenhouse.
Modern greenhouses feature programmable vents and fans via computers to control and achieve the ideal temperature inside the greenhouse.
Glazing is the covering around the greenhouse frame, mostly made of glass material responsible for sunlight rays to pass through the structure.
However, some gardeners prefer plastic sheets as they work well too, and are less expensive than glass materials.
Polycarbonate is another type of material typically used as greenhouse glazing. It is sturdy and can transmit heat well on flat or bent surfaces. Plus, it is lightweight and can keep heat better than glass or plastic.
In warmer regions, when the intense sun hits directly to the greenhouse structure, adding a shading cover will keep plants from getting burned.
It helps reduce the amount of heat inside the greenhouse. And materials like shade cloth and roll-up screens provide shade while controlling the heat temperature within the greenhouse.
The plants growing inside the greenhouse facility are safe from pests and bacterial infection when cleanliness is maintained. Keeping your gardening tools clean and sanitized before entering the greenhouse is essential. It will help ensure the crops you are growing within the structure are safe from pests and diseases.
How To Heat a Greenhouse for Free in Mild Winter Regions
If your growing facility is small yet wants year-round gardening, there are a lot of easy free options for greenhouse heating.
Leverage the Power of Solar Energy
Positioning your greenhouse to harness the sun’s power and receive direct sunlight exposure is the best way to capture solar energy.
As the sun rays cross the sky, the structure should be oriented to face the south, particularly in the northern hemisphere where the winter sun is in the southern part of the sky.
And by taking advantage of the solar energy to capture the abundance of daytime, it releases the accumulated heat to boost the colder temperature at night.
When your greenhouse receives plenty of sunlight, adding some thermal mass inside your structure will help hold on to the heat you’ve gathered through the solar power.
Thermal mass or heat sink absorbs heat a few degrees in the day via conduction. It helps prevent rapid temperature drop by slowly releasing the heat at night. And these are objects that can absorb energy from the sun with a certain amount of heat.
Some gardeners use 55-gallon drums of water or build the north wall with insulating materials like cinder blocks to absorb warmth from the hot air in the greenhouse during the day and gradually release the heat at night.
And large volumes of water, stone, cement, and some other materials are proven to minimize heat loss at night.
Insulate Greenhouse with Bubble Wrap
After absorbing the heat from sunlight through thermal mass, make sure you’re not losing the heat through air leaks.
Controlling the airflow inside the structure is essential when the air is circulating. You don’t want to let the warmth leak out and create cold spots inside the greenhouse.
Using bubble wrap will help insulate glass walls to prevent air leaks and double up against plastic sheeting inside the greenhouse. The air in the bubble has an excellent insulating quality.
Also, adding some row covers of horticultural fleece over the plants is another approach you can take advantage of to insulate your greenhouse.
How Does The Hothouse Work?
The purpose of both greenhouses and hothouses is to trap the heat within the growing facility and keep the circulating air warmer. The hothouse method helps plants thrive, extending the growing season even in winter months.
A hothouse is beneficial in regions with colder climates as it helps gardeners produce fruits and vegetables year-round.
In summer and spring, heating greenhouse through direct sun rays is sufficient to help the plants thrive. However, supplemental heat is essential during the winter months to extend the gardening season.
Again, when you add supplemental heating, that is when you are moving from a greenhouse to a hothouse.
Low-Cost Hothouse Heaters
Heating a hothouse through electricity can cost you a significant amount, especially in regions with colder climates. It is likely the simplest option when it comes to heating the house.
But losing heat during the process of heating is the primary problem of gardeners due to poor insulation.
Greenhouse coverings allow the heat of sunlight to pass through the frame structure in the spring and summer. But it likewise releases the heat generated inside during the heating operation in winter.
So thinking of a few options and taking advantage of all the sustainable ways to keep the air warm inside the greenhouse will help you grow plants continuously year-round without spending an ample amount.
The passive heating methods used to seek heat using low energy input help minimize the operating cost.
The Paraffin heater is one of the least expensive mobile options to heat your hothouse in winter. If the heating demand is not too high, using the paraffin heater makes an efficient way to keep the structure frost-free.
It is sufficient enough to generate heat within the structure when the outside temperature does not fall below -6°C and the inside temperatures require about only 5°C.
Besides, it helps put heating costs down and helps plants grow in colder months as it traps heat within the structure up to a maximum length of 8ft in winter.
Livestock Waste Heat
Waste heat from livestock is also another low-input element you can use to heat your hothouse in winter. Some gardeners place chicken coop inside a greenhouse to utilize the heat generated by the chickens, while other gardeners rely on geothermal heating.
Heating With Compost
Heating a greenhouse with compost for large-scale greenhouses uses sophisticated equipment, such as water pipes, to help circulate heat around the gigantic structure.
But for a home gardener, heating a greenhouse with compost using existing compost bins to warm specific areas is relatively a simple process.
Gardeners can also implement trench composting and create staggered row planting while keeping the heat through the winter.
Some use small wood stoves to heat a hothouse in winter. This can be a sustainable and cheap way to add occasional heat to your hothouse, particularly if you have access to firewood during winter.
However, if you live in regions with extreme cold in winter, heating the hothouse with firewood can be extensively laborious.
Aside from hauling the firewood, you have to tend the fire to keep it burning and ensure the chimney is insulated and passes through the structure of your hothouse.
Other gardeners also use a propane heater inside the greenhouse to generate heat. However, make sure you know how to use it when considering a propane heater. Also, an adequate supply of oxygen is essential for the gas to burn and keep the structure heated.
Small Greenhouse Cold Frame
You can turn the smallest type of greenhouse into a cold frame to protect your delicate plants. A plastic sheeting or glass windows resting on the top of the garden bed can make a simple set up to help protect your plants from cold winter.
And if you love DIY projects, you can construct the frame where you can lift the roof cover when the sun gets too warm.
Final Thoughts on Greenhouse vs. Hothouse
Growing specific crops year-round inside your greenhouse means that you will need heat in the colder months of the year.
However, if you live in most temperature regions, you might likely need simple adjustments and customize your setup to ensure growth even in colder days.
For those extra cold nights in regions with extreme weather, protecting delicate plants from freezing is not that hard. All you need is to take advantage of the heat from the sun, and in extreme weather, add supplemental warmth for your plant to survive and thrive.
Moreover, using passive energy like solar energy and compost piles to cut the costs of heating is sufficient to keep the greenhouse warm in regions with a mild winter.
Also, there are less expensive heaters you can use to ensure the air circulating inside the greenhouse is warm enough for your plants, while the outside temperature drops below to a freezing point.
The problem of air circulation inside the greenhouse will encourage the growth of molds and mildew, making it essential to release the moisture from foliage.
In spring and summer, controlling air circulation inside the greenhouse can be resolved by opening vents in the roof.
However, in winter months, everything is closed up tight to keep the warmth inside.
But some gardeners use an electric heater with a fan. This is an excellent way to keep the air circulating inside, even in the cold winter days. This provides steady airflow within the greenhouse and helps maintain the desired temperature.
When considering growing plants year-round inside the greenhouse, make sure the source of heat you will use on winter days is safe.
Remember to use thermal systems that will give you peace of mind while growing plants in winter. Do you have experience adding supplemental heat to your greenhouse in the winter? Share your thoughts below.