What is a 4-season greenhouse?

What is a 4-season greenhouse?

Every greenhouse offers some level of protection for your plants – protection from the wind, the weather, the cold. Greenhouses help you start seedlings earlier in the year than you might otherwise be able to outdoors, by providing warmer air and soil temperatures during the critical germination stage – perhaps in early Spring when you’re preparing for Summer. They also protect plants longer at the end of the growing season, again by holding that extra bit of warmth, a few degrees above the  cooling Autumn weather outside.

If you add some artificial heat to your greenhouse, then you can extend the season a little further, keeping the frosts away. Not many greenhouse heaters can raise the temperature much, though. A regular greenhouse is just too big, and too bad at keeping the heat in. Most seeds need at least 15 degrees C to germinate, and once germinated, the plants won’t grow much, if at all, below 10 degrees or so. You’re going to have to put a lot of electricity into an 8′ by 10′ glass greenhouse to keep plants going when it’s freezing outside.

Here’s where our greenhouses are different. They are small – which means they are much easier to heat. They are better insulated – featuring twinwall polycarbonate panels which hold the heat better than glass.

Adding heating to our regular self-watering greenhouses gives you a 3-season greenhouse. It’s mains powered, and only uses a fraction of what it would take to heat a regular greenhouse. Low voltage, safe, waterproof self-regulating heater cables run through the shelves, to warm the plants above. The heaters are thermostatically controlled via the smart control unit. Manage and monitor the temperature using the Harvst app.

“A genuinely warm environment, perfect for germinating seeds at any time of year, and for accelerating growth during colder periods.”
…in all Sprout 3-season mini greenhouses

Here’s a screenshot provided by one of our customers (on our forums) showing how the air temperature in their Sprout 14 mini greenhouse is nearly 7C while their unheated wooden greenhouse is pretty much frozen.

The air space in the Sprout 3-season and 4-season greenhouses can be kept-frost free when outside temperatures plummet well below zero, but it’s the soil temperature that’s really significant.

Because the shelves in the Harvst greenhouses are heated, the soil in the trays, tubs and pots resting on them can happily stay more than 10C above ambient, all through winter.

We all know that plants don’t just need a warm, cosy space. They also need sun – or more scientifically, the right spectrum and hours of light. As the sun gets lower in the sky, and the days get shorter, the plants know it. Many go to sleep – hibernate – and don’t grow at all. There are some hardy winter greens which work through the colder months, but generally your choice is limited.

Here’s where the 4-season greenhouses shine (excuse the pun…). As well as heating, our mini greenhouses are fitted with LED grow lights, which provide lots of extra light for the photosynthesis the plants need to grow. Now, with a warm space, and a full day of (artificial) light, you can grow all year round.

Don’t grow lights use buckets of electricity, you might ask. Yes, traditionally, they have done, but with “new LED technology” – an overused phrase if ever there was one – you get a remarkable about of Lux (light) for not a lot of Watts (electricity). A full rig of lights in a 4-season mini greenhouse uses less than 100 Watts.

Do they actually work? Or is this just another hobby grow-the-odd-leaf-of-lettuce system? Absolutely yes. It works. All the greens in our greenhouse photos have been grown indoors, in a dark and unheated workshop, in standard spec Sprout mini greenhouses.

“Does it work? Yes. All the greens in our website photos have been grown indoors in a dark, cool workshop with standard spec Sprout mini greenhouses.”

Our LED grow lights are low voltage, safe and waterproof – perfect for using in an irrigated, damp environment. They also give off a fair bit of warmth while they are on, and because they are mounted in the shelves, that warmth directly contributes to the warmth in the soil or growing medimu on the shelf above.

Harvst 4-season greenhouses let you grow continuously, all year round – but also let you start most summer seedlings very early in the year, and gradually train them up by varying the temperature as spring approaches, so you can start outside (or transplant into a regular greenhouse or polytunnel) and get a great headstart on the season.

The 3-season and 4-season mini greenhouses are not just to help you grow more in autumn, winter and spring – they are also designed to help you in the summer.

With an automatic self opening roof to vent lots of heat, twinwall polycarbonate panels to shield plants from direct sun and overheating, as well as automatic sensor-driven self watering, they are a great addition to any growers arsenal, whatever your space and whatever you’re growing.