There’s no one right way to run a greenhouse. With so many accessories, sizes, shapes, and even plants you can cultivate within, these all join powers with an almost endless combination of methods, mediums, and tools to use to start your greenhouse operation right – and to make sure it continues to run smoothly. Even the materials that go into your construction can vary widely, and must be chosen wisely.
Throw in where you build your greenhouse, however, and you add a whole other layer to your management. We’re not talking about the actual site location you choose or elements of site preparation – we’re talking about the actual region, climate, and zone where you are planning to grow. Elements of temperature, humidity, weather, rainfall, and more all play into what you can grow, as well as how you grow it, and even what accessories you should invest in.
What region, growing zone, or climate do you grow in? What accessories, materials, and other facets of greenhouse growing should you invest (or not) to create a masterpiece of production that flourishes without a hitch? The solutions and situations are many, but we simplify them all here, depending on where you grow in the US.
WHAT IS A GROWING ZONE?
Growing zones (or hardiness zones) help designate regions of the US where certain crops can be grown. They typically involve data on the last and first expected frost dates, season lengths, and average temperatures from region to region that allow for specific plants to thrive year-round, or to endure winters and cold seasons. Though they’re not 100% perfect or accurate, they’re nonetheless an incredibly useful tool for growers in knowing what they can or cannot grow in their area.
Greenhouse growers can defy the laws of nature to some extent, creating their own environments to meet the needs of their plants wherever they live, and no matter their growing zone. Still, growing zones can dictate what’s ideal, possible, and required of greenhouses to operate well. Beyond growing zones, climate patterns and rainfall in an area – an element not inherently part of growing zone data – will also have an impact, as well as microclimates within a growing zone.
GENERAL TEMPERATE TO SUBTROPICAL
Chances are that if you’re growing somewhere in the lower 48 of the continental US, you’re growing somewhere in zones between 3 and 7. On a lot of seed labels, the designation of zones 3-7 (or 4-6) are some of the most common ones you’ll see. These zones apply to most of the midwest and the south, some of the most generally agricultural land in the country.
Climate-wise, this extends to the cold semi-arid (far western Midwest and west), hot- and warm-summer humid continental (upper midwest and northeast), and some humid subtropical (lower midwest, south, southern Alaskan) climates of the country. Summers can get hot and humid, while winters can get quite cold, sometimes reaching subzero temperatures. Of course, the winter temperature limits get lower and lower the farther north you go.
For greenhouse growers in these regions, investing in both heating and cooling accessories is a smart bet to cope with the extreme temperatures possible in both summer and winter. Basic ventilation probably achieves enough for temperature regulation in summer, though people wanting to run more advanced, streamlined operations with sensitive plants may need more help to keep things cool beyond that.
The further north greenhouse growers live in these regions (such as the upper midwest and northeast), the wiser it is that they have a heating mechanism if growing plants year-round and through winter (especially cold sensitive crops). Further, these humid regions make it important to invest in some sort of humidity control, or a way to gauge it so it doesn’t get out of control. Especially if using wood as part of your construction or design, make sure to opt for strongly rot-resistant types.
DESERT/ARID TO TROPICAL
After temperate and some subtropical regions, you’re next likely to be growing in a desert, arid, or even tropical zone in the US. This applies to growing zones 8 to 11, which typically less usual agricultural areas in the country (save the San Joaquin valley of California). Since these areas have warmer and in some cases, drier, weather, this does lengthen the season you can grow most things, but some considerations need to be made.
Such zones extend to some cold semi-arid (west/southwest), cold desert, hot desert (southwest), hot semi-arid (west Texas), oceanic (Hawaii and Pacific northwest), warm- and hot-summer mediterranean (west coast), monsoon, savanna, rainforest (southern Florida and Hawaii), and some humid subtropical (lower midwest and south) climates. These do cover a much wider range of climates and subclimates, though they are concentrated in much smaller swathes of the country.
In these zones, weather tends to be warm year-round, with winter temperatures never falling below zero. Zone 8 (southern United States, the southwest) may allow most temperate plants to grow year round, only dipping as low as 10 to 20° F at the lowest. A zone 11 region (Los Angeles and Miami areas) very rarely drops below freezing (climate change pending), so the growing world is truly your oyster.
Wanting to greenhouse grow in these areas? In arid zones, you can take the back seat with construction and not have to fret about what types of wood you use, as you won’t be struggling with humidity so often (though check with irrigation). In humid tropical and subtropical regions, however, make sure that the lumber you select stacks up against fungal and rot issues.
Since these regions tend to be so warm year-round (save in some cold deserts, cold semi-arid regions, and subtropical southern states), heating accessories will probably not be on your list of needed greenhouse equipment, except to nurture sensitive plants in zones 8, 9, and maybe even 10. Blistering hot climates that are expected to top 100°F (e.g. hot deserts) should always either have climate control or shade cloth!
Last but not least, cooling accessories will definitely be useful in any of these zones. In more humid area meanwhile, methods for managing humidity and ventilation to keep down moisture and disease will really help your operation go the distance.
NORTHERN TO MOUNTAINOUS
When you live way up north – or way up in high altitudes – greenhouse growing is a whole different ballgame. In high latitude places, growing seasons are shorter due to more winter darkness and lower temperatures, a factor greenhouses can really help with by providing season extension. The same goes temperature-wise for high altitudes: even if your surrounding state or region is of a certain zone, it’s very likely that your mountain abode will abide by a whole different set of rules.
Zones 2 and lower apply to such regions. This includes warm- and hot-summer mediterranean continental, subarctic, and dry summer subarctic climates of the high altitude west, particularly the Rockies. It also governs the climate of most of Alaska, as well as the very far northern midwest and northeastern states of some hot-summer humid continental zones.
In a nutshell, winters are long, while summers are short in such places. Greenhouses naturally provide season extension and protection with their designs, while growers who want to produce year-round will absolutely have to invest in heating accessories: heaters, thermostats, even insulation and possibly more (accompanied with basic winter greenhousing tips). The farther north you go (especially in Alaska), lighting options are a must-have for winter production to make up for the lack of sunlight.
Despite colder average temperatures (sometimes reaching -40° F or more), summers in these regions can still get hot at the height of the season. Even parts of interior Alaska will reach temperatures of 90° F or more. Structures still require basic ventilation for temperature regulation, and cooling accessories can also go a long way – whether passive, climate controlled, or whatever works best for your operation.
Don’t be fooled or get too comfortable with your greenhouse setup just from a glance at a climate or hardiness zone map. While these maps are fairly accurate and helpful tools for growers about the places they’re growing in, the truth is that they don’t account for every last detail, climate pattern, or trend of average temperature, humidity, and rainfall in any given area. Why this is the case: microclimates.
Microclimates account for small patches or areas in larger regions that have slightly (or vastly) different traits than the broader climates in which they are found. In fact, a high-altitude area is a great example of a microclimate (tending to be colder), though you could take it even further: a mountain itself comprises two microclimates. Its north-facing side will create different environments for plants (and greenhouses) than its south-facing side.
For that reason, look into the climate and weather of your particular area as locally and specifically as you possibly can. Who knows: even though you live in a temperate zone, your specific area may experience more rain and humidity. Similarly, some river valleys or floodplains within certain regions may have lower temperatures than surrounding areas due to the way air moves through the landscape.
KNOW WHEREVER YOU GROW
Though greenhouses all achieve the same ends with their designs – creating better environments for your plants – where you end up building them regionally calls for different approaches, uses, and even accessories to be run successfully. Taking that a step further, it may even have an effect on what you choose to grow. Ask yourself before you buy, design, or build your greenhouse: would the crops you grow require the help of a greenhouse structure after all?
Hot weather plants in a cold region or low hardiness zone, for example, will need protection year-round, even heating accessories for growers to have a successful crop. But in a higher hardiness zone, they may not need such measures at all. Regardless, make sure to research your plant’s needs, your regional climate, your growing zone, and the greenhouse accessories available to you before making the investment.