Building Your First Greenhouse

There are plenty of reasons to build a greenhouse in Alaska if you don’t have one. Having a greenhouse could extend your growing season, give you a place to grow starts (if you have a way to heat it), or allow you to grow warm-season crops like tomatoes, peppers, and cucumbers with ease, as well as to eat other crops earlier than you otherwise would. 

But growing in a greenhouse requires more management than an outdoor garden. When it rains, it will not water your greenhouse plants. When it’s hot, you’ll need to make sure it doesn’t get too hot. When it’s humid, you’ll need to ensure adequate ventilation. Pests can multiply quickly in a greenhouse and can be hard to eradicate once there. But those are all manageable problems.

attached greenhouse with lots of plants growing

Before we get to that, first, what type of greenhouse will you build and where are you going to put it? Your location might be partly dictated by where you have room in your yard, but hopefully you can build your greenhouse in a place that optimizes light and heat from the sun too. It sure doesn’t hurt if it’s convenient to get to as well to make harvesting and management easier. The most convenient option could be an attached greenhouse, but there are pros and cons to freestanding versus attached greenhouses and many styles to consider.

shed roof greenhouse with garden

Next, you’ll want to think about the type of greenhouse structure you want to build. Here are some ideas on the wide variety of structures you may want to build. Once you have a basic idea of what you want to build, you’ll have the option of either purchasing a kit greenhouse or starting from scratch. In this 200 page handbook, you’ll find step-by-step plans for building most types of home greenhouses. Here, you can read about some interesting designs used by Alaska Master Gardeners as well as some of the challenges and joys of owning a greenhouse in Alaska.

standard greenhouse with tomatoes inside

A couple of the key things to manage in a greenhouse are ventilation and temperature. For those of us who like to leave town during our short Alaska summers, that can get tricky. But there are a couple of ways to automate these tasks. There are simple louvers or vent openers that rely on wax-filled cylinders or solar sensors to open and close vents at certain temperatures. This is a huge stress and time saver.

Something else that will help you care for the plants in your greenhouse easily is drip irrigation. Unlike an outdoor garden when it rains, it unfortunately does not water the plants in your greenhouse. However, the humidity in a greenhouse is higher than outside, which can help plants in a greenhouse compared with an outdoor garden where a windy, sunny spring day will parch your garden to a crisp in hours.

You may have more issues with pests and diseases in your greenhouse than you’ve had before. You can get help with pest identification here. In general, keeping things clean in the greenhouse, scouting for pests early, and keeping water off the plant foliage will help control pests.  

One of my favorite resources for greenhouses in Alaska is the Biomass-Heated Greenhouses: A handbook for Alaskan Schools and Community Organizations. As the name implies, the handbook is geared toward community organizations and schools, but there is a wealth of information for any greenhouse owner (biomass heated or not). Another resource, also useful for home greenhouse owners, but intended for educators is the Greenhouse Manual: An Introductory Guide for Educators

If you’re not ready to build a greenhouse yet, you can save money and get by with various season extension techniques.

Previously published in the Fairbanks Daily Newsminer June 12, 2022.

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