Here in the US, we don’t really spend time imagining serious food shortages affecting our daily life, but the disruptions of the recent pandemic and continuing fallout from supply chain problems, drought, and conflicts around the world have certainly made us less complacent. Gardeners say they’re drawn to the sense of stability and control that producing their own food provides during these still-uncertain times. But how do you plan for an efficient, well-managed garden/greenhouse that can be expected to satisfy your needs during a significant food shortage?
Determine Your Needs
Location
Your needs for a garden set-up are highly dependent on your location. In regions with stable weather patterns that don’t experience cold winters, an outdoor garden may provide all you need year-round. Florida and the San Joaquin Valley in California are good examples. Of course, even Florida occasionally experiences freezing temperatures as far as Fort Lauderdale. In California, volatile weather patterns induced by climate change power a disastrous cycle of drought, wildfires, and flooding. Even in these states, many crops can be better protected in some sort of greenhouse setup.
Cold Frames
Fortunately, it’s not necessary to build a fancy Victorian glass house to produce and protect your food crops. In fact, some crops are perfectly happy in the semi-protected environment of a simple cold frame. Cold frames are primarily used to protect plants from strong winds, excessive rain, and cold temperatures. They can be used to start seeds as much as 6 weeks early in spring or to extend a growing season well into fall.
Cold frames are simple structures and easy to build. Basically, a cold frame is a low box with a slanted transparent roof that can be raised or lowered by hand. When the top is closed, it prevents heat from escaping, particularly at night. Early in the growing season, cold frames may be closed nearly all the time, so they should not be constructed to be airtight. Cold frames should be placed in a sunny, sheltered location and they should be oriented so the slanted roof faces south.
Because cold frames are easy to build and are inexpensive, they’re great to use in your traditional garden; especially if they can be removed as the plants grow or the temperatures warm up. Carrots, leafy vegetables, strawberries, leeks, and radishes are all well suited to cold frames.
When building cold frames, you have a wide choice of materials to suit your budget. For example, the frame can be built from anything from naturally rot-resistant redwood or cedar, to scrap lumber, PVC pipe, or plywood. For the transparent roof, you could use old windows, polycarbonate panels, or flexible polyethylene film. Many plastics turn yellow over time in the sunlight, so look for options that have protection against UV rays if you want your cold frame to last.
Do you live in a town or city apartment without a yard or access to a rooftop for establishing your garden? One great advantage to cold frames is that they are small and versatile. If you have a porch or balcony with sun exposure, a cold frame or two may be the ideal solution that will allow you to grow your own spinach, lettuce, or even strawberries. Accompanied by a few tomato plants in pots and a selection of your favorite herbs, you’re well on your way to enjoying the fruits of your own labor.
Greenhouse Framing
When establishing a new greenhouse, you have choices to meet a variety of needs, from the amount and configuration of available space to the budget you’re ready to devote to the project. Keep in mind that it’s best to be prepared and complete your project before a crisis hits, while materials are still available and affordable, not to mention so your garden has a chance to get established!
The most durable greenhouses start with a foundation and sturdy frame. A solid concrete foundation with drainage helps prevent muddy, saturated floors during rainy seasons or after watering or cleaning, keeping risk of plant disease low. With a full solid foundation, you’ll need to keep your plants in pots or raised beds rather than directly in the ground, but damage from erosion can be essentially eliminated. Alternatively, you can lay a concrete walkway that runs the length of the greenhouse, leaving natural dirt beds on either side.
Frames constructed of regular lumber are not exceptionally durable in the long term since exposure to high humidity and dampness will eventually lead to rot and damage from mold and mildew. Some DIYers are comfortable using pressure-treated lumber, but others are uncomfortable working in an enclosed space exposed to the chemicals in pressure-treated wood. Rot-resistant woods like cedar, redwood or cypress are often better options and are also naturally insect-resistant. These woods are relatively easy to work with and quite popular for DIY greenhouse builders.
Frames made of PVC piping are inexpensive and easy to assemble for the DIYer but are typically too light to withstand high winds or storms. Plan on using rebar to attach the frame to the ground to prevent it from sailing away during heavy summer storms. UV treatment on PVC not only protects the material from degradation, but it also allows the PVC to act as a good insulator. PVC is not particularly strong, so it’s wise to go with a thicker pipe size to add rigidity or reinforce the corners of the frame with rebar for support.
Frames made of steel are heavy, expensive, and pretty much overkill for anything but large commercial greenhouses. Aluminum, on the other hand, is lightweight and won’t rust, but it’s not a good insulator and you can lose a significant amount of heat through the frame. Aluminum isn’t strong enough to handle heavy snow loads or other extreme weather. Unfortunately, the current aluminum shortage probably renders this solution impractical anyway.
If you’re planning on building a hoop house, PVC is almost certainly the way to go, since the material is naturally somewhat flexible and can be easily formed into hoops. Again, it’s wise to anchor the hoops to the ground with lengths of rebar.
Greenhouse Covers
Options for greenhouse covers are ever-expanding as interest in both hobby and commercial greenhouses continues to grow. For a backyard greenhouse, glass is not the best option since it’s expensive, fragile, and can be difficult to customize (high insulating double-pane windows, for example, cannot be cut to size without losing their insulating qualities. Glass is heavy and requires strong framing, and we’ve already experienced a glass shortage during the COVID era in 2020-2021. Material shortages can not only make building your greenhouse difficult and expensive, but material for critical repairs can be even more so.
Rigid fiberglass or plexiglass is strong, lightweight and easy to cut and customize, but the surface is relatively soft and over the course of a few years, it may collect scratches and embedded dirt which limits the amount of light that can get to your plants. During COVID, skyrocketing demand, catastrophic weather and logistical problems contributed to a worldwide shortage of resin that triggered record-breaking price inflation. The situation is easing but should be kept in mind if you’re planning on putting off building your greenhouse until another crisis rears its head.
Acrylic or polycarbonate sheets offer good light transmission, and they come in double layers sandwiching a dead air space. This configuration substantially increases the insulation factor, beyond that offered by traditional glass or even fiberglass. But even acrylics were in short supply in the US during COVID, where bitterly cold temperatures in Texas caused severe damage to chemical plants which left them inoperative for weeks.
Plastic sheets and clear films are very lightweight and easy to install, but most are significantly less durable than their rigid cousins. Greenhouse films like PVC that are typically available at your local garden supply store generally only last a few years before they turn yellow, become brittle, and need replacement. Clear greenhouse films fabricated by BTL Liners are reinforced to prevent tears, engineered to resist UV degradation, and designed to offer maximum light transmittance. An available anti-condensate coating prevents the collection of moisture on the interior side of the film, which means that light transmits to the interior evenly without shadows or lensing effect as sunlight travels through water droplets.
Of course, production of plastics like PVC and polyethylene (the most widely used plastic in the world) are also suffering from the winter storms in Texas. Texas produces 85% of all polyethylene in the country, so the effects of extreme weather, including a 2021 hurricane season that saw six landfalls on the gulf coast complicated an already reeling plastics industry.
