Gardening has always been a popular hobby, and these days the concept of self-reliance or simply increasing your food independence is increasingly popular. Being able to grow your own vegetables will save you a lot of money. Unfortunately, seasonal weather doesn’t always cooperate. Especially if you live in the northern states.
Still, a little resourcefulness can go a long way toward either extending your growing season beyond what Mother Nature allows. In some areas, you might even be able to maintain a continuous growing season. If you’re going to have any chance of truly pulling something like this off, then you’re going to need some type of greenhouse.
Of course, the tern “Greenhouse” is a very large umbrella term that people tend to throw around ad hoc to describe any sort of plant protective shelter that manages to let some light in. To really understand the different types of greenhouses, and what they are best used for, we’re going to have to roll up our sleeves and get familiar with some ground-level terminology.
What Is A Seed Starter Greenhouse?
This is a very simple device that isn’t technically a greenhouse at all. It’s really just a durable plastic tray with a clear, removable top that let’s light in. A lot of times they are sold as a kit, complete with water-absorbent seed plugs and a low wattage heat mat.
You hydrate the seed plugs with warm water. Then you insert your seeds to the depth on the package, and you plug the heat mat in. It maintains the consistent warm soil temperatures that most seeds prefer for fast germination.
When they do sprout, you need to take the seedling and it’s peat plug out to pot it up in a seedling container. With most seedlings, if you leave them in the heated seed starter greenhouse for more than 24 to 48-hours, they will grow too fast and get “Leggy.” This is a condition that causes the stems to grow too long, too fast. The lack of structural integrity leads to them falling over and dying within a few short days.
So, if you do want to start your own seeds from peat plugs, make sure to keep quality potting soil and seedling cups close at hand. As your seedlings sprout, you can pot them up and put them in a sunny window or under some quality grow lights.
Best Seed Starter Greenhouses
Cold frames are the old fashioned way of protecting and hardening off young seedlings in the spring. Many avid gardeners then repurpose them again in the fall to extend their outdoor growing season. Depending on where you live it can be an excellent way to extend your total growing season time by as much as three to four months! Not to mention being able to enjoy tender herbs like basil deep into November or giving your tomatoes an amazing head start next spring.
Some people, including the old grandmas who survived the Great Depression simply improvise them out of old window frames. A hinged top gives you access to the interior to tend the plants. It also lets you air things out on a hot and sunny day to keep the tender plants from frying
In today’s world, chances are your local homeowner’s association isn’t going to look too fondly on a bunch of improvised old windows screwed together with hinges laying in your front yard. Thankfully, gardening equipment manufacturers have gotten wise to this age-old gardening innovation, and now offer tasteful-looking options that use superior materials.
Best Cold Frames For Protecting Seedlings to Extend Growing Season
Miniature Walk-In Greenhouses
The next step up from the cold frame is the miniature walk-in greenhouse. This is a frame with some relatively sturdy shelves meant to hold seedlings in the spring to harden them off and give them a good head start. Then depending on what you’re growing and where you’re growing them, you can even use the mini walk-in greenhouse to add a few more months to the end of the growing season.
The exterior skin or shell of a mini walk-in greenhouse, and it’s overall size will influence the price, as well as the thermal efficiency. A mini walk-in greenhouse with a clear plastic skin might be relatively inexpensive, but it’s not going to hold in a lot of heat during a hard spring cold snap. If the temperature outside is forecast to dip below 32-degrees for more than say 6 to 8 hours, you will need to plan some type of heating method to keep warm-season plants from suffering frost damage.
Beyond the fact that it’s relatively inexpensive, a mini walk-in greenhouse with clear plastic sheeting is also relatively lightweight. You should be able to put it together
On the other end of the spectrum, a mini walk-in greenhouse with a rigid polycarbonate shell will do an excellent job of holding in heat. Even if temperatures dip below 32-degrees for a full 24-hours, you might be able to keep the interior of a polycarbonate mini walk-in greenhouse warm by simply placing five-gallon buckets of hot water in the four corners.
Of course, the tradeoff here is that you’re going to pay more for a high-quality greenhouse made from polycarbonate. It’s also the sort of thing that takes a while to put together and take apart. So, if you’re not going to be using it in the heat of summer, you’ll need to figure out where to store this relatively heavy miniature greenhouse.
The Best Mini Walk-In Greenhouses
The Benefits Of Shade Cloth
With a miniature greenhouse, you have to keep in mind that you are essentially managing an interior environment. While the prevailing notion is that you need to worry about keeping the interior warm during cold days and the dark of night, a hot, sunny day is just as much of a threat to delicate seedlings. Especially, with young plants that haven’t hardened off and heat-sensitive plants like radishes, salad greens, and cilantro that will “Bolt” to seed if their soil stays too warm.
One way to keep the sun from overheating the interior or sun scalding the leaves of your plants is to install a shade cloth along the interior ceiling. This will essentially limit the amount of solar energy that comes into the greenhouse, while still letting enough through to keep the plants growing vigorously. You can then open the greenhouse roof vents to let excess hot air out during the afternoon, then close it in the evening to preserve warmth during the cold of the night.
In a pinch, you can try to improvise a shade cloth out of some old bedsheets. Still, you’ll find better results from a commercially made shade cloth, which is relatively inexpensive, and you can even find them rated to allow a certain percentage of light through. This is nice for the seasonal changes your mini walk-in greenhouse is likely to experience.
For example, you might want to set up with a lower percentage shade cloth early in the spring when the strength of the sun is weak. Then you might want to switch to a higher percentage shade cloth as you get into May and June when the sun is very strong, and your plants are at risk for overheating or damage to the leaves from excess exposure.