What is a cold frame?

cold frame – also known as a hot bed – is a kind of tiny greenhouse. It can be built from wood, stone, straw bales, or other materials, with a clear lid made of glass, acrylic, or clear plastic.

cold frame

Just like a full-size greenhouse, a cold frame can be used to protect plants over the winter. It can also be used to extend the growing season, allowing the gardener to put seedlings outside earlier in the spring and continue harvesting crops later into the fall.

A cold frame is simple enough that it can be built as a do-it-yourself project. After that, it’s also easy to use.

First, put the cold frame in a sunny spot protected from wind. This will allow the cold frame to do its job most effectively. Sinking the cold frame into the ground will provide additional insulation, while sitting it on top of the soil keeps it portable.

Fill the cold frame with closely-spaced plants. The plants can be growing either directly in the soil, or in buried pots. Either way, the soil between the plants should be covered with mulch or leaves, to help moderate its temperature.

A cold frame is amazingly effective at absorbing and retaining heat. If the outside air temperature will be just 35°F, the top of the frame should be left ajar, to prevent the air inside the frame from becoming too warm. The top of the frame can be opened all the way if the outside temperature will clear 45°F. This is especially important in the spring – seedlings that don’t experience some bracing temperatures will have a tough time acclimating to life without protection when they’re moved out of the cold frame.

The warmth inside a cold frame tends to have a drying effect on the soil, so it’s important to keep the plants well-watered. Be careful not to water too much in the winter, though. Plants that are not actively growing don’t take up water, and their roots can be damaged by the soggy soil.

Finally, don’t forget about your tiny greenhouse when it gets buried by snow or fallen leaves. Clear off the top so it can continue to do its job of absorbing sunlight and keeping your plants warm.

What is a cold frame?

What is aquaponics?

Some natural gardeners focus on creating habitat for wildlife in their yards. Others focus on using their land to produce food for themselves. Within this second strain of natural gardening, growing fruits and vegetables is relatively easy (though some homeowners do find themselves in the bizarre situation of being threatened with jail time for having a vegetable garden in their yard). Raising meat at home is much more challenging: most towns don’t allow residents to keep cattle, pigs, or goats in their yards, and chicken-keeping is often limited to a small number of hens.

One solution to this problem is fish.

Yes, fish. It’s usually legal to keep them in your yard, even if you plan to eat them. As added bonuses, fish are easy to care for, and they don’t get diseases that can be transmitted to humans.

Once people realized that they could raise fish in their yards, they quickly came up with an even better idea called aquaponics. Aquaponics is the practice of raising fish and plants together. The fish live in an above-ground tank, and the plants grow in racks suspended along the water’s surface. Adding fish food once or twice a day jump-starts an efficient and productive system: the fish turn the fish food into fish growth and fish waste, and the plants turn the fish waste into plant growth and clean water.

Within a few months, the plants and fish become people food. Buying young plants and fish and raising them in this way is cheaper than buying similar food at the grocery store, so the practice is cost-efficient – plus, you know exactly where the food came from.

The system is mostly vertical, so it uses space efficiently. And it can be energy-efficient too. First, choose fish and plants that don’t mind cold temperatures. Green, leafy plants like lettuce, spinach, and herbs (sage, parsley, and basil, for example) work well. Then, build the system in a greenhouse in a sunny spot in your yard. This way, it will mostly heat itself.

Keeping the system running is not difficult. The plants will need adequate light and humidity. The pH value of the water must be safe for both the plants and the fish. And the water will need to be warm enough. If the air temperature around the system is cooler, that’s usually no problem.

Novice aquaponics practitioners might be inclined to begin with a small system, but larger ones are actually easier to manage. A tank that holds less than 100 gallons will experience faster swings in temperature, pH, and bacteria populations than a tank with more water, and will require more active management.

Overfishing and industrial fish farming are both serious environmental problems. We can enjoy fish more sustainably by raising it ourselves.

What is aquaponics?

Why don’t we see much wildlife?

Many people would like to see more wildlife – especially butterflies and songbirds, but maybe also chipmunks and deer and foxes – in their yards. Why are these animals so scarce in our neighborhoods?

One reason is that there are just far fewer animals on our planet than there used to be. Studies have found that animal populations – that is, the number of individuals of each species – have, on average, decreased by half since the 1970s. Buffalo used to roam North America in the tens of millions; now there are only a few hundred thousand. Passenger pigeons, it is said, used to blot out the sun as they flew overhead; now there have been none at all for over a hundred years. And in an anecdote of our own times, truckers are certain they used to pick up more bugs on their windshields as they drove cross-country.

A second reason is that as we destroy natural habitats to make more room for roads, houses, and lawns, the animals that used to live in our communities move elsewhere. As earlier posts have explained, few animals can make a living in turf grass. When that is all we offer in our yards, we won’t see much wildlife around our homes.

A third reason we don’t often observe animals in our yards is that animals are increasingly becoming nocturnal, exactly because they don’t want to be around people. A recent study found that mammals are shifting their activity to the nighttime hours, becoming on average a third more nocturnal than they used to be. That is, an animal that used to do 50% of its daily activities while the sun was up and 50% after dark is now splitting its time about 33% – 67%.

The researchers found that this shift is happening across species, continents, and habitat types. As an article on the study puts it, “antelope on the savanna of Zimbabwe, tapir in the Ecuadorian rainforests, [and] bobcats in the American southwest deserts” are all changing their schedules in an effort to avoid humans.

This turned out to be true when avoiding humans was a challenge for the animals – animals living in undisturbed areas aren’t changing their historical habitats. But the researchers found that animals went out of their way to avoid humans not only in places where humans are doing dangerous things, like hunting, but also in places where humans are doing innocuous things, like hiking and farming.

This shift in activity is a problem because animals that have adapted to being active during the day may not fare as well when they try to carry out their routines at night. In the dark, it may be more difficult for them to find food, evade predators, and communicate with other members of their species.

The changing patterns of animal activity also diminish our opportunities to see wildlife. If we want wild animals to thrive – and if we want the chance to encounter them as we go about our own daily routines – we must find a way to live much more lightly on our planet.

Why don’t we see much wildlife?

When do birds migrate?

We all know the answer to this one: birds migrate in the fall. That is when we see those iconic V’s of honking geese winging their way south. But why don’t we see other kinds of birds flying towards warmer climes? When do they migrate?

The answer is that other birds also migrate in the fall. But they do it at night.

Migrating under the cover of darkness is a smart strategy for many small birds. Flying predators, like hawks and eagles, tend to be active during the day. By making their long-haul flights after the sun goes down, small birds can avoid getting eaten along their journey.

Unfortunately, migrating at night comes with other dangers. Many birds use the stars to navigate on their long trips, and when they see lights closer to ground level, they can get confused and fly in circles until they exhaust themselves. Or they may simply crash into a lit window.

When we think about birds crashing into windows, we often think of glass-covered skyscrapers in big cities. In fact, most bird-window incidents occur around buildings that are less than four stories tall. In other words, migrating birds collide with ordinary houses more often than they collide with high-rises.

By dimming our lights on fall evenings – or by closing our curtains – we can help birds arrive safely at their destinations.

When do birds migrate?