Season extension

Farmers want to grow food for a long time. They use special tools to help plants stay warm.

Some use tunnels made of clear plastic. These tunnels keep out the wind and ice. Some tunnels are tall enough to walk in. Others are short and low to the ground.

Other farmers use light cloth to cover crops. This cloth lets rain through. It keeps the frost off the leaves.

Some people use old windows to make small boxes. These boxes protect young plants. They help the plants grow in the spring.

Plants also like warm soil. Adding straw or leaves helps the soil stay warm. This lets farmers grow food even in the cold.

Farmers want to grow food for more months each year. This is called season extension. It helps crops grow past their normal time.

Some farmers use unheated greenhouses. These are also called cold houses. They protect plants from wind, snow, and ice. These structures can help hardy vegetables grow through winter. Some greenhouses use solar power to stay warm. They use the sun to keep the air inside cozy.

Farmers also use tunnels made of plastic. Low tunnels are short. They are only 2 to 4 feet tall. High tunnels are much bigger. You can walk inside them. Some even fit a tractor!

Light cloth can also help. These are row covers. They keep frost off the leaves. They let rain pass through the fabric.

Other ways keep soil warm. A cold frame is a small box with a clear roof. It protects young seedlings. Farmers also use mulch. This is material like straw or leaves placed on the soil. Mulch helps the ground hold onto heat. This lets plants grow earlier in the spring.

Farmers want to grow crops for more months each year. This practice is called season extension. It helps plants grow beyond their normal outdoor time. Some people use this to grow food in colder months. Other people use it in places with rainy seasons. This extra time can help a grower get more food. It makes the growing year much longer.

There are many ways to keep plants warm. Unheated greenhouses, or cold houses, protect against wind and snow. They can keep hardy vegetables growing into the winter. Some greenhouses use passive solar design to stay warm. This uses the sun to keep the air cozy. Other systems use heat stored in the ground. These are called climate batteries or geothermal systems.

Plastic tunnels are another helpful tool for farmers. Low tunnels are short and only 2 to 4 feet tall. You must lift the plastic to reach the plants. High tunnels are much larger buildings. They are tall enough to walk through easily. Some are even big enough for a tractor. Some tunnels have two layers of plastic. This helps trap heat inside the structure.

Lightweight fabrics called row covers are also used. They are placed over plants to keep them warm. These covers let rain pass through the fabric. They also let plants breathe. A row cover can let frost form on the cloth instead of the leaves. Small gardens might use even simpler things. People use glass cloches or newspaper cones. They might even use baskets or hay.

Keeping the soil warm is just as important. Mulch is material placed on the soil around plants. Farmers use organic mulch like straw or compost. Synthetic mulch is often clear or black plastic. Raised beds also help plants start earlier. These are beds where soil is piled higher than the ground. The soil in these beds heats up quickly in the spring. This allows for much earlier planting.

Season extension is a vital practice in agriculture. It allows farmers to grow crops beyond their natural outdoor growing seasons. This method provides extra time for harvesting. It can also be used to grow food during rainy seasons in certain climates. Most crops stop growing when daylight drops below 10 hours. Season extension helps bypass these natural limits. Growers use various tools to manage temperature and light. These methods ensure plants can thrive even when the weather is harsh.

Many techniques rely on unheated structures. These are often called cold houses or unheated greenhouses. They protect plants from freezing temperatures and drying winds. They also shield crops from frost, snow, and ice. These structures can extend the season for hardy vegetables into the fall. Sometimes they even last through winter until spring. If temperatures inside drop below 32 degrees Fahrenheit, supplementary heating might be used. This keeps the environment stable for the plants.

Some greenhouses use passive solar design to stay warm. These are called passive solar greenhouses. They use thermal mass to keep the air warmer on overcast days. They also stay warmer at night. Other advanced systems move heat from the ground to the greenhouse. These include ground-coupled heat exchangers and thermal chimneys. Some use thermosiphons or "climate batteries" to store ground heat. These methods provide energy without using much fuel. They represent an elegant way to manage heat.

Polytunnels are another common type of structure. They consist of curved frameworks covered in thin polyethylene plastic sheeting. There are two main sizes of these tunnels. Low tunnels are only 2 to 4 feet tall. A person cannot walk inside them and must lift the plastic to reach plants. High tunnels are much larger commercial buildings. They are tall enough for people to walk through easily. Some are even large enough to operate tractors inside. Some high tunnels use two layers of plastic. Air is blown between the layers to increase insulation. This process can reduce the amount of sunlight reaching the plants.

Row covers are lightweight fabrics used for frost protection. They can be placed directly on crops as floating row covers. They can also be placed over hoops or wires. These fabrics allow rain to pass through easily. They also allow plants to transpire, which means they can release moisture. This is different from plastic sheeting which holds moisture in. A row cover works by letting frost form on the fabric instead of the leaves. Outside covers must be clipped, pinned, or weighted down. Inside covers can simply be draped to the ground.

Smaller gardens often use temporary coverings for protection. These include glass cloches or newspaper cones. People may also use baskets, plastic bits, or mulches. Mulches like hay, leaves, or straw are pulled on and off daily. Mulch can also be applied directly to the soil. Organic mulches like straw or compost help retain heat. They can also add heat through decomposition. However, growers must be careful with animal manure. It can cause chemical or thermal burning. It can also introduce coliform bacteria. Using aged compost is often better because it is safer.

Soil management is another way to extend the season. Raised beds are areas where soil is piled higher than the surrounding ground. This soil can be more than a foot deep. Because the soil is loose and elevated, it heats up faster in the spring. This allows for much earlier planting. Hotbeds are another method using heat from compost. A mass of hot compost is placed under a thin layer of soil. The plant grows directly above the rising heat. Both methods help plants start their life cycles sooner. This maximizes the total growing time available to the farmer.