Aquaculture and Season Extension

Aquaculture: getting Food from Water

This class was created by Marit Parker and Heather Jo Flores

How to increase yields and perpetuate self-reliance by building clever structures that harness natural energy

Aquaculture is usually defined as farming fish and/or other aquatic plants and animals. Even on a small scale, a pond alters the landscape, changing the light and even altering the surrounding temperature. Aquaculture of any sort increases habitat and diversity, and can have a big impact on the local ecosystem.

Ecological design takes a holistic view, so aquaculture systems are often an integral part of wider systems, with ponds irrigating horticultural systems and providing drinking water for livestock, while ducks are on slug patrol. Ideally, everything is designed to run by gravity, without the need for mechanical assistance from pumps.

Aquaponics

Defined as “a food production system that couples aquaculture with hydroponics whereby the nutrient rich aquaculture water is fed to hydroponic grown plant, involving nitrifying bacteria for converting ammonia into nitrates,” aquaponics, when designed carefully, can radically increase the yield of your project.

Here are two photos from the Radix Center in Albany, New York, where Stacy Pettigrew and her partner Scott Kellogg have created a large eco-shelter type greenhouse in the heart of the city, with systems that includes an aquaponic system and rabbits raised for their meat, heat, and CO2.

Ponds of all sizes are a common and highly-useful component of many different types of sites.

If you have access to land that isn’t tiny, you are quite likely going to want and need at least a small pond somewhere in the system, so you may as well grab a few quick pointers about pond design in general.

Earthworks like swales and keyline design, connected to your home water system, work especially well when interconnected with a pond and/or aquaculture system, so look for opportunities that make sense on your site.

General rules for pond design:

• Store water as high on site as possible, and divert it as many times as possible between the source and the sink.
• Do the research to learn about the ripple effects before you introduce non-indigenous fish, amphibians, and pond plants into your system, as these species can be especially adept at expanding their population.
• Remember that a big pond is also a big hole, and holes can be dangerous! Plan accordingly.

Because these designs are so intensely site-specific, this is one area we can’t really teach you much about within the scope of an online course. If you want to include ponds, aquaponics, and/or other types of aquaculture on your site, the very best way for you to learn about how to do that will be to search out and visit local examples and, if possible, enroll in some courses that are entirely focused on the topic, as it can be a bit of a learning curve. Yes, mistakes are tools for learning but big, waterborne mistakes can lead to big, waterborne disasters such as a local explosion of disease-carrying mosquitos, or worse.

Tune into the ecological principles, and make slow and small decisions that make sense for your site, rather than digging a huge pond in the middle of your land without really making time to develop a clear design for it.

Sometimes (often) aquaculture is a necessity, installed as a way to mitigate surplus water onsite. Check out this short video from Maddy Harland, about how to make a rain garden:

​Season extension: creating microclimates to extend the harvest

In industrialised nations we have become used to being able to buy every type of fruit and vegetable all year round. When you grow your own, you quickly become aware of the limits to what you can grow in your area because of the seasonal nature of gardening.

​Different crops are ready at different times of the year, with summer being the main season for the majority of crops. The further you are from the equator, and the higher your altitude, the shorter that precious summer season will be, and you may experience a hungry gap when few fresh vegetables are available.

Choosing varieties that grow and ripen at different times of the year is the first step in extending the season, as well as having some varieties that store well through winter. Traditional and heritage varieties show their strength here as they have been carefully developed through seed selection to thrive in different microclimates and seasons.

How to make your own microclimates

You learned about microclimates in Klaudia’s module, and this section is meant to pick up where she left off…

Season Extension is accomplished by making your own microclimates. To do this, first of all you need to get to know the different microclimates that already exist on different parts of your plot. Where are the sun traps and the frost pockets? Once you know your plot well, the next stage is to protect and develop these existing microclimates. For example, will a gap in the hedge allow frost to flow downhill, away from your plants? Will a trellis on the sunny wall mean you can grow fruit from warmer climes?

Why is this important? Because when you know how to make your own microclimates you can:

• Sow seeds early and get plants started while it’s still too cold to grow them outside.
• Grow plants that don’t normally do well in your climate.
• Keep crops going later into the season, often for months after they would have perished in winter freezes.
• Increase your yield, vastly and quickly through these actions.

Which tools you choose depends on what you want to grow and the climate, geography and altitude of your region. 

There are several ways to create microclimates on your site:

Hedges and windbreaks. As you learned in the Forests, Gardens, and Forest Gardens module, adding a hedge or windbreak can transform a garden. That’s because they create microclimates that are a huge benefit to humans, animals, and plants. While a wall seems to stop a wind completely, there are then eddies and swirls around it, whereas a hedge or windbreak allows a small amount of wind through, enough to stop swirling. However, the wind that passes through a hedge is at a slower, more gentle speed. Wind can cause a lot of damage to plants and not just by breaking them or knocking them over. Wind can dehydrate plants, and salty winds can burn them, leaving the leaves damaged.

Hedges also provide habitat for wildlife, increasing the biodiversity of your plot, which means you will have lots of predators on hand to eat up pests and help keep the ecosystem in balance.​

If you are planting a new hedge, or filling in gaps of an old hedge, think about what you want to include in it.

What native trees and shrubs would benefit your garden’s wildlife?

What plants would mean that, instead of losing part of your plot under the hedge, you are gaining an edible feature?​

Cloches. A cloche is a mini-glasshouse or polytunnel designed to cover one row or bed, or even a single plant. They give frost protection to the plants they cover, and can save plants when an unexpected late frost is forecast. Using them also means seeds can be sown and plants planted out a bit earlier.​

This video by Tamsin Westhorpe introduces a few different types of cloche.

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Cold frames. A cold frame is a small box with a hinged top covered in glass or plastic. They are often built with a used window, with a stick to prop the window open on a warm day. The sides can be made from bricks, wood or, for a well-insulated cold frame, straw bales. They are like a small greenhouse, just big enough to provide a protected space for small plants in pots.

Remay (fleece) and row covers. Remay or gardeners fleece is a very light weight cloth that allows moisture and sunlight through to the plants, while protecting them from frost. It comes in different weights depending on zone needs for frost protection. It is simply laid across the tops of the plants.

Alternatively, fleece/remay can be laid over small tunnels made with heavy gage wire. These same tunnels, if strong enough, can be turned into cloches by covering them with plastic. It is always best to use a ultraviolet treated plastic that will last several years, because cheap plastic that is not meant for growing will quickly disintegrate within one to two years. Tempered glass is best and the most sustainable if properly constructed, but will make the cloches heavy.

Greenhouses

A super simple cloche or cold frame can work wonders for extending the season, and even a tiny pond or water garden can produce a ton of food. But truly, if you want to create a beautiful, productive, inspiring, and multifunctional space on your site, you simply must build a greenhouse. Whether it’s a tiny makeshift hothouse you can barely stand up in, or a hundred yard high tunnel filled with mature trees, a greenhouse will increase the diversity, yield, and enjoyment of just about any site.

Top ten reasons to build a greenhouse:

1. Start seeds early (and late!) Many seeds need warmth to germinate and develop into healthy seedlings. If the growing season is short, getting ahead can make a big difference.
2. Protect tender perennials and grow exotic plants. Increase your yields by extending the range of plants you can grow in your climate!
3. Protect early blooming fruits (like apricot) from heavy rains. Flowers on fruit trees are often quite delicate and can be damaged by rain, wind or frost, resulting in big losses to your fruit crop for that year. Choose dwarf varieties and plant them right inside the greenhouse.
4. Covered space for propagation and transplanting projects. Some plants respond well to a bit of nurturing, resulting in stronger, healthier plants. And gardeners also respond well to a warm place to work on a cold day! Choose a corner of your greenhouse to double as a potting shed and you’ll spend less time carrying seedling trays around.
5. Channel heat into your living space in winter. Build a lean-to greenhouse built against the sunny wall of your house and enjoy the extra warmth in the house.
6. Indoor/outdoor space for messy projects. Leave an open area in a section of a larger greenhouse and you’ll find that you use it all the time, for all sorts of projects.
7. Zen gardens! There is nothing like a high-ceiling greenhouse full of blooming, tropical, edible, aromatic, and succulent plants. Build your own mini-arboretum and escape to it when you’re feeling down. A mentor of mine even had a tiny office in his greenhouse, where she would go to get away from the family and write.
8. Secure medicinal and high-value plants. A well-built greenhouse with a locking door helps keep both animal and human marauders from making off with your crop.
9. Increased humidity for mushrooms, aquaculture. Some greenhouse designs include extra moist, dark, humid zones for cultivating edible mushrooms. Aquacultures also enjoy a more humid environment, and doing something inside a greenhouse could also allow you to add powered pumps, lights, and other features.
10. Guest housing! Sleeping in the greenhouse when it’s full of plants is the best!

You can plan space for propagation (seed starting) in a larger greenhouse, or build something intended especially for getting a jump start on the season. For convenience, or for simple ergonomics, this should be a bench or shelf. Extra lighting can be installed and/or heat mats are needed in more Northern climates. In temperate climates this may not be necessary.

Case study: here’s a gorgeous little video with Susan at Polukrub in the UK, sharing about her temperate climate greenhouse.

Generally your greenhouse should be attached to your home or nearby, in your zone one area, because you will need (and want) to go there every day, and because you can use the greenhouse to send surplus heat into your home, and vice versa. Trust us on this: splurge on building a huge greenhouse/patio/outdoor shower and art space into your central living space and you will never for one second regret the decision.

Larger greenhouses of a more agricultural nature, with large beds built into the ground and used for preservation crops such as tomatoes, peppers, or fruit trees, should be placed in zone two, since it can be a bit of an eyesore.

Any greenhouse that is in constant use throughout the seasons, in particular if it is filled with more permanent perennial crops, other factors need to be considered year round:

Temperature control. When choosing or designing a greenhouse or polytunnel, it is important to ensure there are sufficient doors and windows that can be opened on warm days. It is surprising how quickly it can get really hot inside, often way too hot for both humans and plants! On the other end of the spectrum, (unless your greenhouse is heated in winter,) if you live somewhere with extreme cold, or if you have particularly delicate plants, more heat can be captured by insulating the greenhouse with a double wall plastic or glass. Recycled bubble wrap can be used for small areas, and combining techniques such as white walls, rock mulches, and even a cold frame or some cloches inside your greenhouse, can make a difference to whether your plants live or die.

If you live in a zone with high elevations, where winter weather sets in early and the permafrost levels go deep, the most energy efficient way to capture heat is by digging well below that permafrost level, preferably into a south facing hillside. Then, make raised beds within the greenhouse using compost. For most small-scale home-system greenhouses, raised beds are a good option for efficiency, either filling them with a good quality, bought compost, or ideally with your own homemade compost. I prefer French double dug beds integrated with high quality, on farm made biodynamic compost. Others prefer no-dig beds.

In Bolivia, this idea has been taken further, creating Walipini greenhouses. Walipini means place of warmth in Aymara, an Indigenous language of Bolivia. Tiffany Mok illustrates their design and shows them in use across the world, from Ladakh to Canada, in this short video.

Another option for very cold zones is to put heat coils under the beds. These can be heated by either geothermal heat or via a closed loop hot water system fed by a solar hot water heater, wood boiler, or on demand water heater.

Air flow/circulation. Airflow is very important for any greenhouse situation. Air flow is linked to temperature control. When the vents are open, air flow increases. But what happens on colder days when the doors need to be kept closed? Not only do plants need C02 for growth, they need airflow to prevent molds and fungus.

TIP: The biodynamic preparation called 508 can help regulate moisture and keeps fungus down in the soil. It is quite simply Equisetum arvense (field horsetail). This is an ancient plant full of silica. Pick in Spring, dry, add one ounce dried equisetum to four gallons of boiled water. Let this concentration cool then put it in a bucket and let it ferment for a week to four months. Strain off the plant material and store in a glass jar until use.

Pest control. In my experience, the best greenhouses and polytunnels include a pond. This helps with pest control because it provides habitat for predators, e.g. frogs. It also improves the air quality, so may be part of the answer to the previous question.

Because greenhouses and polytunnels are confined spaces, it is possible to turn them into exclusion zones. For example, Alice Gray of Tyddyn Teg, North Wales, has excluded slugs from the farm’s extensive polytunnels. She did this by laying a strip of bran all around the inside edge of each polytunnel. As long as the bran stays dry, slugs are unable to cross it, and as she laid it inside the polytunnels, it does stay dry. Then she applied nematodes within each polytunnel. These ate all the slugs inside the polytunnels, so the polytunnels are more-or-less slug free.​

Irrigation. The main disadvantage of greenhouses and polytunnels is that the rain can’t get in, so plants do need to be watered regularly. Doing this by hand may be time-consuming, but it does mean you get a close look at the plants while you are watering them and may spot problems early, such as pests or mineral deficiencies. However, irrigation systems are very useful, and can be designed to use rain water gathered from the roof of the glasshouse or polytunnel, or can be part of a wider system of channels from a pond or dam. Whether you use overhead sprinklers or soil-level drip feed depends partly on what you are growing: For example, some plants are more vulnerable to moulds if their leaves get wet, especially within a humid glasshouse.

However, you can design your greenhouse so that water flows all through it, and you can direct that flow into other areas too.

This video from Kareen Erbe discusses the use of rainwater in her greenhouse

Soil & Fertility. You can plant your greenhouse plants in pots on the ground, on tables, or on landscape cloth. Or you can just plant directly into the ground. As always, consider your soil’s needs, and make specific choices based on the geography and climate of your area.

Within a rotation system, fertility is managed at least partly by the different needs and gifts of different plant families. For example, the pea and bean family feed the soil via the nitrogen-fixing bacteria in their root nodules. When planting perennials, in particular within the confines of a glasshouse or polytunnel, it is worth putting some thought into this before planting. Do some research into the needs and gifts of different perennials and companion planting. Mulching works well, but remember it may introduce or encourage the pests you have just excluded!

Even/especially if you live in a very cold climate, a greenhouse can be a total game changer, a really nice greenhouse is absolutely worth spending a large amount of money on, even like a year’s salary. if you have savings, this is a wonderful place to put the money. You’ll see why!

And here’s a detailed example of a greenhouse design and build at Loganberry Forest in Australia.

Homework

Questions for Review

1. Where do you have potential for aquaculture, and would the effort be worth the yield? What are the design considerations for a successful integration of an aquaculture on your site? What are the potential problems you can foresee?
2. What are some advantages or disadvantages to season extension in your area?
3. For your region, what would be the benefits of building a greenhouse? What would grow well in a greenhouse in winter in your region? How do you know?
4. In a temperate region, what time of year would you start vegetables to grow through winter? What opportunities are opened up with season extension?

Recommended Hands-On

• Go find an aquaculture system or project near where you live. Make a drawing/diagram of the different elements of the aquaculture and how they interconnect.
• Go find a greenhouse! This could be in your local park or botanic garden, or in a community garden or on a neighbour’s patch. Notice the differences between what is growing inside the green house and what is growing outside.
• Re-visit the greenhouse at different times of the year, and in different weather conditions (e.g. on a warm sunny day and a cold wet day). What changes do you notice, both inside and outside the greenhouse? Talk to the gardener(s) and ask them what they value most about the greenhouse.
• Consider what simple changes you could make in your garden or in a community garden that would create a beneficial microclimate. Try your ideas out! What happens?
• Start collecting items that you can recycle into cloches. Try starting some seeds on a windowsill with and without a small cloche. What difference does it make?
• Make a cold frame! Find an old window (you could ask on freecycle) and make low walls to fit the window. These can be from timber offcuts, old bricks, or for a really cosy cold frame you can use straw bales. Find a stick the right size to prop the window open when you’re working there. And get sowing and planting!
• Include a water feature, appropriate in size for your location, and connect it to the other elements (water flow, waste, human activity, compost, gardens, etc.) in your system.
• Improve your microclimates map by devising as many ways as possible to extend your harvest season.