Best Techniques and Equations for Calculating Greenhouse Heat Requirements

Calculating Your Greenhouse’s Heating Requirements

Both for novices and experienced greenhouse gardeners, there is one thing which is a perennial challenge – trying to determine exactly what size of heater is needed to keep a greenhouse at a desired temperature.

Obviously, there are a number of factors involved; the size of your greenhouse will make a difference. The kind of plants you’re growing is also an important consideration. Tomatoes, for instance, will thrive in warmer temperatures than say, lettuce.

One word of caution is in order before we go any further: it can be a bit on the expensive side to heat a greenhouse in the middle of winter, but it’s up to every gardener to decide for themselves what price they’re willing to pay for the pleasure of being able to pick tomatoes or watch tropical flowers bloom in January.

Before you begin to try to calculate how much heat you’ll need to generate, you should also go through your greenhouse carefully to seal any cracks which can allow heat to escape.

You may also want to use a few tricks to help retain heat in your greenhouse, such as large containers of rocks or water; these materials will absorb heat and then radiate it back into the environment, helping to keep your greenhouse a little warmer during the cold months.

The type of heater you use is up to you, but the following should help you begin figuring out your greenhouse’s heating requirements.

First, you’re going to need to take a few measurements. You may already have these figures handy, but if not, you’re going to need to head out to your greenhouse components, with a measuring tape and a stepladder.

You’ll need the following measurements:

1. The length of your greenhouse (L).
2. The width of your greenhouse (W).
3. The height of your greenhouse, measured from the base of the greenhouse to the eaves (H).
4. The height from the floor of your greenhouse to the highest point of your greenhouse’s roof (R).
5. The length of the slope of your greenhouse’s roof (S).

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Just as a note, these figures assume that your greenhouse is a single layer glass or plastic greenhouse whose glazing (or plastic sheeting) runs all the way down to the ground.

• If the glass or plastic doesn't run all the way to ground level and you have brick or other solid materials covering the lower part of the structure, then take measurements of these parts of the greenhouse separately.
• For further references, visit this plastic greenhouse manual by Cornell University Extension.
• You’ll want to halve these measurements when you make your calculations to account for the lower heat loss of these materials.
• If you have a double-layer greenhouse, whether the material is glass or plastic, then reduce the amount of heat you come up with by roughly 30%.

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The figure you’ll arrive at aren't going to be accurate down to the millimeter, but it should be more than accurate enough to assess your greenhouse’s heating needs. This is the basic formula:

First, you’ll need to calculate the total surface area inside of your greenhouse. You can determine this by adding H and S, then multiplying by 2. Now, multiply this figure by L.

Next, add R and H, then multiply by W.

• Add these two figures together to get the total surface area inside of your greenhouse.

If you’re more mathematically inclined, you can make this calculator slightly quicker using this formula: 

[2 x (H + S) x L] +

[(R+H) x W] = Inside Surface Area.

1. The next step is to figure out the difference in temperature between the average winter low temperatures where you live and the minimum temperature you’d like to maintain inside your greenhouse.
2. For instance, let’s say that you’re trying to grow tomatoes in your greenhouse. This means that you’ll want to maintain a temperature of at least 60 degrees.
3. Now, let’s say that your average low temperature in winter is 32 degrees. This is a temperature differential of 28 degrees.

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Now, multiply the temperature differential by the total inside surface area of your greenhouse and you’ll come up with a rough approximate of the number of BTUs you’ll need to keep your greenhouse at your desired minimum temperature.

If you’d rather have this figure in kilowatt hours (what your electric company uses to determine billing), you can divide the BTU figure by 3.413 to arrive at this number.

It’s as simple as that – which is to say, not exactly simple, but if you follow the directions here, you can find out how much heat you’ll need to provide for your greenhouse and a ballpark figure of what it will end up costing to keep your plants thriving in your greenhouse even in the middle of winter.

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25 Tips for Year Round Gardening in Alabama USA

Alabama is a great state for raising a diverse range of plants and flowers. Broken into five distinctive geological regions, you have your choice of planting in the high altitudes of the Talladega Mountains, or the Coastal Plain that covers a large part of the state. Alabama has been rated the fifth richest biological state in the union.

Climate also plays a big part for gardening in Alabama. The northern part of the state has soil similar to the Midwestern states, while the southern portion consists of marshy areas of the Gulf.

Here are 25 tips for year round gardening, regardless of where you live in this great state. Northern Alabama Gardening Advice:

1. March is the time to set out Cabbage, Onions, Lettuce, Broccoli, and Brussel sprouts.

2. Wait until November, before adding more rose bush plants, to your existing flower garden.

3. Camellias, the state flower, grow nicely when planted under those feathery pine trees. The sunshine filters through nicely.

4. Attract butterflies, hummingbirds and Japanese beetles, to your garden, by planting Four o'clock flowers.

5. The perfect flowering shrub for the Piedmont region is the Fothergilla. It loves acidic soil, delivers fragrance, and is very low maintenance.

6. Half-hearty flowers, such as Ageratum, alyssum, Celosia, Phlox, Petunia, Sunflower, Salpiglossis, Thunbergia, are good selections for the northern Piedmont region.

7. There are also tender annuals that do well in well-drained soil such as Godetia, Balsam, Nicotiana, Portulaca, Salvia, Zinnia, Phlox, Periwinkle, Nasturtium, Cockscomb, Begonia, Coleus, Marigold, and impatiens.

8. Creeping violas do not have to be a bad thing. The intoxicating scent can create a haven for your garden. However, you can control the spread with a border of wood chips.

9. Join the MGNA (Master Gardeners of North Alabama), a voluntary group dedicated to bringing education to those interested in the field of horticulture.

Southern Alabama Gardening Tips: 10. Tomatoes and peppers will thrive when set out in March.

11. July is the best time to put those turnips, rutabagas, beans, and peas, in the ground.

12. No green thumb needed for bringing the Louisiana Iris to life, when faced with marshy conditions. They love the natural water found along the American Gulf Coast.

13. Plant bald Cyprus as a lovely backyard landscaping tool for a shaded summer time area and a spectacular hint of sunshine, in the winter, with soft, feathery foliage.

14. Select hardy annuals, such as California poppy, Snapdragon, Calendula, Coreopsis, Candytuft, Gaillardia, Gypsophila, larkspur, poppies, stocks, sweet peas, verbena, dianthus, and pansies to add color to your yard.

15. Fruits and nuts, such as Pecans, Peaches, Pears, apples, plums, apricots, blueberries, raspberries, Gooseberries, blackberries, hickory, walnuts, Dewberries, and strawberries, enjoy the moist, hot climate of southern Alabama. Great Tips for all Alabama Gardening

16. Use red wigglers to make the best vermicompost in Alabama. Use kitchen scraps to feed these hungry friends that can consume half their weight in food each day.

17. Fire ants dislike biodiversity and healthy compost fits this bill, nicely. Spread around the edges of your garden to stop fire ants cold. A little molasses, on top, can further detain.

18. Move your veggies around each year. When their desired spot is found, you will recognize the difference.

19. Avoid fighting Mother Nature. Instead, go with the flow of natural developed wildflowers in your distinct Alabama area.

20. Keep that leftover breakfast coffee and use as a deterrent against slugs and other garden intruders. While caffeine may be a stimulant to humans, it is deadly to creeping predators.

21. Add a backdrop of beauty to your vegetable garden by planting deer-resistant plants, such as Caryopteris, Epdimedium, Goldenrod, and Rosemary.

22. When the pine needles begin to die and pile around your trees, rake them up and use as mulch.

23. Never freak when you see those tiny green snakes. They are around to clean up the insects that prey on your veggies.

24. Get your flower bulbs, plants and bushes, planted in December and January. They will have a head start in the spring.

25. There's a new bug in town, the Megacopta cribraria, or the kudzu bug, is becoming a pest, much like the Asian lady bug. If you see an infestation on your beans, or your house, call your County Extension office for help.

The charming hills, mountains, flat lands, and marshes, can become a haven for many varieties of plants, flowers and food. The climate is especially pleasing for staying active in year round gardening.

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What Beans Grow Well in a Greenhouse?

In the first ever, guest blog post, from the entrepreneur & author Stewart Segura, representing the main sponsor of Just Gardening Fun, the GoGardenGuides brand. Stewart is an executive wholesale accounts manager at EarthCareGreenhouses.

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Intro to Bean Agriculture: By Means of Using Garden Greenhouses

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What Beans Will Grow Well & the Best within a Greenhouse Garden Structure?

Most beans do well in a greenhouse setting, but some are particularly well-suited to it. Asparagus beans prefer steady warm weather that only greenhouses and subtropical climates can provide, so if you live in a continental climate your greenhouse is where you would grow your asparagus beans. For the most tenderness, harvest asparagus beans when they are 12” to 18” long. Fortex beans are similar to asparagus beans in requiring similar growing conditions. Fortex beans can be harvested about 75 days after planting.

Types of Beans That Thrive in a Greenhouse Setting Bronco beans can be harvested around 55 days after planting. Bronco beans also possess the property of being mold-resistant. Louisiana purple pods can be picked about 65 days after planting and have a delicate flavor and an interesting purple color. They are vulnerable to changing environmental conditions, so they grow much better in greenhouses than outside. Runner beans can also be grown in a greenhouse, and it can be useful to do so to avoid cold wintry temperatures. Though with runner beans, it is also important not to let your greenhouse, get too hot in summertime – it may be necessary to provide some shade and ventilation. They also need to be watered often.

Keeping Your Greenhouse Beans Watered You can water greenhouses manually if they are small and few, but if you have large greenhouses or very many of them then this is probably too labor-intensive, and you may want to invest in automatic watering systems like mist sprayers and mechanical evaporation systems guided by time clocks or computers. If you are growing many different plant varieties in greenhouse settings, different watering times and amounts can also get complicated. Using automation can keep these complex schedules under control.

Keeping Your Greenhouse Beans Warm and Cool You also want to keep your beans heated in wintertime – you will need more than just sunlight to keep the greenhouse warm in some locations. There are electric, gas and solar power greenhouse heating systems to help maintain greenhouse temperatures during cold winter nights. Cooling is a concern as well, as bean plants that are too hot on sunny summer days will not grow well. Using shade or evaporative cooling can both be helpful, and proper ventilation is also useful in this respect.

Growing Green Beans in a Greenhouse Environment Standard green beans can also be grown in a greenhouse. They need to be kept warm but not hot in full sun conditions. Green beans also require high quality compost to thrive properly. They should be spaced about 9” apart and supports must be added for climbing purposes – strong, vertical garden twine supported by horizontal wires can be used, and two plants can climb up each stretch of twine. Keep your greenhouse environment somewhat moist for green bean growing to avoid potential red spider mite infestation. Take care that the greenhouse glass is clean as well to allow full sunlight to reach your green bean plants.

Harvesting Greenhouse Grown Green Beans It should take around 75 days for your green beans to be ready for harvesting – check pods daily once they have started to form, since they grow fast. Pick them when they are about 4” long to get the best flavor and texture. Keep picking the pods and more will quickly grow to replace them. Note: Do not leave any on the vine. You can also test pods for eating on another factor separate from their length.  Note: Snap them in half, and if the snap happens cleanly with no string fibers attached, then they are ready to harvest. Also, you will be able to see the beans inside the pods, but they will not be bursting out of the pods. Use scissors to cut the green bean pods from the plants, as pulling them off can risk pulling the whole shallow-rooted plant out of the ground, if you are not extremely careful about it.

What to do with Harvested Beans?  Eat green bean pods, after washing, on the day of picking, or else freeze them. If you do not want the pods and only want the beans, you can let the pods fully ripen – this is the case when the pods are turning brown and starting to split open. When they are ripe, shell the pods and retrieve the beans, which can be eaten fresh, frozen or dried for future use. When green bean plants are finished cropping, they will die and decay. So at this point, cut off the above ground portions of the plants and dispose of them in the form of compost, if you so desire. If you leave the roots to decay in the soil, the soil will be enriched will nitrogen, which can fertilize such crops as cabbages and potatoes.

9 Tips for Successful Container Gardening

There are many ways to use gardening containers.

 

As most people getting into organic gardening soon discover, availability of space is a main concern. Not all of us have acres of back yard.

A great way to solve space constraints is to find creative ways to use gardening containers - pots, metal tubs, window boxes, etc.