Planning polyhouse farming in Siwan? Siwan is a mid-sized city in Siwan district, Bihar, home to about 1.4 lakh people (GeoNames)[1][2], about 570 km from Kolkata. This guide works from Siwan's own monthly climate to suggest the protected structure, the crops to start with, and the months each crop is likely to do well.
Climate for polyhouse farming in Siwan
May is the hottest month in Siwan, with average daily highs of about 42°C. January has the coolest nights, averaging 8°C.[3] The area gets about 1,011 mm of rain a year, most of it in June to September, peaking in July at about 290 mm. Average humidity stays at 75% or more in July to September, which raises the risk of leaf disease and slows evaporative cooling. Siwan sits about 77 m above sea level.[2] On the Köppen–Geiger climate map, Siwan falls in the humid subtropical with dry winters zone (Cwa).[4]
Siwan climate by month
Month
Avg high (°C)
Avg low (°C)
Humidity (%)
Rain (mm)
Jan
22.9
7.9
50
11
Feb
28.0
11.6
43
14
Mar
34.7
17.3
31
10
Apr
40.3
23.7
25
16
May
41.8
27.7
33
52
Jun
39.8
29.5
49
155
Jul
33.9
26.9
77
290
Aug
32.5
26.0
83
234
Sep
31.4
24.5
84
179
Oct
30.6
20.2
73
46
Nov
27.3
14.3
62
1
Dec
23.4
9.4
56
3
Area averages (a grid cell of about 50 km) for 2001–2025, from NASA POWER, centred on Siwan. Rainfall and night temperatures at your plot can differ, especially near hills and the coast.[3]
Advantages of protected cultivation in Siwan
1
ವರ್ಷವಿಡೀ ಬೆಳೆಗಳು
A polyhouse stretches the season: in Siwan cucumber can be grown for about 9 months a year under cover, longer than in the open field.
2
ಉತ್ತಮ ಇಳುವರಿ ಮತ್ತು ಬೆಲೆ
Plants grow without rain, hail and wind damage, so yields are higher and more even, and clean, graded produce sells at a better price, especially off-season.
3
ಕಡಿಮೆ ನೀರು
Drip irrigation under cover uses less water than flood irrigation, and the roof keeps July's 290 mm of rain off the crop and the soil.
4
Less pesticides
Insect net on vents and doors keeps out most pests, and controlled ventilation helps with leaf disease in the humid months (July to September), so you spray less often.
5
ಸಬ್ಸಿಡಿಗೆ ಅರ್ಹ
Polyhouse, shade net and nethouse projects in Bihar can apply for Mission for Integrated Development of Horticulture (MIDH) assistance through the state horticulture department.[5]
Which polyhouse suits Siwan?
For polyhouse farming in Siwan, the structure decides which months you can crop and what it costs to run. The heat in Siwan comes with dry air. In April to June, average highs reach 42°C while average humidity is only about 36%. In that dry air, wet pads can bring a 42°C May afternoon down to roughly 31°C inside a Fan & Pad polyhouse, which keeps herbs and vine crops going; lettuce will still struggle in the hottest weeks. For vine crops such as capsicum and cucumber, a naturally ventilated polyhouse with a shade screen works from February and October to November and costs less to run.
Plan for heavy rain in July (about 290 mm): raise the plinth, size the gutters for that month and keep drains away from the nutrient tank. Sunlight peaks in April at about 6.4 kWh per m² a day, so add a shade screen for leafy greens in the brightest months. A nethouse, the lowest-cost option, can grow hardy crops in February and October to November, when it is mild and fairly dry.
Crops for Siwan
Based on Siwan's climate, the crops with the longest growing windows are cucumber (9 months), chilli pepper (8 months) and capsicum (7 months). Cucumber fits March to November with Fan & Pad cooling. These are the crops we would plan first for polyhouse farming in Siwan.
Months each crop suits in Siwan
ಬೆಳೆ
ನೈಸರ್ಗಿಕ ವಾತಾಯನದ ಪಾಲಿಹೌಸ್
With Fan & Pad cooling
ಕ್ಯಾಪ್ಸಿಕಂ
Feb and Oct–Nov
Feb–Apr and Aug–Nov
ಟೊಮೆಟೊ
Feb and Oct–Nov
Feb–Apr and Sep–Nov
ಸೌತೆಕಾಯಿ
Jul–Nov
Mar–Nov
Chilli pepper
Feb and Aug–Nov
Feb–Apr and Jul–Nov
ಬದನೆ
Aug–Nov
Mar–Apr and Jul–Nov
ಲೆಟ್ಯೂಸ್
Nov–Feb
Oct–Apr
ಬ್ರೊಕೊಲಿ
Dec–Jan
Nov–Mar
ಸ್ಟ್ರಾಬೆರಿ
Dec–Jan
Nov–Feb
ಗುಲಾಬಿ
Feb and Nov
Feb–Mar and Oct–Nov
ಜರ್ಬೆರಾ
Feb and Nov
Feb–Mar and Oct–Nov
ಕಾರ್ನೇಷನ್
Dec–Jan
Nov–Mar
ಸೇವಂತಿಗೆ
Feb and Nov
Feb–Mar and Oct–Nov
ಆಂಥೂರಿಯಂ
Difficult
Mar–Apr and Jul–Oct
ಆರ್ಕಿಡ್ಗಳು
Difficult
Mar–Apr and Jul–Oct
ಲಿಲಿಯಂ
Dec–Jan
Nov–Mar
Kryzen planning estimate from the monthly averages above and each crop's usual day and night temperature range. Variety, soil or substrate temperature and shading change the result, so confirm with a trial.
₹5,165Spending per person per month, urban Bihar, 2023–24[6]
570 kmto Kolkata, the nearest metro (straight line)
Urban households in Bihar spent an average of ₹5,165 per person per month in 2023–24, below the all-India urban average of ₹7,078.[6] Local demand in Siwan may be small for exotic greens, so plan where the rest of the harvest goes.
Polyhouse farming in Siwan with Kryzen
We have built 2 projects in Bihar so far (see our project map (ಹೊಸ ಟ್ಯಾಬ್ನಲ್ಲಿ ತೆರೆಯುತ್ತದೆ)). Siwan is about 1,160 km in a straight line from our Chhatrapati Sambhajinagar warehouse, our nearest site.
Towns near Siwan
We also plan and build farms in these towns near Siwan:
Map: LGD 2024 boundaries via bharatlas, CC BY 4.0. For illustration only.
Polyhouse farming in Siwan: FAQs
Can a polyhouse farm run all year in Siwan?
Yes, with the right structure. For Siwan we would plan a Fan & Pad polyhouse for leafy greens. Even then, lettuce is hard to grow in May to September, so plan another crop for those months.
Which polyhouse is best for Siwan?
With May highs of about 42°C and 33% average humidity in that month, we would start with a Fan & Pad polyhouse for leafy greens.
Which crops should I grow in a polyhouse in Siwan?
Going by the monthly climate, cucumber, chilli pepper and capsicum have the longest growing windows. Confirm prices and volumes with buyers before you plant.
Is polyhouse farming profitable in Siwan?
It can be, if the crop, the structure and the buyers match. In Siwan, cucumber and chilli pepper have the longest seasons under cover. Confirm prices and volumes with buyers first; our Detailed Project Report works out the cost, yield and returns for your plot.
Does Kryzen build polyhouses in Siwan?
Yes. Our nearest site is our Chhatrapati Sambhajinagar warehouse, about 1,160 km away, and we have built 2 projects in Bihar.
Is there a subsidy for polyhouse or hydroponic farms in Bihar?
Yes. Protected cultivation projects in Bihar can apply for Mission for Integrated Development of Horticulture (MIDH) assistance through the state horticulture department. Check the current rate and area limit when you apply.
Discuss your Siwan farm project
Share your plot location, water test and crop targets. We will suggest the right structure and growing system, and send an itemised quotation.
A computer engineer turned hydroponic farmer from a multigenerational farming family in Satara. Sudhir founded Kryzen in 2019, and the team has since built 350+ protected and hydroponic farms across India.
