Planning polyhouse farming in Purnia? Purnia is a large city in Purnia district, Bihar, home to about 3.1 lakh people (Census 2011)[1], about 370 km from Kolkata. Below we use the town's monthly temperatures, humidity and rainfall to work out which structure fits, which crops to grow and in which months, before you spend on construction.
Climate for polyhouse farming in Purnia
May is the hottest month in Purnia, with average daily highs of about 38°C. January has the coolest nights, averaging 9°C.[2] The area gets about 1,348 mm of rain a year, most of it in May to September, peaking in July at about 357 mm. Average humidity stays at 75% or more in July to October, which raises the risk of leaf disease and slows evaporative cooling. Purnia sits about 36 m above sea level.[1] On the Köppen–Geiger climate map, Purnia falls in the humid subtropical with dry winters zone (Cwa).[3]
Purnia climate by month
Month
Avg high (°C)
Avg low (°C)
Humidity (%)
Rain (mm)
Jan
23.0
8.6
55
6
Feb
27.9
12.2
44
9
Mar
34.1
17.6
34
20
Apr
38.0
22.9
37
52
May
38.1
25.8
51
122
Jun
36.1
27.1
67
211
Jul
32.2
26.2
84
357
Aug
31.7
25.8
86
253
Sep
30.7
24.6
87
236
Oct
29.6
20.7
80
76
Nov
26.7
15.1
72
4
Dec
23.3
10.3
65
2
Area averages (a grid cell of about 50 km) for 2001–2025, from NASA POWER, centred on Purnia. Rainfall and night temperatures at your plot can differ, especially near hills and the coast.[2]
Advantages of protected cultivation in Purnia
1
Year-round crops
Under cover, chilli pepper can be grown for 10 months a year in Purnia, so you can supply buyers every week instead of one open-field season.
2
Better yield and price
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
Less water
Drip irrigation under cover uses less water than flood irrigation, and the roof keeps July's 357 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 October), so you spray less often.
5
Subsidy eligible
Polyhouse, shade net and nethouse projects in Bihar can apply for Mission for Integrated Development of Horticulture (MIDH) assistance through the state horticulture department.[4]
Which polyhouse suits Purnia?
For polyhouse farming in Purnia, the structure decides which months you can crop and what it costs to run. The heat in Purnia comes with dry air. In April to May, average highs reach 38°C while average humidity is only about 44%. In that dry air, wet pads can bring a 38°C May afternoon down to roughly 32°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 September to November and costs less to run.
Plan for heavy rain in July (about 357 mm): raise the plinth, size the gutters for that month and keep drains away from the nutrient tank. 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 Purnia
Based on Purnia's climate, the crops with the longest growing windows are chilli pepper (10 months), capsicum (9 months) and cucumber (9 months). Chilli pepper fits February to November with Fan & Pad cooling. These are the crops we would plan first for polyhouse farming in Purnia.
Months each crop suits in Purnia
Crop
Naturally ventilated polyhouse
With Fan & Pad cooling
Capsicum
Feb and Sep–Nov
Feb–May and Jul–Nov
Tomato
Feb and Sep–Dec
Feb–Apr and Sep–Dec
Cucumber
Jul–Nov
Mar–Nov
Chilli pepper
Feb and Jul–Nov
Feb–Nov
Brinjal
Jul–Nov
Mar–Nov
Lettuce
Nov–Feb
Oct–Apr
Broccoli
Dec–Jan
Nov–Feb
Strawberry
Dec–Jan
Nov–Feb
Rose
Feb and Nov–Dec
Feb–Mar and Oct–Dec
Gerbera
Feb and Nov–Dec
Feb–Apr and Oct–Dec
Carnation
Dec–Jan
Nov–Feb
Chrysanthemum
Feb and Nov–Dec
Feb–Mar and Oct–Dec
Anthurium
Oct
Mar–May and Jul–Oct
Orchids
Oct
Mar–May and Jul–Oct
Lilium
Dec–Jan
Nov–Feb
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[5]
370 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.[5] Purnia is large enough for steady local sales to restaurants, hotels and fruit-and-vegetable retailers. Start with a farm size that matches the orders you can confirm.
Polyhouse farming in Purnia with Kryzen
We have built 2 projects in Bihar so far (see our project map (opens in a new tab)). Purnia is about 1,400 km in a straight line from our Chhatrapati Sambhajinagar warehouse, our nearest site.
Towns near Purnia
We also plan and build farms in these towns near Purnia:
Map: LGD 2024 boundaries via bharatlas, CC BY 4.0. For illustration only.
Polyhouse farming in Purnia: FAQs
Can a polyhouse farm run all year in Purnia?
Yes, with the right structure. For Purnia 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 Purnia?
With May highs of about 38°C and 51% 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 Purnia?
Going by the monthly climate, chilli pepper, capsicum and cucumber have the longest growing windows. Confirm prices and volumes with buyers before you plant.
Is polyhouse farming profitable in Purnia?
It can be, if the crop, the structure and the buyers match. In Purnia, chilli pepper and capsicum 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 Purnia?
Yes. Our nearest site is our Chhatrapati Sambhajinagar warehouse, about 1,400 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 Purnia 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.
