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Nighttime humidity is not a problem that needs to be vented away

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Night hours present a persistent and costly challenge for commercial greenhouse operators. When the thermal screens are closed and the ventilations are closed, the greenhouse is closed, trapping the moisture produced by the crop. This creates a high-stakes battle against condensation, disease and unnecessary energy loss. Amir Kandlik, B.Sc. Plant Science and Genetics in Agriculture and agronomist with Drygair explores the critical problem of nighttime humidity and explains the strategic shift from traditional ventilation-based control to a system built around active indoor dehumidification. “This ‘closed greenhouse’ approach improves energy efficiency and supports stronger crop health.”

© Drygair

Night challenge: Thermodynamic and pathological risk
“At night, plants continue to transpire even though photosynthesis has stopped. Without the drying effect of daytime conditions, the air mass in the greenhouse quickly approaches saturation,” says Amir. “Traditional methods rely on ventilation, but ventilation replaces warm, CO₂-rich air with cold outside air. This increases heating demand, destabilizes temperatures and can introduce more moisture, especially in humid weather.”

A variation of this, heating the air before it is vented, wastes energy because the air conditioner is blown out immediately. “In cold, rainy, or snowy conditions, ventilation becomes impossible and humidity increases unchecked. As relative humidity rises above 85 percent and temperatures drop, surface temperatures can drop below the dew point. Condensation then forms on leaves, fruit, and structural elements, creating conditions that promote Botrytis, powdery mildew, and powdery mildew.”

Solution: “Closed” paradigm with active dehumidification.
A more advanced strategy replaces night ventilation with active internal dehumidification, keeping the greenhouse closed. Amir explains that it starts when the unit pulls in moist air, cools it below its dew point and condenses the water vapor into liquid form. “The latent heat released by condensation is captured and recycled, heating the dry air before redistributing it throughout the cottage. Instead of losing heat to dryness, this method converts moisture into heat and creates a net positive energy cycle.”

© Drygair

Basic advantages of the closed night strategy
This approach improves disease prevention by maintaining a stable vapor pressure deficit and preventing dew formation. Keeping surfaces above the dew point significantly reduces disease pressure. Flower tests recorded a 98% reduction in Botrytis when relative humidity remained below 85%. Energy efficiency is also increased because the airfields remain closed and latent heat is recovered during dehumidification. Vegetable producers have reported energy savings of 50%.

“Climate uniformity is improved as constant air circulation removes microclimates, and sealed conditions store CO₂ for uptake at dawn,” says Amir. Crop quality and yield benefit from consistent transpiration and improved movement of nutrients and calcium. Basil had a 15 percent yield increase without downy mildew, and unheated tomato houses had a 25 percent higher yield per stem.

Practical settings for leaders
Adopting this strategy requires changing the operational logic, which is usually handled by a climate computer. “During the day, the vents are open and the natural ventilation manages the humidity, so the dehumidifiers are turned off. At night, when the outside temperature drops below the indoor set point, the vents and screens close, and the dehumidifier operates at an RH of about 75 to 80 percent. The priority is to maintain a dew point range of at least 2 degrees. While heating is used only for temperature stability, nighttime temperatures stay below 10 degrees Celsius. in regions with , an additional defrost coil is required for continuous operation.

Looking at the field results
Field studies show that flowers grown according to this strategy maintained lower relative humidity, achieved significant energy savings and did not require night ventilation. Basil trials showed a 15 percent increase in yield and zero downy mildew. Tomatoes and peppers have seen a 5 to 25 percent increase in yield and a 98 percent reduction in disease. Cannabis growers recorded 30 to 40 percent higher yields with about 50 percent energy savings.

Specific questions about geography and climate
In very cold climates, this view is especially good. Ventilating at minus 10 degrees Celsius creates an extreme heating load, and sealing the greenhouse and dehumidifying the interior retains heat, recovers latent heat and reduces boiler use. In hot and humid climates, night ventilation is unreliable during warm or rainy weather. Active dehumidification removes moisture in a controlled manner, and with additional Air-Water Heat Exchange, the system can heat or cool the air through an external water loop.

Supporting scientific and technical references
Research includes Elad and Shtienberg’s work on Botrytis cinerea, University of Massachusetts Extension greenhouse moisture reduction guidance, Stanghellini’s transpiration studies, and Ho and Adams’ work on water and nutrient uptake in tomatoes.

Without ventilation
“Nighttime humidity is not a problem to be banished, but an imbalance to be managed,” says Amir. “The closed greenhouse strategy treats moisture as an energy resource instead of a waste product. By keeping greenhouses closed at night and using active internal dehumidification, growers can reduce disease, improve energy efficiency, retain CO₂, stabilize the nighttime climate, and increase yield and crop quality. This is one of the most impactful changes in modern greenhouse climate management.”

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Custom Cones USA launches Cones Canada

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Custom Cones USA has announced the launch of Cones Canada, a wholly Canadian operation designed to meet the growing needs of Canadian pre-roll producers, processors and brands.

With a stocked warehouse in Ontario and a dedicated Canadian e-commerce platform, Cones Canada eliminates the complication that Canadian businesses have historically faced in sourcing pre-rolled cones: no import fees, no customs delays and no currency conversion headaches. Orders are billed in Canadian dollars (CAD) and shipped from Ontario to anywhere in Canada.

Why Cones Canada, why now?
The legal cannabis market in Canada continues to grow, and pre-rolls are a $1.4 billion market. In 2024, pre-rolls passed as the top category in the country, and retained their title in 2025 with 77.2 million units sold, again the highest of any category, according to cannabis analytics firm Headset.

Canadian growers and processors have long relied on Custom Cones USA’s reputation for quality. Its cones have been tested to Health Canada standards for flowers and are trusted by leading pre-roll manufacturers worldwide. However, cross-border orders came with additional cost, time and logistical complexity.

“We’ve been supplying Canadian cannabis brands for years, and the demand from our Canadian customers made this next step an easy decision,” said Harrison Bard, co-founder and CEO of Custom Cones USA. “With Cones Canada, we’re bringing the same products, the same quality standards, and the same expert support that our customers have always trusted. Only now we’re doing it without limits.”

Cones Canada’s Ontario facility carries four of the most popular pre-rolled cone sizes from the Custom Cones USA catalog, each in two types of European-sourced paper: Refined White and Natural Brown.

In addition to ready-to-ship bulk cones, Cones Canada offers access to Custom Cones USA’s machine, packaging and custom branding options, including full-color filter tip printing, cigar bands and outer wraps. and custom packaging, Canadian brands can build a distinctive, shelf-ready product line backed by Pre-Roll Experts.

For more information:
Cones Canada
conescanada.ca/

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TSA Clarifies That Its Marijuana Policy ‘Has Not Changed’ Despite Clickbait Headlines

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Over the past week, many news organizations have been running exaggerated headlines about a supposed change by the federal government to allow marijuana to be brought into airports and airplanes.

But it’s not true, the Transportation Security Administration (TSA) tells Marihuana Momenti.

“TSA’s policy on medical marijuana has not changed,” a TSA spokeswoman said in an email Wednesday.

“According to the TSA website: If any illegal substance or evidence of criminal activity is found during the security screening, TSA will refer the matter to law enforcement,” they said.

While it’s true that the agency’s list of medical marijuana “What can I bring?” section of its website was updated on April 27, there were no major changes in policy.

Currently, the website says “Yes,” passengers can carry medical marijuana in both the cabin and checked bags, with special instructions.

But TSA Cannabis Policy Says “Yes” to Medical Marijuanawith the same caveats, since 2019.

both current The version of the page was updated last month and archived The version from seven years ago reads:

“TSA’s screening procedures are security-based and designed to detect potential threats to the aircraft and passengers. Accordingly, TSA security officers do not search for illegal drugs, but if a security screening detects illegal substances or evidence of criminal activity, TSA will refer the matter to a law enforcement officer.”

The previous version also had this language regarding federally legal hemp products, but it has now been removed in the latest update:

“Under federal law, possession of certain marijuana and cannabis-infused products, including certain Cannabidiol (CBD) oils, is illegal. TSA officers must report any suspected violation of the law, including possession of certain marijuana and cannabis-infused products.

Products/medicines containing CBD derived from hemp or approved by the FDA are legal as long as they are produced within the regulations set forth by law under the Agricultural Improvement Act of 2018.

Many news organizations that haven’t bothered to compare the current version of the TSA page to the previous one seem to think so The Trump administration’s move to federally regulate cannabis last month it caused the air travel safety agency to make a change in its policy, but that is not the case.

“Website updates occur periodically for clarity and accuracy,” said the TSA’s email to Marijuana Moment on Wednesday. “TSA policy remains the same. No changes have been made.”

Other agencies, meanwhile, have made cannabis policy changes consistent with federal rescheduling.

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has published a Draft update to a gun purchase form to recognize the legal status of medical marijuana in the reprogramming. The revised section of the question states that only the “recreational use or possession of marijuana” is federally prohibited, omitting the prior form’s mention of medical cannabis.

The US Treasury and Internal Revenue Service (IRS) said they plan to issued new tax guidelines for the marijuana industry after reprogramming. The reform will benefit state-licensed marijuana businesses by allowing them to take federal tax deductions that are currently prohibited under IRS Code Section III, known as Section 280E.

Even the Drug Enforcement Administration (DEA), which has long opposed the legalization of cannabis and accused the Biden administration of stalling the initiative in the reorganization process, has done so. It launched a registration process for legal marijuana businesses in the state to take advantage of the federal benefits that come with the reform.

The Department of Transport, however, clarified this last week Truck drivers, airline pilots and other federally regulated safety-sensitive workers still cannot use medical marijuana without being punished

The TSA, for its part, posted a marijuana-infused claim to celebrate National Brownie Day Back in 2020.

“We hear it’s National Brownie Day, so we’re here to talk about something really sticky-icky-icky (ooh wee),” the federal agency posted on its Instagram account. “Hopefully this isn’t posted near 4:20 because we’re going down.”

That high-flying introduction was followed by a sort of public service announcement, warning passengers not to bring cannabis through airports.

“Marijuana, humble or neat, is not dope in your cabin or checked bag,” the message reads, setting up a rhyming scheme and immediately dropping: “This includes cannabis products and CBD oil, which are illegal under federal law, except for products that contain no more than 0.3% THC or are approved @F dry weight.”

The hashtags included in the post include “#NationalBrownieDay,” “USAtraveling,” “#leaveitathome,” “#chronnic” (misspelled) and “#maryj.”

Image courtesy of Steve Fitzgerald.

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Medical cannabis cultivation event set for June 8 in the Netherlands, ahead of GreenTech

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On June 8, researchers, growers and technology providers from around the world will gather in the Netherlands for a day of presentations, facility tours and networking focused on the cultivation of medicinal cannabis, organized by the Dutch cannabis consortium Cultivation for Compounds and MCPIR.

© Andrea Di Pastena | MMJDaily.com

The event takes place across two locations. The morning program takes place at the MCPIR in Bleiswijk, where Jaime Ahumada and René Corsten, cannabis researchers and consultants at Delphy, will present their latest findings on mother plant management, clear strategy and upcoming research plans at the Delphy Improvement Center, including opportunities for growers to actively participate in ongoing research and knowledge development. Attendees can also take a tour of the cannabis cells.

In the afternoon he will visit the World Horti Center in Naaldwijk with presentations from Mexx Holweg, Dutch Light Innovations and Cultivation for Compounds, followed by a visit to Vertify.

MMJDaily covered last year’s event on the ground. Check out our photo report to see the research sites and the community gathered there.

For more information:
MCPIR
www.mcpir.nl
worldhorticenter.nl/eu/themes/cultivation-for-compounds/

Delphi



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