You invest in premium bird seed to attract a colorful variety of wild birds, only to watch a squirrel empty your feeder in minutes. That expensive seed is wasted, and your frustration grows. Fortunately, modern squirrel proof bird feeders are designed to protect your investment while providing a reliable dining spot for cardinals, finches, chickadees, and more. In this guide, we evaluate the best squirrel proof bird feeder for expensive bird seed, focusing on models that use weight-activated mechanisms, durable materials, and smart designs to keep squirrels at bay. Whether you are new to backyard birding or a seasoned enthusiast, these feeders will save your seed and your sanity. For more context, see our complete collection of best squirrel proof bird feeders.

1
Best Seller

WLNYUGS Squirrel Proof Bird Feeder

WLNYUGS
9.9 /10
SPS
Backyard Feeder Guide Squirrel-Proof Score (SPS): scored from squirrel-proofing design, setup compatibility, durability and materials, ease of installation, and value for price. Commissions do not affect scores. See how we score at /how-we-review/.
The WLNYUGS squirrel proof bird feeder uses a weight activated gravity spring to close feeding ports when squirrels land, while finches, cardinals, and chickadees can feed freely. With a chew proof metal build, rain shield, and easy maintenance, it is a reliable choice for backyard bird watchers who want less seed waste and squirrel damage.
Pros & Cons

Pros

  • Gravity activated spring closes ports under squirrel weight, preserving seed for smaller birds
  • Four curved perch ports attract cardinals, finches, chickadees, and other wild birds
  • Chew proof metal construction and reinforced hanging ring resist outdoor wear
  • Rain shield roof protects seeds from moisture and reduces spoilage
  • Detachable design and 3 pound seed capacity make cleaning and refilling easy

Cons

  • The 14 inch height and hanging mount require a sturdy branch or hook to stay stable in strong wind.
  • Persistent squirrels may still try to break in, and no squirrel proof feeder is completely foolproof.
  • The clear plastic seed tube needs regular cleaning to keep the seed level visible and the feeder looking neat.
Detailed Review

The WLNYUGS squirrel proof bird feeder is a four port hanging feeder designed for backyard bird watchers who want to keep squirrels from stealing seed. It is best suited for gardens, yards, patios, and porches where finches, cardinals, chickadees, and other small wild birds visit regularly. The weight activated spring mechanism automatically closes the feeding ports when a squirrel lands, but allows smaller birds to feed normally.

The gravity spring system is the standout feature. When a squirrel applies weight to the feeder, the ports close to block access, while normal sized backyard birds can still reach the seed. The four curved perches give multiple birds room to eat, and the improved structure helps reduce seed spillage. This creates a cleaner feeding area and makes daily bird watching more enjoyable.

This feeder is built with sturdy metal materials, an upgraded metal hanging ring, and a rain shield roof. The reinforced ring resists chewing and adds stability in windy conditions, while the rain shield keeps seeds dry during wet weather. The detachable design and large 3 pound transparent seed tube make refilling and cleaning straightforward, which is important for maintaining a healthy feeding space.

Because the feeder is 14 inches tall, it needs a strong hook or branch to hang securely. As with any squirrel resistant feeder, determined squirrels may still attempt to reach the seed, so occasional monitoring is wise. The clear seed tube can also show smudges from handling and weather, so periodic cleaning will help keep the level visible.

For bird lovers who want a durable, low maintenance feeder that attracts wild birds while reducing squirrel damage, the WLNYUGS squirrel proof bird feeder is a well designed option. It combines a reliable gravity spring, weather resistant build, and easy care features for a hassle free backyard bird watching experience. This feeder also makes a thoughtful gift for parents, grandparents, and anyone who enjoys watching wild birds at home.

Specifications

Brand: WLNYUGS

Product Dimensions: 6 in. L x 6 in. W x 14 in. H

Capacity: 3 pounds

Color: Green

Included Components: Bird Feeder

Mounting Type: Hanging Mount

Recommended Use: Bird watching

Special Feature: Upgraded Metal Hanging Ring Design

2
Editor's Pick

Brome Squirrel Buster Plus Squirrel-proof Bird

Brome
9.8 /10
SPS
Backyard Feeder Guide Squirrel-Proof Score (SPS): scored from squirrel-proofing design, setup compatibility, durability and materials, ease of installation, and value for price. Commissions do not affect scores. See how we score at /how-we-review/.
The Brome Squirrel Buster Plus is a top-rated squirrel-proof bird feeder with a patented shroud that blocks squirrels by weight. It holds 5.1 pounds of seed, features a cardinal ring for large birds, and is built to last. Ideal for bird lovers tired of squirrels stealing seed.
Pros & Cons

Pros

  • Truly squirrel-proof: the shroud closes when a squirrel climbs on, so no seed gets stolen.
  • Durable construction: chew-proof and UV-stabilized plastic stands up to elements and attacks.
  • Lifetime limited warranty shows confidence in the product and long-term value.
  • Large seed capacity means you refill less often, saving time and effort.
  • Adjustable weight setting lets you customize which birds can access the feeder.

Cons

  • Pole adapter is sold separately, so you need to buy it to mount on a pole.
  • Hanging hook is not included; you may need to order a separate hook for hanging from a tree branch.
  • Heavy birds like doves are excluded by the design, which might disappoint some birders.
Detailed Review

The Brome Squirrel Buster Plus is the ultimate solution for bird enthusiasts who are tired of squirrels raiding their feeders. This deluxe model holds 5.1 pounds of seed and features six feeding ports, plus an innovative Cardinal Ring that welcomes cardinals while keeping out larger, seed-hogging birds. It is designed for anyone who wants to attract a variety of songbirds without the constant battle with squirrels.

The standout feature is the patented squirrel-proof shroud. When a squirrel climbs onto the feeder, its weight forces the shroud down, closing off access to the ports. This mechanism is both effective and humane, as the squirrel is not harmed but simply denied entry. Real-world reviews from customers who have owned the feeder for years confirm that it truly stops squirrels, even after repeated attempts. The adjustable spring allows you to fine-tune the sensitivity, so smaller birds like chickadees can still feed while larger intruders are blocked.

Build quality is exceptional. The feeder is made from UV-stabilized, chew-proof plastic that resists sun damage and squirrel gnawing. It measures 28 inches tall and has a 2.2-pound weight, making it stable on a pole or hanging mount. The design includes easy-fill top and a base that opens for cleaning. Brome backs the product with a lifetime limited warranty and live phone support, reflecting their commitment to customer satisfaction.

One honest drawback is that the pole adapter is sold separately, so if you plan to mount it on a pole, be sure to order that adapter at the same time. Additionally, no hanging hook is included for tree branch installation, which may require an extra purchase. Also, the feeder is not designed for very large birds like doves or pigeons, so those species will be excluded along with squirrels.

Overall, the Squirrel Buster Plus delivers on its promise. With a stellar 4.7-star rating from over 10,000 reviews, it is a proven performer that pays for itself in saved seed. If you are serious about feeding birds without feeding squirrels, this feeder is a wise investment that will provide years of enjoyment.

3
Limited Time

Brome Squirrel Buster Standard Squirrel-Proof Bird

Brome
9.8 /10
SPS
Backyard Feeder Guide Squirrel-Proof Score (SPS): scored from squirrel-proofing design, setup compatibility, durability and materials, ease of installation, and value for price. Commissions do not affect scores. See how we score at /how-we-review/.
The Brome Squirrel Buster Standard is a durable, weight-sensitive feeder that effectively keeps squirrels away while allowing birds to dine. Ideal for bird lovers seeking a reliable, mess-free solution.
Pros & Cons

Pros

  • Proven squirrel-proof mechanism that works reliably
  • High customer satisfaction with a 4.6 out of 5 star rating
  • Sturdy build quality that withstands outdoor elements
  • Easy to fill and clean, reducing maintenance time
  • Attracts desirable birds while deterring squirrels

Cons

  • Plastic material may not be as chew-resistant as metal alternatives
  • Seed capacity is moderate; may require frequent refills in high-traffic areas
  • Occasional jamming can occur if not cleaned regularly
Detailed Review

The Brome Squirrel Buster Standard is a purpose-built bird feeder designed to eliminate the frustration of squirrels raiding your birdseed. It is ideal for backyard bird enthusiasts who want to feed cardinals, finches, and other small birds without feeding the local squirrel population. With thousands of positive reviews, it is a trusted choice in squirrel-proof feeding.

The standout feature is the weight-sensitive perches. When a squirrel or heavy bird lands, the perches close the seed ports, blocking access. This clever mechanism allows lightweight birds to feed undisturbed. The feeder holds 0.75 quarts of seed, which is enough for moderate traffic, and the transparent reservoir lets you monitor seed levels easily.

Built from durable plastic, the feeder is weather-resistant and designed to last. The four metal perches provide ample seating for birds, and the included hanger makes setup simple. The garden green color blends naturally into outdoor settings. While plastic is lightweight, it may not withstand aggressive squirrel chewing as well as metal alternatives.

One potential drawback is the seed capacity. For high-traffic areas, you may need to refill more often. Also, the mechanism can occasionally jam if seed debris builds up, though regular cleaning prevents this. Overall, the feeder delivers on its promise of squirrel deterrence with minimal maintenance.

Verdict: The Brome Squirrel Buster Standard is an excellent investment for anyone tired of squirrels stealing birdseed. Its smart design and proven performance earn a strong recommendation. Just be prepared for routine cleaning and moderate refill frequency.

4
Top Rated

Brome Squirrel Buster Legacy Squirrel-Proof Bird

Brome
9.8 /10
SPS
Backyard Feeder Guide Squirrel-Proof Score (SPS): scored from squirrel-proofing design, setup compatibility, durability and materials, ease of installation, and value for price. Commissions do not affect scores. See how we score at /how-we-review/.
The Brome Squirrel Buster Legacy is a weight-activated squirrel-proof bird feeder with a patented shroud that closes when squirrels climb on, so the seed stays for the birds. It's durable, easy to clean, and ideal for anyone dealing with persistent squirrels or wasted bird seed.
Pros & Cons

Pros

  • Consistently stops squirrels and saves seed, according to many verified customer reviews.
  • Built with strong, chew-proof materials that survive repeated squirrel attacks and tough outdoor conditions.
  • Easy hand disassembly makes cleaning simple, helping prevent mold, rancid seed, and bird diseases.
  • Adjustable weight mechanism and ventilation keep the feeder flexible and seed fresh.
  • Versatile perches and shroud welcome small perching birds, woodpeckers, nuthatches, and cardinals.

Cons

  • Premium price is higher than many basic feeders, though owners say it pays off in saved seed.
  • No rain shield is included, so wet weather can affect seed if the feeder is not placed under cover.
  • Very large or clever birds like grackles may still find a way to access seed unless the tension is adjusted or the feeder is modified.
Detailed Review

The Brome Squirrel Buster Legacy is a weight-activated, squirrel-proof bird feeder built for backyard birders who are tired of losing seed to squirrels. It suits anyone who wants a durable, low-maintenance feeder that welcomes small perching birds, woodpeckers, nuthatches, and cardinals while keeping oversized pests away.

The patented weight-sensitive shroud drops when a squirrel climbs onto the feeder, closing the seed ports and blocking access without harming the animal. With four metal perches and a 2.6 lb seed capacity, it holds enough sunflower or safflower seed for regular feeding. Customer reviews consistently confirm that squirrels give up quickly once they discover the feeder protects its contents.

Every exposed part uses chew-proof materials, and the feeder can be disassembled by hand for thorough cleaning, which is essential for preventing mold and disease. The seed ventilation system keeps food fresher for longer, and the adjustable spring tension lets you tailor the weight threshold so target birds can feed while heavier intruders trigger the closure. This thoughtful construction earns high marks for durability and ease of use.

The main drawbacks are the premium price and the lack of a rain shield, which some owners add separately. Very determined large birds, such as grackles, may occasionally find a way around the mechanism unless the tension is adjusted or the feeder is modified. These issues are minor for most backyard setups, but worth considering before you buy.

Overall, the Squirrel Buster Legacy is a long-term investment in peaceful bird feeding. It stops squirrels effectively, saves seed, and stands up to tough conditions, making it one of the most reliable squirrel-proof feeders available. If you want a feeder that works from day one and keeps working, this green Legacy model is a smart choice.

5

Wildpark Squirrel Proof Bird Feeder 5LB Metal

Wildpark
9.7 /10
SPS
Backyard Feeder Guide Squirrel-Proof Score (SPS): scored from squirrel-proofing design, setup compatibility, durability and materials, ease of installation, and value for price. Commissions do not affect scores. See how we score at /how-we-review/.
This Wildpark squirrel proof bird feeder combines a sturdy metal build with a 5-pound seed capacity and a triple defense system to deter squirrels. Ideal for bird lovers seeking a durable, large feeder that attracts cardinals, chickadees, and finches while minimizing squirrel access.
Pros & Cons

Pros

  • Durable metal construction with rust resistant finish
  • Large 5lb capacity means less frequent refills
  • Effective triple defense against squirrels (weight activated ports, curved body, strong materials)
  • Clear seed window for easy monitoring
  • Weatherproof roof protects seeds from rain and snow

Cons

  • Not 100% squirrel proof as noted by the manufacturer; persistent squirrels may still find a way
  • Adjustable springs may require some trial and error to set the correct sensitivity
  • Higher price point compared to basic plastic feeders
Detailed Review

The Wildpark Squirrel Proof Bird Feeder is a robust outdoor feeder designed for bird enthusiasts who want to minimize squirrel interference. With a 5-pound seed capacity and a triple defense system, it targets common backyard birds like cardinals, chickadees, and finches. This feeder is ideal for those willing to invest in a durable, metal construction that can withstand harsh weather.

Standout features include the weight activated perches that close feeding ports when a squirrel lands, an inwardly curved body to prevent upside down access, and a rust resistant powder coat. The clear polycarbonate panels offer excellent visibility of seed levels, and the perforated bottom helps keep seeds dry. In real world use, the adjustable spring settings (200g to 350g) allow customization based on local squirrel size.

Build quality is solid: the metal frame feels sturdy, and the roof provides good shelter. The vibrant blue color with dark blue roof adds a cheerful touch to any backyard. However, the feeder is not entirely foolproof against determined squirrels, as the manufacturer honestly states. Some users may need to adjust the spring tension or add extra deterrents.

Potential drawbacks include the learning curve for setting the correct spring sensitivity and the fact that very persistent squirrels might still manage to access seeds. Also, the price is higher than basic plastic feeders, but the metal build justifies the cost for long term use.

Overall, the Wildpark Squirrel Proof Bird Feeder is a well designed, large capacity option for bird lovers who value durability and effective squirrel deterrence. It performs reliably for most situations and is a worthy addition to any backyard feeding station.

6

Brome Squirrel Solution200 Squirrel-Proof Bird

Brome
9.7 /10
SPS
Backyard Feeder Guide Squirrel-Proof Score (SPS): scored from squirrel-proofing design, setup compatibility, durability and materials, ease of installation, and value for price. Commissions do not affect scores. See how we score at /how-we-review/.
The Brome Squirrel Solution200 is a truly squirrel-proof bird feeder with a patented weight-activated shroud that denies access to seed. With six feeding ports, a 3.4-pound capacity, and chew-proof construction, it is ideal for bird lovers tired of wasted seed. Buy it for reliable, long-lasting performance.
Pros & Cons

Pros

  • Effectively stops squirrels from accessing seed without harming them
  • Built to last with chew-proof metal and sturdy plastic
  • Easy to fill, clean, and maintain with tool-free disassembly
  • Attracts a wide variety of birds including cardinals, finches, woodpeckers, and chickadees
  • Secure locking lid prevents clever squirrels from prying it open

Cons

  • Higher upfront cost compared to basic feeders, but pays for itself over time
  • Requires proper placement at least 18 inches from any surface squirrels can use to reach it
  • Seed may get moldy if left low in the feeder during rainy conditions; regular monitoring recommended
Detailed Review

The Brome Squirrel Solution200 is a premium squirrel-proof bird feeder designed for backyard bird enthusiasts who are tired of squirrels stealing seed. With six feeding ports and a 3.4-pound seed capacity, it is ideal for attracting a variety of birds while keeping unwanted visitors at bay. The included seed funnel makes refilling quick and mess-free.

The standout feature is the patented weight-activated shroud: when a squirrel jumps on, the feeding ports automatically close, denying access without harming the animal. Real-world reviews confirm that even the most persistent squirrels give up after repeated attempts. The chew-proof metal components protect against gnawing, and the secure locking lid prevents clever critters from prying it open.

Design and build quality are excellent. The feeder is made from UV-resistant RoxResin and metal, and the tool-free design allows easy disassembly for cleaning. The yellow interior stem provides ventilation to keep seed fresh longer, attracting more birds. Users report seeing goldfinches, chickadees, woodpeckers, and even tanagers visiting regularly.

Potential drawbacks include the higher price point, though many users find it pays for itself through seed savings. The feeder must be hung at least 18 inches from any surface to prevent squirrels from reaching it without triggering the shroud. Additionally, in wet weather, seed near the bottom can become moldy if the feeder is not kept filled or cleaned promptly.

Overall, the Brome Squirrel Solution200 is a top-tier choice for anyone seeking a reliable, durable, and truly squirrel-proof feeder. Its thoughtful design and proven performance make it a worthwhile investment for bird lovers who want to enjoy their backyard birds without the frustration of wasted seed.

7

Droll Yankees Flipper Squirrel Proof Bird Feeder

DrollYankees
9.6 /10
SPS
Backyard Feeder Guide Squirrel-Proof Score (SPS): scored from squirrel-proofing design, setup compatibility, durability and materials, ease of installation, and value for price. Commissions do not affect scores. See how we score at /how-we-review/.
The Droll Yankees Flipper is a motorized, weight-activated squirrel-proof bird feeder that spins to gently deter squirrels while holding 5 lbs of seed. Ideal for bird lovers tired of squirrels stealing seed, it delivers reliable performance with a rechargeable battery.
Pros & Cons

Pros

  • Effectively deters squirrels, chipmunks, and even larger animals like raccoons.
  • Large seed capacity means fewer refills, saving time and effort.
  • Easy to set up and fill; no tools required for assembly.
  • Sturdy build with metal top and base withstands weather and persistent squirrels.
  • Long battery life reported by many users, often lasting months between charges.

Cons

  • Heavy when full (5 lbs of seed plus feeder weight); requires a strong hook or branch.
  • Some users report the plastic tube can develop faint cracks over time, though warranty covers defects.
Detailed Review

The Droll Yankees Flipper is a premium squirrel-proof bird feeder designed for backyard bird enthusiasts who are frustrated by squirrels raiding their seed. It uses a weight-activated spinning perch that humanely flings squirrels off when they land on it, while birds are light enough to feed without triggering the motor. This feeder holds up to 5 pounds of seed, making it ideal for those who want to minimize refills and attract a variety of birds like cardinals, finches, and jays.

The standout feature is the motorized spinning action powered by a rechargeable lithium-ion battery. When a squirrel hops on the perch, the feeder rotates gently, causing the squirrel to lose its grip and fall off. Real-world reviews confirm that this mechanism works consistently, and many users report that squirrels learn to avoid the feeder after a few spins. The battery life is impressive, with some owners going months between charges, though a few have noted it can drain faster in cold weather or with heavy squirrel traffic.

Build quality is excellent, with a heavy-duty metal cap and base, and a clear polycarbonate tube that resists UV damage. The feeder is easy to assemble and fill: just lift the green top, pour in seed, and lock it back in place. The four feeding ports are accessible via a perch ring, and an internal baffle ensures seed flows smoothly to each port. Cleaning is straightforward, though the top does not fully detach, which can make thorough cleaning slightly tricky.

Potential drawbacks include the cost, which is higher than standard feeders, and the need to replace the battery pack every few years (around $50). The feeder is also heavy when full, so it requires a sturdy hanging point. A few users have reported minor cracking in the plastic tube over time, but the lifetime warranty on the body covers such issues. Additionally, larger birds like cardinals may have difficulty gripping the ring perch, though they can still feed from the ports.

Overall, the Droll Yankees Flipper is a worthwhile investment for anyone serious about bird feeding and tired of squirrels dominating their feeder. Its humane, effective design, large capacity, and durable construction make it a top choice. While it has a few minor drawbacks, the enjoyment of watching birds feed without interference far outweighs them. Highly recommended for bird lovers who want a reliable, long-term solution.

Specifications

Brand: Droll Yankees

Model: Yankee Flipper (YF-M)

Capacity: 5 lbs of bird seed

Material: Metal (top and base), Polycarbonate (tube)

Dimensions: 8.5 x 8.5 x 28.5 inches

Weight: 5 lbs (empty)

Power Source: Rechargeable lithium-ion battery (included)

Mounting Type: Hanging (loop bail wire)

Target Species: Cardinals, Chickadees, Finches, Grosbeaks, Jays, Juncos, Nuthatches

Warranty: Lifetime on feeder body, 1 year on motor/battery

Buying Guide for Squirrel Proof Bird Feeders

Weight Sensitivity and Adjustability

The core of a truly squirrel proof feeder is its weight-activated mechanism. When a squirrel lands on the perch or shroud, the feeder closes access to the seed. Look for models with adjustable spring tension so you can fine-tune the sensitivity for your target birds. The Squirrel Buster Plus Squirrel-proof Bird Feeder and Squirrel Buster Legacy Squirrel-Proof Bird Feeder both offer patented weight adjustment, allowing smaller birds like finches to feed while excluding heavier intruders. For a deep dive into this technology, read our guide on best weight-activated squirrel proof feeders.

Build Quality and Chew-Proof Materials

Expensive bird seed deserves a feeder that can withstand persistent squirrel attacks. Chew-proof materials such as powder-coated metal, reinforced polycarbonate, and heavy-duty plastic are essential. The Wildpark Squirrel Proof Bird Feeders for Outdoors uses a robust metal frame with rust-resistant finish, while the Squirrel Proof Bird Feeders for Outdoors from WLNYUGS features a reinforced metal hanging ring. Avoid feeders with exposed plastic parts that squirrels can gnaw through. If you are considering adding a baffle, see our comparison of squirrel proof feeder vs baffle.

Capacity and Ease of Refilling

High-capacity feeders reduce the frequency of refills, which is especially convenient if you use expensive seed blends. The Squirrel Buster Plus Squirrel-proof Bird Feeder holds 5.1 pounds, while the Droll Yankees Squirrel Proof Bird Feeder holds 5 pounds. Both offer easy disassembly for cleaning and refilling. Look for models with tool-free designs, like the Squirrel Solution200 Squirrel-proof Bird Feeder that includes a free seed funnel for mess-free pouring. For tips on proper placement, check our guide on how to hang a bird feeder.

Versatility for Different Bird Species

A great squirrel proof feeder should accommodate a variety of birds, from perching finches to clinging woodpeckers. The Squirrel Buster Legacy Squirrel-Proof Bird Feeder features a shroud that gives clingers a secure surface, while the Squirrel Buster Standard Squirrel-proof Bird offers bottom perches for small birds. The Wildpark Squirrel Proof Bird Feeders for Outdoors has inwardly curved body to prevent squirrels from hanging upside down. For more on choosing the right feeder type, see our article on caged feeders vs baffles.

Final Thoughts

Choosing the best squirrel proof bird feeder for expensive bird seed means balancing sturdy construction, reliable weight activation, and ease of maintenance. For a proven, high-capacity option that handles large flocks and heavy squirrel pressure, we recommend the Squirrel Buster Plus Squirrel-proof Bird Feeder. If you prefer a battery-powered spinning mechanism that startles squirrels without harming them, the Droll Yankees Squirrel Proof Bird Feeder is a clever, entertaining alternative. Both will save your premium seed and keep your backyard birds happy.

Frequently Asked Questions

How do weight-activated squirrel proof feeders work?

These feeders use a spring-loaded shroud or perch that closes the seed ports when a heavy animal like a squirrel lands on it. The mechanism is calibrated to allow smaller birds to feed without triggering the closure. Many models let you adjust the sensitivity to target specific bird weights.

Can squirrels still get into these feeders?

While no feeder is 100% squirrel proof, the best models are designed to defeat even persistent squirrels. The weight-activated closures and chew-proof materials make it extremely difficult for them to access the seed. Some feeders, like the Droll Yankees Flipper, add a spinning motion to deter them.

What types of seed work best with squirrel proof feeders?

Most feeders work well with black oil sunflower seeds, safflower seeds, and mixed seed blends. Avoid using corn or peanuts, which attract squirrels more strongly. The Squirrel Solution200 Squirrel-proof Bird Feeder recommends sunflower seeds, safflower, or dried mealworms for best results.

How do I maintain my squirrel proof feeder?

Regular cleaning every few weeks prevents mold and keeps seed fresh. Look for feeders with tool-free disassembly, such as the Squirrel Buster Legacy, which can be taken apart by hand. Use mild soap and water, rinse thoroughly, and let it dry before refilling. In 2026, many models also feature ventilation systems that prolong seed freshness.