Plantskydd vs Liquid Fence: blood or egg for deer

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Side by side

Plantskydd vs Liquid Fence at a glance

Unlike Bobbex vs Liquid Fence, this is a genuine difference in chemistry. Plantskydd is dried blood; Liquid Fence is rotting egg and garlic. That changes how long each lasts, when each is most useful, and how well they work together.

In the three-year trial summarized by University of Maryland Extension, plants treated with Liquid Fence averaged 20% browse loss and plants treated with Plantskydd 26%, against 49% for untreated plants. Bobbex, included here as a third option, averaged 17%. All three worked; none came close to zero, and no single product won every year.

Our take: these two are not really competitors. Plantskydd is the better winter product and Liquid Fence the more convenient growing-season product, and rotating them gives deer two unrelated smells to deal with.

Dried blood vs putrescent egg and garlic

Plantskydd is made from dried blood with a vegetable-oil sticker that helps it adhere, per the Plantskydd label. UMD Extension classifies its active ingredient as blood protein with an odor mode of action. Deer read the smell as a sign of predators or death and avoid the area, which is why it is often called a fear-based repellent.

Liquid Fence uses putrescent whole egg solids and garlic, per its product page. The egg gives off a sulfurous smell and the residue tastes bad, so it works on both odor and taste. Per Penn State Extension, repellents that rely on taste must be applied directly to the plant.

Both chemistries fall into the category that has tested best. The USDA National Wildlife Research Center work summarized in the Forest Service Forest Nursery Notes found that repellents giving off sulfurous odors, such as egg and blood products, generally outperformed taste-only products.

How long each lasts, and what rain does

Plantskydd's main selling point is longevity. The manufacturer's FAQ claims up to six months of protection on dormant plants in winter, with shorter intervals during the growing season when new leaves keep appearing. That claim comes from the manufacturer, not from an independent trial, but the logic holds: a dormant yew or arborvitae is not growing new, untreated tissue, so one good coat can last.

Liquid Fence's label is built for the growing season: weekly applications for the first month, then monthly. It is labeled rain-resistant once dry.

The independent data is more conservative than either label. Per UMD Extension, egg- and blood-based products last roughly one to three months or more, and at the highest-pressure sites repellents held damage in check for six to eight weeks in many cases, with 10 to 12 weeks common where pressure was lower. Plan around those numbers, and treat the six-month claim as a best case on fully dormant plants.

Both products are sold as rain-resistant once dry, and the key words are once dry. Spray on a dry day with no rain forecast for several hours. Per Penn State Extension, repellents work best applied on dry days when temperatures are above freezing, which also matters for winter applications of Plantskydd.

After a heavy storm, or a long stretch of rain, check whether the residue is still visible and reapply if it has washed off. The same goes for plants under overhead sprinklers.

Smell and organic listing

Neither is pleasant to apply. Plantskydd smells of blood and Liquid Fence of rotten egg and garlic. Both companies say the odor fades for people once dry while deer continue to detect it. Spray away from doors, windows and seating areas, and pick a day when you will not be outside much.

Plantskydd is OMRI Listed, which matters for certified organic growers and anyone who wants inputs that meet organic standards. We did not find an OMRI listing for Liquid Fence's deer and rabbit spray in our research. If organic status matters to you, check the current label and the OMRI products list before buying.

Powder, liquid or granular

Plantskydd comes as a soluble powder concentrate, a ready-to-use liquid and a granular shaker. Liquid Fence comes as ready-to-use, concentrate, a hose-end ready-to-spray bottle and granules. How you plan to apply it should drive the format.

• Plantskydd powder is the economical choice for many evergreens, but the UMD researchers found it difficult and time consuming to mix and keep in suspension, and it tended to clog the sprayer. Shake often and use a sprayer you can clean easily.
• Plantskydd ready-to-use liquid avoids the mixing problem and is the simplest way to treat a few shrubs in winter.
• Liquid Fence ready-to-use and hose-end bottles make the frequent growing-season sprays quick, which matters when you are re-treating weekly in the first month.
• Granular products from either brand go on the ground around plants. They are area treatments and work alongside, not instead of, spraying the foliage deer eat.

On cost, the UMD data put Plantskydd concentrate at roughly twice Liquid Fence concentrate per gallon. Plantskydd's longer winter interval narrows that gap if you are spraying fewer times.

Winter application tips

Winter is when Plantskydd earns its place, and when deer damage on evergreens is often worst because other food is scarce.

• Spray before browsing starts. Per UMD Extension, apply before the first sign of damage so deer do not establish a feeding pattern. In the Northeast that usually means late fall.
• Pick a dry, above-freezing day. Penn State Extension says repellents work best applied in the dormant season on dry days when temperatures are above freezing, so the spray can dry on the needles and bark.
• Cover everything deer can reach, including the tips of branches and the sides facing paths and woods.
• Check after thaws and storms. Freeze-thaw cycles and heavy rain can wear any coating down. Reapply where residue is gone.
• If you use Liquid Fence in winter, follow its label's temperature and timing directions; its monthly schedule means more trips outside than Plantskydd's claimed winter interval.

Use on edibles

The label is the law. Use either product only on the plants and in the ways the label on your container allows.

Per Penn State Extension, most commercial deer repellents are not labeled for use on edible plants, with a few exceptions. An OMRI listing means a product is allowed in organic production; it does not by itself mean you can spray it on lettuce you will pick tomorrow. Our practical rule: keep spray off the parts of fruits and vegetables you eat unless your label explicitly says otherwise, and keep pets and children off treated plants until they dry. For vegetable gardens with steady deer traffic, a deer fence is usually the better answer.

What university trials say about repellents in general

Set expectations before buying either one. The research consistently shows that repellents reduce damage rather than prevent it:

• Maryland: in the UMD Extension trial, repellent-treated plants averaged 18% browse loss across all products versus 49% untreated, at sites with very high deer density. Only 27 of 140 treated plants (19%) lost more than 35% of their foliage, compared with 21 of 28 untreated plants (75%). UMD recommends changing repellents with each application because deer get used to them.
• Connecticut: Ward and Williams of the Connecticut Agricultural Experiment Station tested commercial repellents on Japanese yews; their study, summarized by Conservation Evidence, is one of the main independent sources on how well these products hold up in the Northeast.
• Penn State: Penn State Extension advises applying in the dormant season on dry, above-freezing days and notes that taste repellents must go directly on the plant.
• Rutgers: the Rutgers deer-resistance ratings are a reminder that for plants rated frequently severely damaged, repellents alone often are not enough in high-pressure areas.

Which to pick, and when

• Late fall through winter: Plantskydd. Coat yews, arborvitae, rhododendrons and young trees before deer shift to woody browse, and enjoy the longest interval between sprays.
• Spring and summer: Liquid Fence. Its weekly-then-monthly schedule lines up with flushes of new growth on hostas, daylilies and tulips.
• All year: rotate them. Because the chemistries are unrelated, alternating Plantskydd and Liquid Fence follows UMD's advice to change repellents with each application better than pairing Liquid Fence with Bobbex.
• Strict organic: Plantskydd, for its OMRI listing.
• Heavy pressure on favorite plants: add a fence or switch to deer-resistant perennials.

Common mistakes

• Expecting six months in summer. Plantskydd's longest claims apply to dormant plants. Growing plants make new, untreated leaves, so re-treat as they grow.
• Sticking with one product. Deer get used to a familiar smell. Alternate blood and egg products.
• Starting after damage. A deer that has already been eating a plant is harder to discourage than one that never started.
• Spraying on wet or frozen foliage. Neither product sticks well if it cannot dry.
• Relying on spray alone where pressure is extreme. If plants rated frequently damaged are being stripped every week, repellents will slow the losses, not stop them.

How we choose

This page is research-based. We did not conduct our own repellent trial, and nothing here describes personal results. Our editor, Thomas Joseph, gardens in zone 7a on Long Island, but the comparisons draw on published sources: the University of Maryland Extension three-year repellent trial, Penn State Extension and Rutgers NJAES guidance, Connecticut Agricultural Experiment Station research, USDA work summarized by the Forest Service, and current manufacturer labels and FAQs. Manufacturer claims such as Plantskydd's winter longevity are labeled as manufacturer claims. Independent trial data outranks marketing in our verdicts.

Frequently asked

Is Plantskydd better than Liquid Fence?

Not across the board. Liquid Fence had a slightly better three-year average in the University of Maryland trial (20% vs 26% browse loss), while Plantskydd claims much longer protection on dormant plants in winter. They work best rotated.

How long does Plantskydd last?

The manufacturer claims up to six months on dormant plants in winter and shorter during active growth. UMD Extension puts egg- and blood-based repellents at roughly one to three months or more, depending on deer pressure.

Is Plantskydd organic?

Plantskydd is OMRI Listed for organic production. An organic listing does not override the label, so follow its directions on where it can be used.

Plantskydd vs Bobbex: which is better?

In the UMD trial Bobbex averaged 17% browse loss and Plantskydd 26%, but Bobbex was reapplied every 10 to 14 days. Bobbex suits the growing season; Plantskydd suits winter and long intervals.

Can I alternate Plantskydd and Liquid Fence?

Yes, and it is a good pairing because blood and egg are unrelated smells. UMD Extension recommends changing repellents with each application so deer do not get used to one.

Does Plantskydd work in the rain?

It is sold as rain-resistant once dry. Apply on a dry, above-freezing day with no rain expected for several hours, and reapply if heavy rain has washed off the residue.

Sources

1. Using Commercial Deer Repellents to Manage Deer Browsing in the Landscape (FS810-A), University of Maryland Extension
2. Orchard Wildlife: Integrated Management of White-Tailed Deer, Penn State Extension
3. Landscape Plants Rated by Deer Resistance, Rutgers NJAES
4. Effectiveness of deer repellents in Connecticut (Ward and Williams, Human–Wildlife Interactions), Conservation Evidence
5. Effectiveness of commercially available deer repellents, USDA Forest Service, Forest Nursery Notes
6. Frequently Asked Questions about Plantskydd, Plantskydd
7. Plantskydd Animal Repellent Ready To Use label, WSU PICOL label database
8. Deer & Rabbit Repellent Ready-To-Use, Liquid Fence

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