As record cold sweeps much of the country, and white-out storms engulf highways, towns and of course our gardens too, there will be many people, when warmer weather returns, looking at collapsed hedges, broken branches, and seeing years of growth destroyed in a matter of hours. Hedges are vital components of many garden landscapes, bringing privacy, reduced noise, extra warmth and creating a calm neutral garden backdrop. When damaged all that is destroyed, and there is no such thing as ‘instant hedge’ to replace it with. Could the damage have been prevented? Can I repair it now? Do I need to plant a new hedge? These are the questions that will be going through everyone’s head as they survey the situation in their garden.

Has the cold killed my hedge?

Consider this – current record-breaking low temperatures are bringing lows from much colder zones than your own ‘normal’ one. If the difference is slight, you will probably only see browning and scorching of foliage. If it is significant, then you could easily see a lot of dead plants, including hedging evergreens, when spring arrives. Since this deep freeze has lasted several days, the low temperatures have had time to ‘bite’ into your plants. While smaller plants below the snow will probably be fine, shrubs, trees and hedges could easily be damaged. If you know what plants your hedge is made off, here are the minimums usually recommended for some of the most common ones, in the Fahrenheit system normally used in America. If your neighborhood experienced temperatures more than 10 degrees below these, then there is a very good chance you will need to replace your hedge come spring – sorry.

• Emerald Green Arborvitae – minus 50 degrees
• Thuja Green Giant – minus 20 degrees
• Leyland Cypress – minus 20 degrees
• Italian Cypress – 0 degrees

If you are replacing a hedge, the question becomes, ‘should I use a hardier plant this time around?’ In the past we would have said, ‘no’, because in most areas a low temperature significantly outside your zone only happens about every 40 years – otherwise you would be in a lower zone, right? But with an increase in extreme weather, probably due to man-made global warming, these events could become more common, as the climate shifts to a new normal. So if you are already at the bottom of the hardiness range for a plant, moving to something a zone or two hardier could be a good idea.

What now? Can I cut it back and re-grow it?

This is a common question when hedges are broken, and if only we could say, “yes”. That of course depends on what plant has been used to make it. Hedges of broad-leaf evergreens, like holly, can be cut back as much as you need, and they will quickly re-sprout, so no problem at all. But most people prefer the smooth surface and easy trimming of conifers – the needle evergreens, especially Arborvitae, Cypress, and of course Thuja Green Giant. These plants cannot re-sprout from older, bare branches – which is why it is best to trim regularly, starting right after planting, and trim little and often. There are just a few evergreens of this type, with yew trees being the most well-known and widely used for hedges, that will re-sprout from older branches. They can be cut right back to a few limbs, and they will quickly regenerate. For the rest the answer is, “No”.

This means that when you are cleaning up your damaged hedge, cut branches back to a side-branch with foliage on it – otherwise you will be looking at that bare stump for a very long time. Even if the result is a very ‘gappy’ hedge, with care, fertilizer and regular trimming, a lot of it may fill in again. Give it a couple of years, and then re-assess.

Can I fill in gaps with young plants?

This is a possible solution when only part of a hedge is damaged, but it can fail, mainly because it is hard for new plants to become established in soil full of the roots of the older plants. There are three things you can do to improve your chances. First, use the biggest plants you can handle. These will have a large root-ball and be able to cope better with the surrounding trees. Secondly, prepare as big a planting hole as possible, removing old roots, and making a good-sized gap for the new plant. You can also put a root barrier on both sides – not all around – to slow the invasion of that nice fresh soil by the older plants in your hedge. Landscape fabric, or barriers for bamboo, are usually available at local garden centers. Finally, be sure to water and fertilize the new plants regularly and thoroughly, for the first two growing seasons, to give them a chance to compete.

Remember when planting to put the stem of the new plant in line with the existing ones, and not, as some people do, with it in front, level with the existing hedge front. If you do that, the new plants will not be able to develop properly, as they will be over-trimmed on one side.

Should I just replant?

In the end, this is often the best advice. Fixing damaged hedges is difficult, unless the damage is minor, and removing the old one and replanting can be easier. It will also liberate a large area of your garden, as old, over-grown hedges – the type most likely to collapse in a snow-storm – are often very wide and steal lots of your garden. Of course, a new hedge will take time to grow, but if you choose fast growing trees like Thuja Green Giant, then the time will soon pass, as with growth-rates of 3 to 5 feet when young – really, this has been demonstrated in trials – you will be looking at a great hedge in just a few years. Remember this time to keep it well-trimmed, and narrow, especially at the top, as wide tops and overgrown hedges are the ones that usually fail.

In recent years there has been a quiet revolution in hedge trimming. Not in the way it is done, but in what tools are used to do it. Commercial landscapers and other gardening professionals were the first to embrace this change, but gardeners are now starting to get on board too, and they are discovering that it is possible to both throw away that noisy, smelly, gasoline-driven trimmer, and forget about that awkward and dangerous trailing cable too. The battery revolution that gave us the cordless phone, then the cordless vacuum cleaner, and dozens of other cordless appliances, has now given us the cordless hedge trimmer – bringing a freedom to trimming that has to be experienced to be believed.

Cordless trimmers have two major advantages over the older choices. First, they are as quiet as any electric trimmer – it is really just the cutting action itself that makes noise, since the electric motor is basically silent – but that trailing cord, and yards and yards of extension are gone. Until you try one it is hard to realize the freedom you have, but trimming suddenly became a whole lot more pleasant. Plus, the elimination of the gasoline engine means not just quiet, but a total lack of fumes, and no gas-cans in the garage either. We are all much more aware of air pollution than we used to be and removing that smelly – and often smoky – machine from your yard is wonderful. Now you can smell the fresh-cut cedar instead of gas fumes.

Like all those other cordless appliances, these newer trimmers are powered by the battery revolution that created the re-chargeable lithium battery. Like all batteries, they can run out of power, and although re-charge times have been reduced hugely, getting the job done can fall apart when the battery runs flat. Make sure the machine you are considering has a lithium battery, and not a cheaper (and inferior) nickel-cadmium one. Lithium charges quicker, and holds far more power, and that is a key consideration. Recent developments have greatly reduced the charging time, with some higher-quality trimmers completely recharging in the time it takes you to make and drink a cup of coffee or eat a quick lunch. That saves you the cost of buying a second battery. Look at the voltage too, a 20-volt battery is minimal, and for more power, and therefore more speed and endurance, consider a 40-volt battery,

How Much Trimming Do I Need to Do?

This is the first question to ask yourself. If you have one large hedge, then how long do you currently take to trim it? If you have planted a new hedge – maybe with Thuja Green Giant – then you might not have much idea, and it depends very much on how tall your hedges are. Also, there is a limit to how long you can work trimming without a break. However a hedge trimmer that runs out of power in less than an hour is only going to be useful for small shrubs around the house, or a short section of boxwood.

Tests of cordless trimmers show that between one and two hours is normal, despite what manufacturers may claim. If you choose a smaller machine, then consider getting a second battery, which will avoid the problem of suddenly running out of power just when you are almost done. Even if you don’t think you will need a second battery, check if you can buy one, as some trimmers don’t offer that, and if the battery fails you will be looking at buying a whole new trimmer.

How Long Do I Need to Spend Trimming?

As a home gardener you probably won’t need more than a couple of hours, and remember too that there is only so long you can hold a 10-pound machine in the air. Most better-quality cordless trimmers will last between one and two hours before needing charging, which will probably be sufficient for a session – keep it turned off when you are moving around, putting up or taking down ladders, etc., and only run it while you are actually trimming. If you want more time, or those commercial landscapers reading, there are two options that will help you keep going longer. Move to a backpack battery – which is also a good option if you find the weight of a trimmer with its battery a bit much – as these have much longer run-times, or secondly, invest in a STIHL trimmer. This company pioneered battery-powered garden equipment, and their tools have outstanding battery life – the AP300 36-volt battery is good for about 5 hours of steady running.

How Often Do I Trim?

This might seem like an odd question, but it relates to a major limitation with trimmers, which is the thickness of branches they will cut through. If you don’t trim often, or just have an informal screen you cut back every couple of years, then you will need a trimmer that can cut through ¾-inch material. There are two things to look at here. Look at the absolute width of the guide spaces – obviously you can only cut what will fit into the guide – and secondly, how quickly will it cut through that branch. There is a surprising degree of variation in this test, but generally a more powerful machine will obviously cut faster. If you trim infrequently, then you should consider a more powerful machine, and avoid the frustration of jamming branches, or resorting to loppers to get the job done. If you are a frequent trimmer, then you will be cutting thinner and softer material, so this issue is going to be less important to you.

How Tall and Wide is My Hedge?

When putting in a hedge, and deciding on its height, always go for the minimum. It becomes exponentially more difficult to cut hedges as they increase in height and being able to trim from the ground is so much faster than using ladders. The length of the cutting bar, and the availability of extension pieces, are big factors to consider if you have taller hedges. Some extensions can cut at 90^o, which means you can trim the top from the ground. Cutting bars vary in length, and between 16 and 20 inches is a good all-round length to go for. Shorter blades are perfect for smaller bushes, and longer ones – they go up to 40 inches – are a good choice if you have a large hedge.

What is My Budget?

Obviously this is important to us all. Expect to pay about $100 for a basic, lower-power trimmer, and over $200 for something more durable and substantial. Commercial-grade equipment will run much higher, but using it is over-kill for most home gardeners.

Winter is a difficult time in the garden, especially if you live in colder regions, although even in warmer areas sudden cold snaps can wreak havoc, as happened in the South recently. Snow, cold winds, and in warmer areas periods of dryness, can all damage hedges and destroy the careful work and nurturing of years. So taking preventative steps is always a worthwhile investment of time, and with just a little effort and attention we can make the difference between a hedge that comes through winter looking perfect, and one that needs lots of attention and time to come back again.

Tips for Winter Care of Hedges and Evergreens

• Keep the soil moist, by watering through fall, and during winter dry spells
• Protect the foliage, especially with new hedges, by using an anti-desiccant spray
• Keep salt at bay, with screening placed away from the hedge, not right on it
• Use a high-potash fertilizer, this element protects from dryness by thickening the cell walls

Water Your Hedge in Winter

In every region, watering is the single best thing you can do for your hedge. In cold areas, where the ground freezes for periods of time, and even all winter long, evergreen plants find it difficult to draw up water from the frozen ground – imagine drinking a glass of frozen water. This means that the foliage, which is still losing water to the atmosphere, especially when dry or cold winds blow, can desiccate and become dried out. This may not be noticeable until spring, when new growth should begin, and instead the warmer days complete the drying process of these already-dead branches. This effect, called ‘winter burn’, is seen not only on hedges but on other evergreens as well, so while watering your hedge, water your specimen evergreens too.

Watering helps because if the ground is very moist it takes more cold input to freeze it, and some un-frozen water will remain available to your trees. Since the foliage will survive best if it is fully plumped-up with water when the ground freezes, you should begin this winter watering in late fall, and continue until the ground freezes. Especially with younger, newer hedges and evergreens, mulch over the soil will also help, not just to conserve the moisture you have added, but to keep the soil warmer and reduce the intensity of freezing.

In warmer areas watering issues can also arise, as long dry stretches are common in winter, and just because the temperatures are lower doesn’t mean the ground is not drying out. It is easy to be caught unawares when cold sunny days draw lots of moisture from evergreen foliage, and directly from the ground. Check around the base of your hedges and evergreens weekly, and if the soil seems dry, give it all a good soaking.

Speaking of soaking, it is also important to water correctly. Standing for a few minutes with a hose spraying is unlikely to be very effective, since you want the water to penetrate deeply into the soil, not just dampen the surface. A slow-running hose pipe, or a soaker hose of some type, will be far more effective in re-filling the deeper water reservoirs in your soil. When putting in a hedge it makes lots of sense to install a simple watering system at the same time, which can even be connected to a timer. You don’t need a full-scale irrigation system – just a trickle hose or ‘leaky pipe’

In colder areas you probably won’t need to water during winter, but watch out when early spring arrives, as then too the soil can dry rapidly as the temperatures rise, especially if it has been a dry winter. Remember to keep checking until your full spring and summer schedule becomes established.

Use Anti-Desiccant Sprays

It is surprising that these sprays, used by professionals for decades, are not used much more by gardeners. Perhaps it is the distrust of spraying, but in fact these materials are all-natural, and so they are completely safe to use. They contain an ingredient called ‘pinene’, which is extracted from pine trees cut for lumber. When mixed with water this material forms a giant network of molecules that becomes a water-proof film across the foliage it is sprayed on. It is this coating that greatly reduces water loss from the foliage, and that makes it so useful. On evergreens in winter, especially if you have planted them recently, it can make an enormous difference, keeping them green and healthy even in difficult and exposed locations. Spray shortly before the ground freezes, and if there are periods above freezing during the winter, especially if it rains, then try to get out and re-spray, as heavy rain will weaken or remove the coating. It is basically invisible once applied, so it is much more attractive, and more effective too, than the old-fashioned burlap wrapping still seen in some colder areas.

Protect your plants from salt spray and runoff

Salt is the enemy of plants. It sucks moisture out of the foliage, and out of the roots too if it enters the soil. Luckily its use is declining, and there are better alternatives for your driveway, especially if you have a hedge alongside it. You can’t control what your city puts down though, so if you have hedges along the roadside, you can easily have them severely damaged by salt drift blown up by traffic or high winds. The best protection is to catch it before it lands on your plants, and the simplest method is to put up a burlap screen, placed a foot or so in front of the hedge, and a little taller. This will trap the salty spray and hold it away from the foliage. A common mistake is to hang the burlap right on the hedge, but if you think about it for a moment, by doing that you are holding a wet, salty cloth against the leaves, which is at least as damaging as doing nothing at all. That gap is important, so make sure you create it when putting up your screening.

Use High-potash Fertilizer in Fall

You won’t see it labelled with that name, but if you read the label you will see a relatively high number at the end of that formula of three numbers showing the composition. These fertilizers are often sold as ‘fall-fertilizer’ for evergreens, and their secret ingredient is the element potassium, often called potash. This is held in the plant sap and causes the cells to take up extra water. Not only does this protect against drying out, it stimulates the cell walls to thicken, so that water is lost more slowly through them. As well, the extra elements in the sap makes it less likely to freeze. Together, all these effects reduce the risk of winter damage to the foliage. Although not really a winter tip, as it should have been done already, it is something to think about for next fall, to give your evergreens the protection they need.