Top 10 Mistakes by Coastal Gardeners

I love plants-- and truly enjoy working with my clients to fully appreciate the plants in their gardens.

Frequently, I am asked by concerned homeowners the same questions about their landscapes.  So I figured it might be useful to make a list of what this professional landscape gardener would advise clients NOT to do in their coastal gardens, and avoid common pitfalls.

10.  Planting shrubs or trees because they are cheap or familiar, without any research on coastal conditions.  A common mistake: new coastal residents may think, well it's still Oregon, still the same zone, and I like this or that plant.  Why not grow it here?  The Willamette Valley, where most new residents come from, provides ideal growing conditions for a vast array of nursery plants-- the coast has a much smaller palette from which to draw.  Wind, salt, sandy soil, heavy winter rainfall and a much milder growing season (insufficient heat for many plants) are among the reasons.  Please visit with a quality coastal nursery and spend a little time talking with the knowledgeable staff, before you design and plant your garden.

9.  Failing to provide for torrential rain (drainage) in winter.  This might seem obvious but it really gets overlooked when people design the new house and yard, or purchase an existing one.  Really take the time to figure out where the water from your downspouts will end up, and where it comes rushing down your street, and talk to neighbors about any problems with storm drains, etc.  Many times when we see a tree or shrub mysteriously die in someone's landscape, we dig it up and lo, the hole is filled with water.  Drainage!

8.  Failing to provide wind shelter (from the north and west) in summer.  Coastal homeowners often realize there are strong winds in winter with the dramatic storms, but fail to account for the persistent dry winds that occur in summer.  These are mostly from the north, more often than directly from the ocean (west), and usually the cause of brown leaves and dieback on the north side of plants.  Often the solution is a simple windscreen (made from shadecloth) for the first couple years until plants are established. Related to this problem is inadequate summer water.  If you want to grow a good-looking lawn, it will unfortunately require lots of summer water.  Shrubs are less needy but need water if they are exposed to ocean winds.

7.  Choosing to grow mostly lawn on the lakefront or oceanfront.  Following on the last item... lawns are cheap and easy to install, but we all know they cost plenty to maintain.  If you are willing to do all the mowing, there are still the costs of water, fertilizer, weed control, lime, moss killer, and repair/fuel for the mower.  While you ponder those costs, allow me to point out the cost to our watersheds.  Runoff from fertilizers and the destruction of useful habitat for wildlife are just two of many reasons that lawns are bad for lakes and oceans.  If you are lucky enough to own waterfront property, please consider reducing your lawn.

6.  Using "quick-green-up" fertilizer, or that containing phosporus, on any waterfront property.  If you are still set on the necessity of that waterfront lawn, choose your fertilizer carefully.  Common lawn fertilizers contain very high percentages of nitrogen that is immediately released when wet.  The fast "green-up" results from that sudden injection of nitrogen to the grass plants.  But grass like any plant, can only use so much nitrogen at any one time, and the excess is leached into the soil and our watersheds.  Excess nitrogen levels, along with phosphorus, contribute to problems like growth of algae and "dead zones" in the ocean.  Instead, choose fertilizer (preferably organic) with low nitrogen percentages, and check the label to see that part of it is slow-release.  This means it's not all flushed into the soil at once.  Phosphorus is unnecessary to grow a healthy lawn and detrimental to lakes; it's already been banned in Minnesota in lawn fertilizer.

5.  Shearing every last shrub into geometric shapes instead of skillful pruning.  Take the time to learn about your trees and shrubs, how they bloom and grow naturally.  Or hire someone who knows, not just how to wield a hedge trimmer.  A few plants sheared is fine-- but really, do we have to torture them all?

4.  Resorting to repeated heavy use of herbicides or pre-emergents to control weeds.  If we are weeding then we aren't doing our job very well.  Weeds can almost always be prevented with careful attention and light maintenance, or caught at a very early stage.  Simply patrolling your landscape with a good sharp hoe once or twice a month will catch them small.  Mulch will prevent most of them if it's refreshed on a regular (annual) basis.  Planting close together will reduce large areas for weeds to get started. Cutting your lawn at a taller height will shade out many new weeds. By the time you get out the herbicides or pre-emergent chemicals, you are just treating a symptom.

3.  Excavating valuable topsoil during construction and failing to replace it before planting.  It's a common practice for builders to remove topsoil when building a new home.  This gets the structure onto more stable mineral-based subsoil instead of the topsoil that is filled with organic matter.  But subsoil is lousy for plants!  A responsible builder will stockpile the topsoil and bring back a decent planting depth so you can start your landscape.  In my opinion at least 6" should be expected, and more is better.  If you are stuck with a final grade that is done with mostly subsoil, you have work to do.  Amending large areas before planting a shrub, amending several inches before growing a lawn, adding compost and mulch over many years.  It's a big job to try and re-create what nature did over hundreds of years.

2.  Cutting down trees or foliage on the ocean bluff.  When development was going like crazy on the coast, those oceanfront lots became wildly expensive.  As a result, homes built on the bluffs were going to maximize every legal square foot they could build on, and creating "open views."  Unfortunately many folks have learned the hard way that vegetation is the only thing holding that bluff together, and protecting the soil from wind/rain erosion in winter storms.  Trees and shrubs on the ocean bluff will also provide helpful wind screening from strong ocean storms, and make your yard and deck more habitable.

1.  Topping any tree to provide for better ocean views.  Lately there has been some debate in our town about a local tree ordinance designed to protect and preserve our city's trees.  One of the original requirements was a ban on topping trees.  Unfortunately our city leaders received a lot of negative feedback to the effect that they were preventing "pruning."  Folks, topping is not pruning.  Topping is cutting off the leader of a large-maturing tree.  It causes decay to enter through that cut (which does not heal) and creates unstable, new "tops" out of side branches that try to fill the leader void.  These branches are weakly attached and become hazards, and the tree is never the same.  Instead, thin out some interior branches to allow for a view through the trees, or as a last resort, replace the tree with one that doesn't grow as tall.  There are many options of tall shrubs and small trees to choose from, ask your power company for a list.

Planning Your Coastal Landscape

So you have moved to the Oregon coast or bought a summer house here-- by this I mean the real coast, by the ocean. Folks in the eastern parts of Washington and Oregon frequently refer to anything west of the Cascade mountains as "the coast." But conditions are radically different in the Willamette Valley than here on the actual coast-- and here is where guidance is lacking for the aspiring gardener.

Before you run to the local nursery, or worse yet, bring plants with you from the valley, you will want to spend some time assessing your site.  I like to think of our neighborhoods in "zones," albeit not the USDA-type temperature zones.  This has more to do with exposure to the ocean.

In the winter, we receive very strong winds mostly from the southwest, often extremely cold and pouring rain at the same time.  Sure the whole northwest is rainy, but we receive more water than most other locations, especially near the headlands or by the foothills of the Coast range.  The winter storms hit these barriers first, and dump a ton of moisture all at once.  Wind is frequently in the 50+ mph range, and bad storms have brought us 80-100 mph winds.   And yes, it does freeze here.  Not as often as inland, but we get snow and freezing temps on occasion.

Summer is mostly comprised of dry weather (believe it or not) for months, with strong persistent winds from the north and fog laden with saltwater when the valley gets hot.  Hence you might start the day with clear weather, and by noon the "marine layer" (fog) will have covered your coastal neighborhood.  The deposit of salt on plants along with little moisture to wash it off or flush it through the soil, combined with drying winds, can be lethal for plants.

A new coastal gardener might then just want to throw up their hands in dismay.  What will possibly survive all these challenges?  Many plants grow exceptionally well here, but it's important to figure out what coastal-zone you are in.  

If you are oceanfront, subject to the full force of winds and receiving plenty of salt-spray, your choices are pretty narrow.  If you are a block or two back from the ocean, your choices widen considerably but realistically you should exclude some plants you might wish for.  If you are some distance away, like "no way can I see the ocean from my house"-- you may be able to grow all kinds of climate-adapted plants, even vegetables.

Some good tactics to begin: go on walks of your neighborhood, and take notes or pictures.  I like digital pictures, that way I can remember the plant I liked and also the setting in which it can grow.  One almost-oceanfront place we cared for included a mature fig tree-- which likely would not have survived were it not for the shelter and warmth of 5-foot stucco walls on three sides of the tree (west-facing).  Not only did it survive but produced a bounty of figs every year.  

After you have toured the neighborhood, seek out a quality local nursery and bring your pictures or notes.  The whole point of going to a good nursery, as opposed to a supermarket that sells plants in the spring,  is to utilize the knowledge of the great people who work there.  In a coastal nursery, the first question you will be asked is "how close are you to the ocean?"  They don't want to sell you something that dies in a month, and they have plenty of experience with trial and error of all different plants in varied locations.

If you are close to the ocean, make note of any windscreens that might have been planted or built by the smart people who sold you the house, or the lack thereof.  A nice big shore-pine on the southwest corner might obstruct a little of your view, but will provide needed shelter from winter winds if you are planting nearby.  If you need to add wind shelter to your yard, consider that a permeable screen that allows wind to pass through somewhat will do a much better job than a solid one-- if the wind can't get through, it will swirl around the barrier and the result is more increased velocity when it gets to the plants.  Yikes.

Be honest with yourself-- especially if this home is not your primary one.  How often will you be here to visit?  What time of year?  Do you really want to pull weeds and prune things when you are on vacation?  How will the plants get watered in the dry season?  If you want a lush landscape and don't plan on doing the work, consider hiring a year-round garden service.  They can also let you know when a tree has fallen after a windstorm and you might want to fix that roof.  If you want to plant in summer, there must be a way to provide water to new plants.  Just because it rains here in winter, don't assume things will be fine without water in summer.  Drip on a timer system, or hire it out, but if you don't plan for this you can say goodbye to new plants.

Time of year that you visit might give you clues: if in spring/early summer, you might enjoy lots of rhodies and azaleas, with spring bulbs.  If in mid-summer, hydrangeas, daylilies and beach roses will be in bloom along with many perennials and annual flowers.  Fall will see the ornamental grasses send up their lovely seed-stalks and the tall sedums like 'Autumn Joy' display soft-pink flowers, to grace the few deciduous plants like vine maple whose leaves turn.

Finally, take some time to visit a mature public garden like the Connie Hansen Garden in Lincoln City.  A place like this, carefully tended by volunteers and developed by an expert botanist, will provide you with equal parts information and inspiration.  If you visit at different times of year you may discover new plants that never came to mind, and make new gardening friends in the bargain.  

Next up:  preparing your coastal garden for spring