Gardening With Raised Beds

Gardening With Raised Beds

On this 50th edition of Vermont Home Gardener I would like to announce No Mow May and promote raised bed gardening. There are so many advantages to growing in raised beds that we really should consider them for any garden.  Whether you are beginning a new garden or wish to improve an established garden, raised beds will make your garden more productive, more convenient, and are less work in the long run (no tilling, ever!). Raised beds do very well in the hilly, rocky, weedy, cool, wet, northern New England conditions.  Let’s look at the benefits of delayed mowing and explore a couple ways to build raised beds.

No Mow May is a campaign to support early spring pollinators and amphibians.  As the first pollinators emerge there are limited food sources available and our lawns become a very important source of nectar and pollen, if we will let it happen.  Delayed mowing will allow dandelions to flower along with numerous other small wildflowers (violets, clovers, etc.) that will support pollinators at a critical time.  The added grass height also allows early movement of tree frogs and salamanders without getting chopped up in the grass!  Grass grows fast in May so it might be a challenge to not mow at all but certainly you can raise the mower blades higher (I use 4+ inches) and even establish some May sanctuaries of No Mowing areas in your yard.  Every little bit will help.

Raised Beds.  While building raised beds will require some extra effort in the beginning, they will save you labor later plus all the benefits are well worth the effort.  In case you need convincing, here is a summary of the specific benefits:

  • Deeper soil for better root growth   (bigger, healthier plants)
  • Better drainage in wet, clayey soils
  • Faster soil warming in the spring
  • Efficient use of your planting space   (grow more in limited areas)
  • Reduced soil erosion on slopes
  • Improved soil structure and aeration
  • No need to ever roto-till, dig, or plow the garden   (earthworms do that work)
  • Creates an attractive garden appearance
  • High raised beds are more accessible  (less bending)

Building raised beds is work, but there are several techniques that you can choose from to suit your preferences and circumstances.  Here are a couple.  Since you should never step on the raised beds be sure they are no wider than twice your arm’s reach, usually about 4-5 feet across.  My favorite way to establish a new bed on top of lawn or a field is without any tilling or sod removal.  Simply mow or weed whack the grass or weeds as short as possible (less than 1 inch, if possible) in the area you have designated for your new bed(s).  Cover that shaved ground with corrugated cardboard or 10 layers of newspaper and then spread your compost/soil mixture (50:50) onto the bed.  No side walls are necessary and you should make your bed 6-12 inches deep.  Few weeds can penetrate that paper barrier from below and after they die they will become part of your valuable soil organic matter.  Worms and beneficial microbes will flourish, and the bed will become one with the ground over the first summer after the cardboard or paper has decayed. 

The new raised bed can be planted with seeds or transplants on the same day it is made!  If you’re doing multiple beds leave a walkway space of about 2-3 ft between each bed.  Walkways can be mowed grass or covered with newspaper and wood chips.  Depending on the size of the mature plants, you can plant 1 to 4 rows lengthwise in each bed or you can use the fun Square Foot Garden method to organize your bed.  Remember that you NEVER step on the bed so the soil will remain loose.  No rototilling or digging will be necessary, ever.  Weeds will be more controllable, and the bed only needs added compost annually to keep its depth and fertility.

If your garden area is relatively small or you prefer an organized look then bed walls work well.  You can buy ready made kits for beds from sources like Vermont’s own Gardeners’ Supply that are easy to set up but are expensive.  You can build your own bed walls from lumber, concrete blocks, or stones.  Last year I found a new, ingeniously simple way to anchor the bed corners using concrete corner forms made just for this purpose.  They are solid, stackable, and inexpensive.  Do not use older pressure treated lumber or old railroad ties as the preservatives may leach out into your soil and contaminate your plants and food over time.  Cedar is a very durable wood to use but expensive. Locally available Locust is very good because it lasts longer (5-10 years) while fir and pine are also usable but have a shorter life (3-5 years) in contact with moist soil.  I’ve had success with 2” x 12” locust but 2” x 8” or 2” x 10” will work.  Lumber usually comes in 8 ft lengths so raised beds that are 4 ft wide and 8 ft long or 4 ft wide by 4 ft long eliminate wasted lumber.

Raised beds with 2×12 locust supports.

It’s not necessary to line the beds with a plastic weed barrier but If you have a problem with voles (not moles) you can line the bottom of the bed with ¼ inch wire mesh (“hardware cloth”) folded up and stapled to the wooden sides to keep them from sneaking in from below.  Fill the beds with a 50:50 mixture of topsoil and compost and you’re ready to plant.  There are several good DIY videos and instructions online if you want some building help. 

An alternative approach is to first half-fill the bed boxes (or the open beds described previously) with old rotting logs (that old firewood you never used), branches, and/or wood chips before filling with compost/soil.   This provides bulk to the beds plus a slow release of organic matter and nutrients for several years.  Do not use black locust or black walnut, they are toxic to other plants and decay too slowly.  This technique is originally from Germany and is called “Hugelkultur”. 

What to Plant now?  Dandelion and forsythia blossoms are a signal that it’s warm enough to plant peas, onion sets, carrots, beets, and greens (leaf lettuce, kale, spinach, etc.) outside.  Avoid putting any mulch around your new garden plantings right now as the soil is still cool and still needs more sunshine to warm up.

Protect fruit trees with a first application of Dormant Oil on calm days when the temperature is above 45o F.  As the buds begin to swell it’s time to cover them with this nontoxic oil that will smother over-wintering pests hiding in buds and bark cracks.  After the leaf buds have begun to open in another week or two apply the second oil spray to get pest that are hiding deeper inside the buds and the “crawlers” (larvae) on the stems.  This is effective for apples, pears, peaches, cherries, blueberries, and other woody shrubs.

Looking for more Lawn & Gardening information?  The University of Vermont (UVM) Extension Master Gardeners are available to answer questions from gardeners in Vermont on a broad range of home horticulture topics including soil bed preparation and planting; vegetable and fruit gardening; annuals and perennials; backyard composting; sustainable lawn care; plant diseases and integrated pest management, among others.

Volunteers will answer calls on the Master Gardener Helpline from 9 a.m.-noon, Thursdays through October 27. Call (802) 656-5421.

Questions also may be submitted online at https://go.uvm.edu/gardenquestion for a speedier response. The online form includes an option for providing up to three photos. Gardeners also are encouraged to use the online system to submit photos of plants damaged by insects and diseases.

Soil tests for home gardens are available through the UVM Agricultural and Environmental Testing Lab. For information, visit https://pss.uvm.edu/ag_testing.  If you have follow-up questions about soil recommendations, please upload a copy of your soil test report with the helpline online form.

Do you have a different kind of raised bed?  What experience do you have with raised beds? Please share your thoughts in the comments below.

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