GRAVEL BED PLANTS

 A gravel bed is an irrigated, raised garden bed filled with washed pea gravel. It is a method to heel-in bareroot plants to make them available for fall planting. It is a low-risk, low-maintenance holding site to offer more flexibility around bareroot planting timeframes.  

There are many good reasons to want one, and one of the biggest is that it cultivates bareroot plants’ roots in a way that makes them available for fall planting projects. Typical bareroot plants are not available until the winter, so this technique offers more flexibility for when to plant. Other reasons are that plants can be stored without cold storage, it conserves water, and no weeding necessary. 

Larger plants need more space than smaller plants. For larger plants, I recommend 25 plants per 4 square feet, and smaller plants at 25 plants per one square foot. 

The most important dimension is the depth. The depth should be 1.5 feet, and the perimeter dimensions can be anything that you want them to be. 

Small plants = (Length’ x Width’) * 25

Large plants = (Length' x Width’) * 12.5

The gravel bed can be constructed out of any materials that are on hand. I have seen wading pools, wooden framed raised beds, galvanized stock tanks, and jersey barriers used to contain the pea gravel. Use anything that has drainage and achieves a 1.5’ depth.

Yards of pea gravel needed = (Length’ x Width’ x Depth’ of gravel bed)/27’

Example: 12 yards pea gravel = (12’ x 18’ x1.5’)/27’

Washed pea gravel has rounded edges which prevents cutting off roots when the plants are harvested from the bed. Also, the pea gravel doesn’t compress which maintains large pore spaces between the stones. Large pore spaces facilitate fibrous root development.

Irrigation demands change with the seasons. Spring and fall need less water than summer. Peak summer should receive about 100 minutes of water per day, and spring and summer should receive 50 minutes of water per day. Starting in September, reduce watering as much as possible to prepare the plants for dormancy.

Spring and fall require less water than the summer because it is cooler and there is less daylight. In the spring a fall, water for fifteen minutes every six hours. In the summer, water for fifteen minutes every four hours. After Sept. 15, water as little as possible. 

Dig down to your first knuckles. If you feel wet, cool stones and see dark, glistening stones, you have the right amount of water. If the stones feel warm and dry and they are light colored, then add water. 

It is difficult to overwater them. The pea gravel is incredibly well drained so long as there are adequate drainage holes in the bottom of your frame.

Yes. I found that the plants use 1/10th of a gallon of water per day. 

 Install the plants in early Spring from late- March to early April. 

The longer the plants are in the gravel bed the more time there is to develop a fibrous root system. Six to eight months is a good amount of time to achieve that. 

I use a few digging forks to loosen up the pea gravel from around the roots and pry the plants out of the gravel. Shovels can sever the roots and nullify the root volume gains that happened throughout the year.  

Immediately after harvest, store the plants in a seedling bag, keep the roots moist, and keep them in a cool, dark place. Refrigeration below 40 degrees and above freezing is best.  

Plant them as soon as possible. They are not dormant, and they still have leaves. They should be in storage for less than a week.  

Bigleaf Maple (Acer macrophyllum), Black Cottonwood (Populus balsamifera ssp. trichocarpa), Black Hawthorn (Crataegus douglasii), Douglas Spirea (Spiraea douglasii), Mock Orange (Philadelphus lewisii), Oregon Ash (Fraxinus latifolia), Osoberry (Oemleria cerasiformis), Pacific Crabapple (Malus fusca), Pacific Ninebark (Physocarpus capitatus), Red Osier Dogwood (Cornus sericea), Salmonberry (Rubus spectabilis), Snowberry (Symphoricarpos albus), Thimbleberry (Rubus parviflorus), Twinberry (Lonicera involucrata), Vine Maple (Acer circinatum), Water Birch (Betula occidentalis). 

Please also see the Plant Profiles Sheets below. 

Conifers don’t like the gravel bed.  

The plants do not need fertilizer. Fertilizers leach out of the system quickly, and most of the fertilizer will be out of the growing zone before the plants use it.  

There are common pests that will be found in the gravel bed. You will find fungal diseases like powdery mildew, rust, and apple scab.  

Consult the Pacific Northwest Pest Management Handbook for up-to-date information.