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Simply Gardening
by Doug Green
Bogged Down... and Loving It!
Part 1

There is an entire class of plants that many gardeners ignore in the garden. Or worse, if they try to grow them, they fail miserably. In the next few articles, I’m going to give you some tips and tricks for growing perennial plants that like to keep their feet wet. And, if you’ve ever seen a full-blooming stand of Japanese Iris or Primula, you know why I’d want to grow these garden gems.

To begin with, we need a way to hold moisture in the soil. Unfortunately, it is normally not enough to simply add peat moss to the soil in hopes it will hold enough moisture. These plants generally want more than that. In our own gardens, we excavate down at least 18 inches and put a layer of heavy plastic down. The plastic is laid at least half way up the sides of the excavation so we have a good 8 to 12 inches of water holding capacity. I don’t worry about bringing the plastic right up to ground level although if your soil is quite sandy, it might be a good idea.

The garden soil is returned to the hole but all rocks and weed roots are removed while backfilling. Rocks and plastic liners simply don’t co-exist. I never really worried about having the odd hole in the plastic liner as this is a wet garden not a swimming pool. If the water drains away, then it is really easy to turn on the sprinkler and wet it all back up again. The design for this summer’s project includes putting two sprinkler heads in this garden area so that when the regular garden gets one dose of water, the wet-plant area will receive a double dose.

Water is certainly something you want to pay particular attention to when it comes to wet-plant gardening.

You’ll have to keep the area topped up with water throughout the heat of the summer. So do plan on having a tap nearby or at the very least, a long hose that will reach the garden so you can put it on trickle and leave it to soak. Do not build it where you can not supply it with the water it needs. This kind of garden is perfect for placement under the downspouts of eavestroughs. I do note that you’ll need some form of water breaker on the downspout or you’ll quickly carve a canyon trench in the peat soil.

The garden can be as large or small as you desire. My biggest to date was 6 feet wide and about 45 feet long although I confess I’m winding up for a larger one this summer. My smallest was simply a peat moss bale, set on edge and buried into the garden. The top was cut off the bale once it was buried to give me a tiny garden that was 2 feet long, 1 foot wide and 2 feet deep.

You see, acid soils are the second thing that these wet-plants tend to like. I’ve found that growing in straight peat moss grows great plants and tend to be quite liberal with the peat when constructing any outdoor wet-plant garden bed. The big bed above was completely filled with peat, there was no soil added at all. The bed for this summer is being designed to have approximately 30 to 50% peat and the rest will be good topsoil. Specialty plants in this new garden (those that like even more acidity) will be grown in sunken tubs in the garden and the soil will be 100% peat.

Getting all this peat wet is a chore for Job. You need that kind of patience because peat is slow to wet. Turn on the tap and walk away from a large peat bed. Once it starts floating, turn off the tap and wait 24 hours. Mix it up or turn over the soil in the bed and repeat the hosing. Keep wetting down the soil until it is completely wet from top to bottom. This process took over a week in my large garden and I mixed the soil up between each soaking.

It takes longer than you think to soak peat moss completely. I know this year I am planning on leaving a week between the construction of the new bed and installing the plants. I’ll water twice a day and when I think the bed is wet (usually after 2 to 3 days), I’ll leave it for another few days just to allow each individual peat fibre to soak up water. These extra few days make the difference between initial plant success and failure.

I do add compost to the soil mix. The more the merrier. It is neutral so it does not change the acidity but it does provide all the nutrients these plants desire. You’ll find that regular chemical fertilizers with their high Nitrogen counts will overfeed and cause the peat moss to degrade too quickly. Overfed plants look good initially but then they get floppy and weak. Weak plants are prone to disease and insect attacks. Also remember that most wet-area plants are quite happy being fed on the poor side, they do not need excessive amounts of fertilize to give good blooms.

The second reason I add compost and a few shovels of soil is because I want the micro-organisms that live in acidic soils to get established and start creating a good soil ecology. A good soil ecology will do more in the long run to create a great garden than any amount of fertilizer will ever accomplish. So, go natural on this garden folks, both your plants and your garden will thank you for it.

Next week, we’ll get to the plants that live in damp soils.

Get your gardening questions answered at the Simple Gifts Farm web site... or click here to write to Doug Green!

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