Wednesday, December 8, 2010

Don't tell me about bog gardens!

If you have been following along with my garden adventures you will have noticed that I have referred a few times to our water woes on this 5 acre parcel of land, only half jokingly called The Swamp. I can appreciate that many of you will have dismissed my mutterings as being an over-reaction. “Why don’t you just plant water loving plants” I hear you say. “Embrace the land – make a feature out of it” or even “How romantic – your own stream”. Bah humbug is my reply.
Kayaking anyone?

Water  POURING out from beneath the house

The problem you see lies in the definition of ‘too much’. The resident frogs and I have agreed that the wetland meadow is theirs and we have even re-opened an original watercourse so that we do indeed have a seasonal stream in one area. The problems remain though that   
  1. We need to kayak to the barn in winter.
  2. I have the only swim-thru greenhouse in the Pacific Northwest.
  3. The sump pump goes 24/7 (for those if you in drier regions I should explain that sump pumps are used to remove water from underneath houses built in damp areas), and
  4. We have more mosquitoes in spring than the tropical swamps of Africa. 
Get the drift? Then there’s the small detail that I am determined to create a showcase mixed border in an area close to the house which was underwater for most of last winter and I do NOT want a 100’ x 50’ bog garden!

So what do I do? Clearly we are well beyond the ‘right plant, right place’ philosophy and need to tackle drainage problems caused by solid clay over glacial till and a number of underground springs, which in one area appear to be just 4’ below ground. Here’s what we’re doing.
  • The first problem was that the downspouts were just pouring water onto the ground rather than into a drain system and the sump pump while removing water from underneath the house was fighting a losing battle since the water was just recycling back down again. These problems were relatively easy to address by digging trenches and installing drainage pipe set in gravel which connect up to the downspouts and sump pump outlet. The sump pump is much happier now and our electricity bill is lower! Since these trenches didn’t have to be very deep they could be dug by (my husbands) hand. 
  • The areas near the barn and greenhouse are both low lying so a lot of the problems there are due to the fact that water can’t run off and percolation is painfully slow due to the clay. More french drains and rock filled channels have improved things by the barn using gravity to divert the water away. 
  • The greenhouse is going to be raised up on cinder blocks, and a deep layer of gravel used in the interior to provide a dry platform. 
  • The major project is where I want to create a garden.  John Silvernale, landscape architect with Berg’s Landscaping designed a drainage system which involved bringing in the big boys; an excavator, hundreds of feet of pipe and 30 yards of gravel.
They dug a 4’ deep x 2’ wide channel from the top end of the border and linked it into the newly re-opened stream at the lower end, using a laser to get a suitable grade. Into that main pipe they have installed drainage ‘fingers’ every 10’ or so where secondary pipes connect at 90’. The channels were back-filled with gravel then the loosened soil. We are watching it over the winter to see if any adjustments need to be made but things are looking good. Water is draining out of the pipe into the stream but it is also seeping out of the gravel itself, which is acting like a dry well. Next spring we will bring in some good topsoil and start to plant our garden!

So how does this help you apart from making you smile? Assess the severity of any drainage problems you may  encounter. A little sogginess here and there definitely gives you the opportunity to grow water loving plants such as Astilbe and Japanese primroses. However if you feel like Noah looking out for dry land it may be time to get some help. Plus there aren’t many doves in Seattle…..

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