What's blooming in Vancouver - April 25 pt 3

Dicentra formosa or Pacific Bleeding Heart

A couple of excellent ground covers for the deep shade garden are Dicentra formosa and Oxalis sp.  I want to emphasize that the Oxalis is good in deep shade, because I believe the lack of light may slow its progress.  There can be a danger of the Oxalis being invasive.

There are about 500 varieties of Oxalis spp, and I can't remember which one is shown in the top photo.  I can say that it grows beautifully all year round, and tumbles gracefully over the paver driveway, softening the hard edge.  In this situation, the Oxalis is growing at the feet of Rhododendrons and Oemleria.

Dicentra, or Bleeding Hearts, are such unusual flowers.  The native D. formosa has feathery leaves and smaller flowers than the classic Dicentra.  Like the Oxalis, Dicentra spreads by rhizomes.  If the soil is loose, these will spread easily.

Leaving the leaves in spring

Every autumn, we cover the garden beds with leaves to protect the soil.  Keeping the leaves on site has many advantages.  

1.  Plants take up nutrients, and when the plants die back for the year, if left on site, the nutrients will go back into the soil.

2.  The average rainfall in Vancouver between October 1st and April 30th is 1150 mm or 3.75 feet for the seven months.  The average raindrop hits the ground at 24 kph or 15 mph.  This amount of water hitting the soil creates a tremendous amount of compaction.  An inch of mulch on top of the soil absorbs the impact of this much water on the soil.

3.  If the soil is protected from rain, and does not get compacted, all the useful little critters and microbes stay alive to do their good work for another season.

Often, we are asked when we will be removing the leaves in the spring.  The answer is usually, we won't remove the leaves.  An ecologically designed garden has many tiers of plants covering the soil.  In the spring, as the deciduous plants rise from the soil, they cover the decomposing leaves.  By summer, the leaves have decomposed back into the soil to provide nutrients for the earth again.

The only time we remove leaves is if they are so filled with tannins (i.e. oak, beech), that they will blow all over before they ever decompose.  These leaves go into the compost where their decomposition is accelerated.  These leaves can stay at the back of beds behind or beneath plants, but we do remove them from front entrance or feature beds.

Whenever we can, the autumn leaves get mowed up before being applied to garden beds.  Mowing the leaves speeds up decomposition, and makes the leaves small enough to provide a mulch and allows moisture to penetrate to the soil.

What looks good now in Vancouver? pt 1

Gardens are not only for flowers, but we need to think of complementary shades of green, contrasting textures of foliage, and different shapes of leaves.  Not many plants flower in winter, but many plants are evergreen or have some other interesting quality to feature in a winter garden.

Arum italicum makes a lovely ground cover for winter.  The shiny, elongated heart shaped leaves are highlighted with white veining.  Other Arum species do not have the decorative leaves.  

Come summer, the leaves die down and give way to long stalks holding spires of orange berries.