This week I choosen a plant which is a problem in some places but not here. I first noticed it growing along the road which leads to the Victoria Airport. I took this route going into Sidney when I lived closer into town. I, of course, had to stop for a closer look. The yellow color was out of character for what I suspected it was. It looked like a form of plant which grows wild here but is blue or rarely pink or white. it also seemed much larger than what i would have expected. What I had discovered was some wild Tree Lupine (Lupinus arboreus) orYellow Shrub Lupines which are growing in the far north reaches of their native territory. They were a glorious golden yellow amoungst the grass waste area.
Lupines and all members of the Pea((legumes) family(Fabaceae) are know to be able to improve the soil in the area in which they grow. they do this by taking nitrogen in the air and converting into an important usable nutrient which all plant need to grow. Members of the Pea family are able to do this by having special(symbiotic) bacteria called Rhizobia which are located in nodules located their roots. When these plants die they release the nitrogen back into the soil for other plants use. this is why members of they Pea family members such as alfalfa and peanuts are grown as a crop then plowed under before they ripen to enrich the soil. The problem has been when these plants escape from cultivation because they go to seed, this is easily solved in your own garden by removing the spent flowers.
Fortunately for us Lupinus arboreus is an attractive and generally short lived perennial or shrub. It is nothing like the Broom or gorse which was brought here and have overtaken areas. Tree Lupines have a very well defined natural area of growth in Western North America. It needs to be fairly close the the ocean and humidity to survive and trhive. In it’s natrual setting it is usually found within 5 km(3 miles) of the coast here. It grows from Southern California up the coast to the Southern part of British Columbia and on the southern tip of Vancouver Island
Tree Lupines definately are not long lived here and no longer are found where I originally spotted it. This year I found it along a road on the other side of the airport. I had spotted it there a couple of years ago, but not in between. This year it reappeared in several spots where the soil has been disrupted along an area which will be built on soon. The exciting thing was there were 2 color forms, the pale creamy and the bright golden types.
It can indeed grow to be a quite large plant in a sheltered area. There is a very large bright yellow Lupinus arboreus growing along Lockside Drive which i stopped to check out. I wanted to see if it was more than one plant as it was much larger than others I have seen. I looked behind it and saw a single inch(2cm) thick stem supporting the 5ft(1.5m) by 4ft(1.25m) brightly blooming shrub. it looks like it has been there several years.
If you want to grow a Tree Lupine it is easy. they like well drained soil which does not need to be rich (they do that for you). Full sun is a must to produce the best crop of flowers. Shelter from winters coldest winds will help it overwinter as it is fairly tender being rated zone 8 (-10 to 12c). remove the all the spent flowers except for one or two stalks if you want it to reseed. Seed naturally will germinate during the damp winter and will flower between May and August depending on where you are. You will be rewarded with a beautiful delicate looking Lupine which is pleasantly fragrant and long blooming.
More About Tree Lupines:
Wiki article about Tree Lupines: http://en.wikipedia.org/wiki/Lupinus_arboreus
the best source of information on germination of all types of plants i have seen anywhere. These methods work!
Nitrogen fixing plants and how it works: http://en.wikipedia.org/wiki/Nitrogen_fixation