It's my understanding that Rhododendrons have compact root systems. I can put it in a 2' tall or larger pot if necessary. Will this work in a shaded area?
Also, if the pot idea is OK, I live in San Jose, CA and I'm fairly specific on the color I would like. I really love those translucent light pink or lavender blossoms. When I go to the Rhododendron society, they do have a list of proven performers for my area but only one meets my color requirements (davidsonianum ). If I search based on color no real cultural requirements are provided. In particular, my location gets very little direct sun - but there seems to be quite a bit of reflected light from the walls of my house as I have a Bouganvillea there now and it actually produces fairly profuse blooms when it gets hot.
Is there a mail order source or other reference which can provide me with detailed info. Or I suppose I could just call a reputable outfit and give them my requirements. I had no luck with the society nursery listings (online anyhow).
Hello, alexh. R. davidsonianum var. Sloane or var. R. Lyons should be nice addition for your home.
The reflected light that you mentioned sounds great because it is indirect and is needed for best flowering. However, make sure that the current location will also provide the rhody with adequate moisture levels and soil whose Ph Level is below 7.
Bouganvillea is a tropical tree that does not flower when the soil is always wet; the fact that your plant produces lots of blooms in there might indicate that the soil is somewhat dry, perhaps too much for a rhody. You know the place better than anyone else so tweak things to provide more moisture only if you need to.
There are many mail order companies that will provide cultural requirements but the catch is no one location will provide all the requirements that one wants to see. Calling or emailing are the best solution. I have not done business with these but check Lake Tapps Rhododendron Garden & Nursery in Washington State (http://www.rhodies.com), Species Unlimited also in Washington State (http://www.rhodospecies.com) and A Sandy Rhododendron in Oregon (http://www.rhodo.com). They are close to your neck of the woods.
Note: most nurseries will not be shipping at this time of the year but some will now accept orders for plants to be shipped later.
Thanks Luis, excellent advice. I ordered an R. Lyons.
I make my own potting soil mix which is optimized for excellent drainage which is of course especially important for Rhodies. I use fine Orchid bark + 10-15% peat moss by volume to make up for the porosity of the bark (although bark is much better at retaining moisture than any coarse mineral). Sometimes I also add some pearlite and 1/4" granite chips although I'm not sure it's of any real benefit. I have had the bark mix in some large planters for 3 years without any noticeable settling. I also use drip irrigation for most of my containers.
When I first came up with this mix, I tested the PH and it was slightly acidic as expected due to the peat. To compensate for this I usually add some dolomite lime which I verified does increase the PH.
For a Rhodie should I omit the dolomite all together (I could also test it but I try not to rely too heavily on home test kits) or would you recommend another planting medium?
PS. the bouganvillea is also in a container. I basically don't plant anything other than annuals in the groud where I live regardless of soil prep unless it's a raised bed or sometimes I get lucky and there's a plastic drain pipe under the plant and I poke a few holes in it and put gravel over it. Otherwise it's a losing battle.
I used to follow conventional wisdom - dig a large hole, fill it with potting soils and stick a plant in it and I have since realized that this is almost worse than just sticking it in the native soil. You are essentially creating a pot with no drain holes. Also, the salts from fertilizers have no where to go and will build up and burn the roots at the bottom of the hole. Even in my raised beds, where I have landscape sized plants I prepared the soil 3' down. This will still form a pot or trough, but hopefully the water will never acummulate to any large extent and there is plenty of breathing room for the roots in any case.
Definitely omit the dolomite - you want to target ph 6.0 or less. (5-6 I think). Peat's fine (so long as it's not all that's there - especially if it gets dried out); bark (especially composted bark) is good so long as you don't let the rhododendron dry out too much. Sand is also good.
Rhododendrons do have compact roots but not deep ones and so are very succeptable to drought. This means frequent watering when temps get above 80F. I use pots with good drainage holes and those that are only 10 " deep but are 2' in diameter to allow the roots to spread out. I also dig the pot into a hole in the soil keep the bottom and sides of the pot cooler. The soil mix should also be mostly pine bark finely shreaded mulch . The plants and pots do better in high shade. Some good mail order nurseries are Rare Find Nursery in Jackson NJ . email@example.com.. 732 833 0613
and Hammonds Acres of Rhodys. firstname.lastname@example.org 360-435-9206
and Whitney Gardens and Nursery Po box170, 306264 Hwy. 101 Brinnon WA 98320-0080 360 796 4411 email@example.com 800 952 2404
Their catalogs contain many color pictures and descriptions