If you open the pods up and the seeds inside are brown or otherwise mature looking they are ready to go, even if the pods are still green outside. Usually rhododendron seeds are sown in pots and grown on under cover.

Emboth, I got an answer on a different forum that said the same thing, so it is likely the way to go. They added for me to try to sow it on top of moss, and put in a bag to stay moist. They said to have a shallow flat of moss, I'm guessing with woodsy soil under it, and sow, and when I get seedlings, transplant to pots, and basically keep moist/shaded for 3-5 years before transplanting where they will stay. Also I should fertilize at 1/4 strength periodically. I am not sure if I can get the moss now. I am hoping I can get it up the mountains here where the rhodies grow naturally. If not, I have some reindeer moss from a crafts store, that I can put on top of the soil, but, it may not be the right thing, if the moss was sterilized, and chemicals are still present. I like to direct sow things where they will grow, but, I can see from the other response to the (basically the same) question on another forum, that they need to be coddled before growing outdoors in the ground. I did get a source to buy a little one also, but, still want to sow the seeds. Thanks for your answer also. If you have grown them before, are the babies easy to tell from weed seedlings? Thanks Emboth Poaky1

I have grown rhododendrons from seed the last couple of years but not Rh. maximum. However, the process for sowing most hardy rhododendron species is basically the same. Sowing in situ just does not work in my opinion. Too many factors that you cannot control (weather, insects, animals etc.).

How I do it? I use a sieved professional rhododendron potting compost to which I add some coarse sand for drainage. On top of this mixture I put some fine peat moss (usually this can be found in professional potting mixtures). Many people use spaghnum moss instead. I sow the rhododendron seeds on top of the peat moss. Do not cover the seeds as they need light to germinate. Lightly mist the top of your sowing. Then put a clear plastic cover on top of the pot and place the pot somewhere light but out of direct sunlight. Temperature should be about 20 degrees Celsius/ 68 degrees Fahrenheit.

Most rhododendron seeds germinate in 2 to 3 weeks time. I've heard that there are some clones of Rhododendron maximum that take longer to germinate but I do not know if this is true. I usually sow rhododendron seeds in early spring. If you have access to growing lights it can also be done in autumn or winter. For the first few months the rhododendron seedlings are very tiny and vulnerable. I leave the clear plastic cover on for at least 6 to 8 weeks and then remove it. Keep sure to keep the pot out of direct sunlight. I do not water the seedlings from above as this can lead to fungus problems. I pot the pot in a saucer with water and when the sowing mixture is saturated I take it out. Some people prick the seedlings out after 2 to 3 months but I leave them in the pot for at least another year. After 1 year I seperate the seedlings and grow them on in individual pots (small ones to reduce the risk of the seedlings getting too wet and getting root rot).

I don't have any problems with weeds in my rhododendron sowings as I use a weed free potting mixture. If you leave your rhododendron seedlings in a pot for some time you can get trouble with liverwort but as long as this does not smother the seedlings everything should be OK.

Gardenprince, Thanks for the info. I have gone today and gathered some moss and a little soil from where the native rhodies are near me. I also got some sphagnum moss from Lowes, the long pieces. I want to put the soil from the woods mixed with some of my leaf mold bunny poo compost, and some used potting soil, and put a thin layer under the moss, and moisten (not drench) and put in a flat and sow the seed once the seed trusses get brown and open, keep in a bag until the babies come up. I have flourescent lights in the basement, plus a window. The basement pretty much stays at 68 F, or close to it. I have a big cart to put the flats on so they won't be in too much sun, I can put the cart a couple feet from the window. I don't like to use the fine peat moss, it seems to not want to absorb water for me. I have gotten some tips from another GW er on the same subject, and they preffered using live moss from the woods, most else is the same as far as the moss and cover to keep moist etc. And the not direct sowing. I appreciate the help from you both. If I remember, when/if I successfully get seedlings, I will post pics. Thanks GP poaky1

It's true that peat moss dries out rather quickly once you remove the plastic cover. It is important that you check on a regular basis to see if the top layer of the pot is adequately moist.

Here is a pic from two rhododendron species that I sowed. On the right you see 1 year old seedlings from Rhododendron makinoi, on the left are seedlings from Rhododendron fortunei that I sowed in early April 2015. Seed from both species was from the American Rhododendron Society's seedlist.

All look great GP. I hope those that sprout for me of the Rhod. Maximum, do that good. poaky1