I request your help for two problems: Two types of plants appear to growing in an invasive fashion in my backyard. I do not know what they are or what to do about them. See picture "plants" Our gardenia produces many blossoms but most of them decay and wither before they mature. See Gardenia 1 and Gardenia 2 Thanks
Your first photo shows a type of perennial plant called spurge (Euphorbia characias). It is not considered invasive, but can spread and self-seed. You can pull out any you don't want and share them or plant them elsewhere.
We don't see a photo of a second spreading plant...maybe you forgot to attach?
Gardenias can be challenging to grow well enough to bloom.
They need the brightest light you can give them, but not direct sunlight.
They resent change. They like steady temperatures (62-63 degrees while the buds are forming, and a sudden change, or relocation can cause bud drop.
So can spider mites. Look for fine webbing with teeny, tiny dots that crawl when you shake them had and dislodge them over a piece of white paper.
They need high humidity, which is hard to accomplish in our forced-heat homes. Mist them (not their open flowers) regularly, or place the pot on a saucer of damp pebbles to give them more. Water them with slightly warm water. (lime free for these acid-loving plants.
If you have a place to put it outside for the summer, out of direct sunlight, it will be happy with our weather. (Wait a couple of more weeks)
I appreciate your help
In my particular case, the spurge is too invasive and I do not find it particularly ornamental, so I decided to pull it out.
I am attaching a couple of photos of the other plant that is rapidly spreading.
Regarding your advice regarding possible mites on the gardenia, do you mean to use just paper, no chemicals or soap?
The plants shown in you new photos are also spurge -- the same plant as in your initial photos. These are in the juvenile stage, without the flowers yet.
Regarding the gardenia, we were recommending that you shake the branch tips over a piece of white paper to see if any mites drop out. This is a test to see if mites are present. We don't see any in your photo. If you do see mites from this "shake test," you can treat with insecticidal soap. Do you have the gardenia outside or inside? The damage shown in you initial photos looks like it might be cold injury. Gardenias are very sensitive to cold and changes in their environment.
No, they will appreciate being outside in our humid summer, and our local insects tend to take care of pest insects they sometimes have.
They do not like full sun though, which can scorch the leaves. Give them the brightest position you can without full blazing sun all day.
Let it stay out until sometime in September/October, when night temperatures are in the mid-50s. That will allow them to set buds that will bloom in the winter.
Water well, making the whole pot moist, (you should see water drain from the bottom of the pot) and let the top half-inch of soil dry before watering again.
Fertilize with an "acid" fertilizer every 2 weeks March-September.