In a pot you say, a clay pot. Same soil they where planted in long ago when they were young. Hm.
I suspect that this may have something to do with it.
I think we have all heard that hydrangeas need to have pennies in the hole to produce blue flowers - a Half truth, they do need more copper in their diet Copper in the soil for them promotes blue flowers.Pennies today are made mostly of zinc, not much copper there anymore
All plants get their color and food and health from the soil. Energy is taken from the sun where plants convert sunlight to sugars, but plants are more than just sugar.
It is possible that the soil in the pot, or the pot themselves is having an impact on the geraniums and their color.
You can either try to fix this with a fertilizer, which may not work because fertilizers provide three chemicals and if you don't know what is lacking in the soil you may not fix it. A quick summery of store bought chemical fertilizers:
All fertilizer labels have three bold numbers. The first number is the amount of nitrogen (N), the second number is the amount of phosphate (P2O5) and the third number is the amount of potash (K2O). These three numbers represent the primary nutrients (nitrogen(N) - phosphorus(P) - potassium(K)).
This label, known as the fertilizer grade, is a national standard.
Nitrogen promotes green foliage and stem growth, phosphorus encourages flowering and root production, and potassium contributes to overall strength and disease resistance. Fertilizers for flowering plants usually contain a higher percentage of phosphorus and potassium and less nitrogen.
A bag of 10-10-10 fertilizer contains 10 percent nitrogen, 10 percent phosphate and 10 percent potash.
Most fertilizers contain a plethora of trace elements and chemicals, some do have copper, others do not. Thus you have a wide variety of additional chemicals you can throw into the mixture, EXAMPLE copper Sulfate is used sometimes in some conditions to promote color change in plants (Back to the hydrangeas).
Another, far easier method which may work for you is too change the soil with a good potting soil mixed with composted material. Say 1 part compost to 2 parts potting soil, line the clay pot with a heavy duty plastic, making certain that drainage is still possible through the bottom.
Why the Lining? Two reasons. Clay (terra Cotta) is porous and will leach salts and wick water from the plant.
Then depending on who made it, the clay pot may have higher amounts of certain things. EXAMPLE Mexican Terra cotta has a higher amount of Lead than the US version. Other trace elements come in different levels. Since you don't know what those are and its is highly likely that these are effecting the color, barricade from absorption of these by the plant is called for.
Now if you have read me before around here you always hear me talking about Compost Tea and singing the praises of compost. I stand by the notion of compost simply because I have found that the more compost I add each year to my gardens the better my garden grows. And lawn, and bushes and trees, etc.
Compost is composed of organic material, leaves, twigs, egg shells, coffee grounds, uneaten vegetables, grass clippings, etc. etc. etc. All of these are rich in nutrients and trace minerals. The process of rotting breaks down complex molecules into simpler ones and even converts some of them into oxides, sulphate's and carbons and other mixes. These make a natural fertilizer which nature has been making since plants emerged on the land. Indeed, go into any forest and move away the new fallen leaves and you will find a thick layer of composted material. they provide a full diet, especially if they are composed of a mix of vegetables. For instance Corn Cobs are high in nitrogen, egg shells provide calcium, etc.
The specific mixture of chemicals is variable, however it provides all the chemicals a plant needs in high amounts than any fertilizer on the shelf. It may have lower N P K, but it has over all higher levels of everything else and as such will provide a long lasting supply of food (if mixed with soil at 1:2 ratio, than adding miracle grow or other fertilizers.
You can buy compost at the store, or you can make your own. Depends on your needs. I have two acres of land, lots of grass and trees. I could either pay to ship off all of that trimmings, or I can throw it in a pile and let nature break it down and then use a shovel and spread the black stuff around. Guess which one I picked
Compost heaps do not have to be that big, nor do you need to understand chemistry to make one, nor do you even have to have a special box, or turn it all the time. Its easy money in the garden.
Store bought compost is made from all of the green waste thrown out by everyone who use those green trash cans. Unfortunately you don't know if they used pesticides, fertilizers, herbicides, thus you are getting and iffy product. I would never, ever use a store bought compost for vegetables because I do not know what is really in the mix.
I know too much data again.
David
