Seed to flower/mushroom
Just some quick pointers here to get the more obvious details out of the way.  First, you should not use using namespace std;, but rather explicitly state which namespace you are using like this std::cout.  This prevents namespace clashes, and is discussed in great detail here.

Second, you should use braces around your if/else statements and loops even when there is only one statement after it:




if (soilMoist == wetCheck)
    cout &lt;&lt; "It's a sunflower!";
else
    cout &lt;&lt; "It's a dandelion!";



Should be:

if (soilMoist == wetCheck)
{
    std::cout &lt;&lt; "It's a sunflower!";
}
else
{
    std::cout &lt;&lt; "It's a dandelion!";
}


Right here, you should not indent your braces:


if (soilTemp &gt; 75)
    {
    if (soilMoist == wetCheck)
        cout &lt;&lt; "It's a sunflower!";
    else
        cout &lt;&lt; "It's a dandelion!";
    }



You do not do this in other areas, so I don't know why you did it here.

You should also not indent your cins:


cout &lt;&lt; "Enter the soil temperature: ";
    cin &gt;&gt; soilTemp;



You should have your prompts always specify exactly what the input should be.  Here, it looks as if you expect lowercase input: "Is the soil dry or wet? "  However, the program checks for uppercase input.  The best way to fix this would be to allow both "wet" or "Wet".

Otherwise, this looks pretty good.  However, one way you may want to consider expanding your program in is ensuring the user put in the right values instead of merely assuming the right values will be input.  You could do this with a do-while loop, among other ways.

This code is an example of what I mean:

string input = "";

do {
    if (input == "")
    {
        std::cout &lt;&lt; "Is the soil dry or wet? ";
    }
    else
    {
        std::cout &lt;&lt; "Invalid response.\nIs the soil dry or wet? ";
    }

    std::cin &gt;&gt; input;

} while (input != "Wet" &amp;&amp; input != "wet");