Wordpress Custom PHP failing at wpdb object - php

Question

I am trying to create a form on wordpress that automatically updates a custom table in the database. The form works with the "POST" method and calls the PHP file fine, and any code (such as echos) I enter at the beginning work fine. The problem is every time I try and use the wpdb object, the screen is just white and the code stops. It won't run anything including or past where I call wpdb. I have tried both using insert and get results and neither is working. Also, I am getting absolutely no errors in the console output even though I turned debugging on and everything.
This is my php file (which has a permission value of 755):
<?php
global $wpdb;
error_reporting(E_ALL);
echo "New Plant has been submitted.\n";
$plantname = $_POST["name"];
echo "Before";
$myrows = $wpdb->get_results( "SELECT * FROM wp_users" );
exit( var_dump( $wpdb->last_query ) );
echo " After: " . $myrows;
$wpdb->insert('Plants',array('PlantName' => $plantname),array('%s'));
echo $plantname . " has been submitted.";
?>
</body>
</html>
Also, this is my form:
<form action="cgi-bin/add_plant.php" method="post">
Plant Name: <input name="name" type="text" />
Lowest Ideal Temperature: <input name="IdealTempLow" type="text" />
Highest Ideal Temperature: <input name="IdealTempHigh" type="text" />
Lowest Ideal pH: <input name="IdealpHLow" type="text" />
Highest Ideal pH: <input name="IdealpHHigh" type="text" />
Lowest Ideal Humidity Level: <input name="IdealHumLow" type="text" />
Highest Ideal Humidity Level: <input name="IdealHumHigh" type="text" />
Lowest Ideal Moisture Level: <input name="IdealMoistLow" type="text" />
Highest Ideal Moisture Level: <input name="IdealMoistHigh" type="text" />
<input type="submit" />
</form>
By the way, I know I need to sanitize my code, but for right now I just want to be able to get it to work in the first place. I know that nothing is getting added because I logged in to PHPMyAdmin and there is nothing in the table. I also tried getting results from the standard wp tables, but that failed as well.
Edit 1
I have moved everything into a custom template file. I had gotten it working with the separate php file, but I moved it so that I could do form validation and everything all without switching pages. However, now I am having the same error. I had used "require_once" to include wp-load.php in the original and it worked, however now wpdb is still failing and I can't figure out how to include wp-load without it also failing. Originally loading up the page works: I can submit the form however on submit the page fails.
<?php
require_once(ABSPATH . '/wp-config.php');
require_once(ABSPATH . '/wp-load.php');
?>
<?php global $asteria;?>
<?php
get_header();
?>
<?php global $wpdb;?>
<?php
function test_input($data)
{
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}
function selfURL()
{
$ret = substr(strtolower($_SERVER['SERVER_PROTOCOL']),0,strpos( strtolower($_SERVER['SERVER_PROTOCOL' ]), "/") );
$ret .= ( empty($_SERVER['HTTPS']) ? NULL : ( ($_SERVER['HTTPS'] == "on") ? "s" : NULL) );
$ret .= "://" . $_SERVER['SERVER_NAME'];
$ret .= ( $_SERVER['SERVER_PORT'] == 80 ? "" : ":".$_SERVER['SERVER_PORT'] );
$ret .= $_SERVER['REQUEST_URI'];
return $ret;
}
function submitPlant($a, $b, $c, $d, $e, $f, $g, $h, $i)
{
$wpdb->show_errors();
// $wpdb->replace('Plants',
// array(
// 'PlantName' => $a,
// 'IdealTempLow' => $b,
// 'IdealTempHigh' => $c,
// 'IdealPHLow' => $d,
// 'IdealPHHigh' => $e,
// 'IdealHumidityLow' => $f,
// 'IdealHumidityHigh' => $g,
// 'IdealMoistureLow' => $h,
// 'IdealMoistureHigh' => $i
// ),
// array(
// '%s',
// '%f',
// '%f',
// '%f',
// '%f',
// '%f',
// '%f',
// '%f',
// '%f'
// )
// );
// $a = $wpdb->insert_id;
// if ($a == false) {
// $SubmitMsg = "Plant entry failed. Please contact system admin.";
// echo "Error: " . $wpdb->print_error();
// } else {
$SubmitMsg = "New Plant has been submitted.";
// }
return $SubmitMsg;
}
... Validation Functions...
?>
<?php
$PlantName = $IdealTempLow = $IdealTempHigh = $IdealpHLow = $IdealpHHigh = $IdealHumLow = $IdealHumHigh = $IdealMoistLow = $IdealMoistHigh = "";
$NameErr = $LTempErr = $HTempErr = $LpHErr = $HpHErr = $LHumErr = $HHumErr = $LMoistErr = $HMoistErr = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$SubmitMsg = "";
...Form Validation...
if (($NameErr == "") && ($LTempErr == "") && ($HTempErr == "") && ($LpHErr == "") && ($HpHErr == "") && ($LHumErr == "") && ($HHumErr == "") && ($LMoistErr == "") && ($HMoistErr == ""))
{
$SubmitMsg = submitPlant($PlantName, $IdealTempLow, $IdealTempHigh, $IdealpHLow, $IdealpHHigh, $IdealHumLow, $IdealHumHigh, $IdealMoistLow, $IdealMoistHigh);
}
}
?>
<!--Content-->
<div class="fixed_site">
<div class="fixed_wrap singlefx">
<?php if(($asteria['page_type_id']) == '1'){ ?>
<div class="page_tt">
<div class="center"><h1 class="postitle"><?php the_title(); ?></h1></div>
</div>
<?php } ?>
<div id="content">
<div class="center">
<div class="single_wrap no_sidebar">
<div class="single_post">
<?php if(have_posts()): ?>
<?php while(have_posts()): ?><?php the_post(); ?>
<div <?php post_class(); ?> id="post-<?php the_ID(); ?>">
<?php if ( is_user_logged_in() || is_admin() ) { ?><div class="edit_wrap"><i title="<?php _e('Edit This','asteria'); ?>" class="fa-edit"></i></div><?php } ?>
<div class="single_post_content">
<?php if(($asteria['page_type_id']) == '2'){ ?><h1 class="postitle"><?php the_title(); ?></h1><?php } ?>
<div class="thn_post_wrap"><?php the_content(); ?> </div>
<div style="clear:both"></div>
<div class="thn_post_wrap"><?php wp_link_pages('<p class="pages"><strong>'.__('Pages:').'</strong> ', '</p>', 'number'); ?></div>
</div>
</div>
<?php endwhile ?>
</div>
<?php endif ?>
<span style="color:blue"><?php echo $SubmitMsg;?></span>
<form action="<?php echo selfURL(); ?>" method="POST">
Plant Name: <input name="PlantName" type="text" value="<?php echo $PlantName;?>"/><span style="color:red"> * <?php echo $NameErr;?></span>
</br><div height="5"> </div>
Lowest Ideal Temperature: <input name="IdealTempLow" type="text" value="<?php echo $IdealTempLow;?>"/><span style="color:red"> * <?php echo $LTempErr;?></span>
</br><div height="5"> </div>
Highest Ideal Temperature: <input name="IdealTempHigh" type="text" value="<?php echo $IdealTempHigh;?>"/><span style="color:red"> * <?php echo $HTempErr;?></span>
</br><div height="5"> </div>
Lowest Ideal pH: <input name="IdealpHLow" type="text" value="<?php echo $IdealpHLow;?>"/><span style="color:red"> * <?php echo $LpHErr;?></span>
</br><div height="5"> </div>
Highest Ideal pH: <input name="IdealpHHigh" type="text" value="<?php echo $IdealpHHigh;?>"/><span style="color:red"> * <?php echo $HpHErr;?></span>
</br><div height="5"> </div>
Lowest Ideal Humidity Level: <input name="IdealHumLow" type="text" value="<?php echo $IdealHumLow;?>"/><span style="color:red"> * <?php echo $LHumErr;?></span>
</br><div height="5"> </div>
Highest Ideal Humidity Level: <input name="IdealHumHigh" type="text" value="<?php echo $IdealHumHigh;?>"/><span style="color:red"> * <?php echo $HHumErr;?></span>
</br><div height="5"> </div>
Lowest Ideal Moisture Level: <input name="IdealMoistLow" type="text" value="<?php echo $IdealMoistLow;?>"/><span style="color:red"> * <?php echo $LMoistErr;?></span>
</br><div height="5"> </div>
Highest Ideal Moisture Level: <input name="IdealMoistHigh" type="text" value="<?php echo $IdealMoistHigh;?>"/><span style="color:red"> * <?php echo $HMoistErr;?></span>
</br><div height="5"> </div>
<input type="submit" name="submitted"/>
</form>
</div>
<!--PAGE END-->
</div>
</div>
</div>
</div>
<?php get_footer(); ?>