RezzidenT, во. Нашёл причину.есть цену сделать 100. Тогда он выводит ошибку. Значит сама ошибка не в цмклах и в расчете цене. Значит в этом
$q=mysql_fetch_array(mysql_query("SELECT * FROM `ground` WHERE `id_user` = '$user[id]' AND `id_plant` != '0' AND (`time_water` = '$time' OR `time_water` < '$time') AND `time` > '$time' AND (`soil` = '0' AND `time_soil` > '$time' OR `soil` = '1')"));
$voda=mysql_fetch_array(mysql_query("SELECT * FROM `plant` WHERE `id` = '$q[id_plant]'"));
$vodaqwe=$voda['voda']*$q;
RezzidenT, да я уже и так сделал
$postaqwea=mysql_result(mysql_query("SELECT COUNT(*) FROM `ground` WHERE `id_user` = '$user[id]' AND `id_plant` != '0' AND (`time_water` = '$time' OR `time_water` < '$time') AND `time` > '$time' AND (`soil` = '0' AND `time_soil` > '$time' OR `soil` = '1')"),0);
$postaa=mysql_query("SELECT * FROM `ground` WHERE `id_user` = '$user[id]'");
while($posast=mysql_fetch_array($postaa))
{
$voda=mysql_fetch_array(mysql_query("SELECT * FROM `plant` WHERE `id_plant` = '$posast[id_plant]'"));
}
$vodaqwe=$voda['voda']*$postaqwea;