Overview
In this tutorial, we show you how to set border color of TextField in JavaFX.
Set Border Color Of TextField using JavaFX Scene Builder 2.0
If you are using 
JavaFX Scene Builder 2.0, go to the Style of the TextField in the Properties section of the Inspector panel. 
Add Css Style: 
-fx-text-box-border:  #B22222;
-fx-focus-color: #B22222
Set Border Color Of TextField by edit *.fxml file
Edit Example.fxml file, then Add CSS Style 
style="-fx-text-box-border: #B22222; -fx-focus-color: #B22222;" to TextField tag.
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.image.*?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" fx:id="main" prefHeight="400.0" prefWidth="600.0" style="-fx-background-color: #FFE4C4;" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.jackrutorial.ExampleController">
   <children>
      <TextField layoutX="150.0" layoutY="169.0" prefHeight="50.0" prefWidth="300.0" promptText="This is JackRutorial.Com" style="-fx-text-box-border: #B22222; -fx-focus-color: #B22222;" />
      <Button layoutX="150.0" layoutY="253.0" mnemonicParsing="false" prefHeight="50.0" prefWidth="300.0" text="Go" />
   </children>
</AnchorPane>
Set Border Color Of TextField using javafx.scene.control.TextField.setStyle
Using method 
javafx.scene.control.TextField.setStyle 
    @FXML
    private TextField txtDescription;
    /**
     * Initializes the controller class.
     */
    @Override
    public void initialize(URL url, ResourceBundle rb) {
        txtDescription.setStyle("-fx-text-box-border: #B22222; -fx-focus-color: #B22222;");
    }
Full Source Code
ExampleController.java
package com.jackrutorial;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.TextField;
public class ExampleController implements Initializable {
    @FXML
    private TextField txtDescription;
    /**
     * Initializes the controller class.
     */
    @Override
    public void initialize(URL url, ResourceBundle rb) {
        txtDescription.setStyle("-fx-text-box-border: #B22222; -fx-focus-color: #B22222;");
    }
}
Example.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.image.*?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" fx:id="main" prefHeight="400.0" prefWidth="600.0" style="-fx-background-color: #FFE4C4;" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.jackrutorial.ExampleController">
   <children>
      <TextField fx:id="txtDescription" layoutX="150.0" layoutY="169.0" prefHeight="50.0" prefWidth="300.0" promptText="This is JackRutorial.Com" />
      <Button layoutX="150.0" layoutY="253.0" mnemonicParsing="false" prefHeight="50.0" prefWidth="300.0" text="Go" />
   </children>
</AnchorPane>