C# เกี่ยวกับการ insert วันเวลาครับ ช่วยด้วยครับ !!!

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ProjectVB
{
    public partial class FRM_Vb : Form
    {
        plant myPlant = new plant();

        public FRM_Vb()
        {
            InitializeComponent();
        }
        SqlConnection th = new SqlConnection("Server=DESKTOP-35EE4RH\\SQLEXPRESS; Database=Projectcs; Trusted_Connection=True;");
        private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {

        }

        private void ปดโปรแกรมToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void ยอนกลบToolStripMenuItem_Click(object sender, EventArgs e)
        {
            MENU main = new MENU();
            main.Show();
            this.Hide();
        }

        private void FRM_Vb_Load(object sender, EventArgs e)
        {
           

            try
            {
                th.Open();
                Showdata();



            }
            catch
            {
                MessageBox.Show("Error");
            }
        }

        private void Showdata()
        {
            string sql = "Select * From tblVb WHERE Vb_Name LIKE'%'+'" + textBox4.Text.Trim() + "'+'%'";

            SqlCommand com = new SqlCommand(sql, th);
            SqlDataReader dr = com.ExecuteReader();
            DataTable tb = new DataTable();
            if (dr.HasRows)
            {
                tb.Load(dr);
                dataGridViewADD.DataSource = tb;

            }
            else
            {
                dataGridViewADD.DataSource = null;

            }
            dr.Close();
        }

        private void Cleardata()
        {

        }
        private void button1_Click(object sender, EventArgs e)
        {
            this.Close();

        }

        private void button3_Click(object sender, EventArgs e)
        {
            myPlant.name = txtName.Text;
            myPlant.price = Int32.Parse(txtPrice.Text);
            myPlant.harvestDay = Int32.Parse(txtHarvest.Text);
            myPlant.plantingDate = dateTimePicker1.Value;
            myPlant.nurseryDay = Int32.Parse(txtNoA.Text);

            if (myPlant.verifyNurseryDay())
            {

                string sql = "INSERT INTO tblVb (Vb_Name,Vb_Price,Vb_HarvestDay,Vb_Plant,Vb_NurseryDay) VALUES ('" + myPlant.name + "','" + myPlant.price.ToString() + "','" + myPlant.harvestDay.ToString() + "','" + Convert.ToDateTime(myPlant.plantingDate) + "','" + myPlant.nurseryDay.ToString() + "')";
                SqlCommand com = new SqlCommand(sql, th);
                com.ExecuteNonQuery();
                MessageBox.Show("บันทึกเรียบร้อยแล้ว");
                MessageBox.Show(myPlant.aboutPlant());
                Showdata();
                Cleardata();
            }
            else
            {
                MessageBox.Show("มีปัญหาแล้ววันที่อนุบาลมากกว่าวันที่เก็บเกี่ยว กรุณาตรวจสอบข้อมูลให้ถูกต้อง");
            }

            
            
            
        }
    }
}