 
      Here's the English translation of the provided Japanese blog article:
When working with Django models,
from django.db import models
class Article(models.Model):
    text = models.TextField()
and you view the Django Admin management site, you will see HTML output like <textarea .... rows="10" ... .
If you want to change the value of the rows attribute, you can do so in admin.py like this:
# -*- coding: utf-8 -*-
from django.contrib import admin
from blog.models import Article, Category
from django.db import models
from django import forms
class AdminTextareaWidgetLarge(forms.Textarea):
    def __init__(self, attrs=None):
        final_attrs = {'class': 'vLargeTextField', 'rows': 40}
        if attrs is not None:
            final_attrs.update(attrs)
        super(AdminTextareaWidgetLarge, self).__init__(attrs=final_attrs)
class ArticleAdmin(admin.ModelAdmin):
    formfield_overrides = {
        models.TextField: {'widget': AdminTextareaWidgetLarge},
    }
admin.site.register(Article, ArticleAdmin)
You can create a new widget like this and put it into formfield_overrides.
If possible, I would like to achieve this by defining only 'rows': 40 somewhere, but I couldn’t figure out how to do it.
There's also the option of directly rewriting django.forms.widgets.Textarea, but that’s not a good idea.