Consider the following:
Where is the best space at your home for a garden?
Is it indoors or outdoors?
What is your budget?
Do you need to purchase items or do you already everything you need?
What do you want to grow and how much?
Flowers... vegetables... herbs... trees. What you want to grow will determine how much space or the containers you will need. Keep in mind different plants require different temperatures, amounts of light, water, and time to grow before you can harvest from them. Make sure you plan what you are going to grow and when you are going to plant it to make sure your garden is a success!
What kind of containers will you use?
If you are planting indoors, check out this link for some fun DIY ideas. If you are planting outdoors, this link has some fun low-cost ideas for containers.
What are the conditions like where you plan on starting your garden?
Is there enough light? If it is indoors, does it get really cold or hot there during the day? Are there any animals or pests that can cause damage to your garden in the area?
