My main garden is a raised bed garden which follows the late Mel Bartholomew's Square Foot Gardening principles. It was developed in the US so it uses English measures based on 12 inches to a foot. The beds are divided into "squares" or square foot sections and plants are planted in squares based on their space requirements. Plants are planted in a grid with 1, 2, 4, 5, 8, 9, 12, or 16 per square. If a plant requires 3 inch spacing, for example a radish or carrot, it is planted in a grid of 16 plants per square. Beets and bush beans are planted nine per square, giving them 4 inch spacing.
The Square Foot Gardening method is superior from a number of perspectives. It makes highly efficient use of space in the garden, important to me because of my small garden. It makes garden planing and layout simple. The Mel's Mix soil blend is light and friable. It dries out quickly in the spring so you can plant earlier, and it is easy to weed. When planting seeds, all you need to do is mark out the planting pattern on the squares and plant. I usually use my finger and an approximation of the spacing. Then I ran across this device on Amazon.
This is the Seeding Square, a very clever device that makes it simple to layout the garden. This was funded by a kickstarter campaign and is manufactured in Canada from a very tough plastic. It is washable and waterproof, so it won't be ruined if you leave it out in the rain. One device accommodates all spacing and planting depths. It is flat, easy to store, and comes with a plastic zipper case. The planting patterns are color coded and it comes with a planting guide, a combination dibble/seeder, and a funnel. The dibble is marked in inches and has an embedded magnet to store it in the slot when not in use.
The shape of the device is like a pizza box. The raised sides are pressed into the soil, marking out the sides of the squares. The funnel stores underneath when not using.
The Seeding Square is started in the corner to align with the sides of the bed. The dibble is used to make planting holes at the necessary depth. If you want to use the seeding funnel, you can now plant your seeds.
Here I am planting this bed with bush beans, with a 9 per square spacing (the yellow holes). The squares and 2 inch holes were quickly laid out. Given the size of the bean seeds I did not use the funnel and chose to insert them with my fingers. The column to the left was planted with pole beans that will be trellised. For them, I use an 8 per square spacing, just the inner two rows of red circles.
When planting carrots, the funnel definitely was handy. Above I am seeding carrots in the space allocated to the now sadly deceased shallot plants. The small size of the carrot seed and the relatively shallow depth of planting hole makes the use of the funnel very handy. Two days of planting have proven the Seeding Square very handy and well worth the somewhat pricey $29 US.