When you'd like to get a head start on your planting for the season, it's sometimes best to begin your plants indoors! By using an egg carton to start seeds, you can reuse a common household product and avoid buying small pots, thus reducing consumption.
If you're looking to get a head start on planting spring crops [which tend to be root crops (including carrots, beets, and radishes), leafy greens, broccoli, and cauliflower], you should begin your seeds indoors in the winter cold. This way, when the weather begins to warm and you are ready to transplant them to your garden, your plants will have already started to grow. If you plan to get a head start on your summer vegetables [which include tomatoes, peppers, eggplant, watermelon, most vegetables that you actually eat the fruit of the plant], you should begin your indoor seeding once your spring plants are in the ground.
I do not recommend a specific time frame to start your seeds, because these estimates vary greatly with geographic location. For example, if you live in Boston, Massachusetts, where it stays colder longer, you might want to start your tomatoes a bit later than if you live in Richmond, Virginia. Luckily, there are countless resources online to help you make an informed decision as to when you should begin your indoor planting. I would consult those resources before continuing with this instructable.
Step 1: Preparing the Egg Carton
To begin, take an empty egg carton and cut it in half as shown. Using plastic wrap, cover the top part of the egg carton. To keep the plastic wrap in place, you may use four small pieces of tape, staples, etc. The plastic wrap is helpful to maintain the warmth and moisture of the seeds and seedlings.
Be sure to poke holes in the bottom of each dimple. The holes will allow excess water to escape, thus protecting the seeds and seedlings from over-watering.
Step 2: Getting Ready to Seed
Add dirt to each dimple of the egg carton, filling each dimple to the rim. Then, using your finger, make small indentations in the dirt.
Note: the optimal depth of the planted seed beneath the ground varies with different plants. For spinach, arugula, and other leafy greens, seeds should be planted at a depth of 1/2". Many roots vegetables should also be planted 1/2" beneath the ground; carrots, however, require a depth of only 1/4". Similarly, tomato and pepper seeds can be buried 1/4" beneath the surface. If you are unsure of the depth you should plant your seeds, you can find the answer via an online search engine.
Step 3: Plant!
Next, you should add your seeds to the indentations. In each individual dimple, you should add between two and four seeds. Since not all seeds will germinate, you should hedge your bets by putting multiple seeds in each pod. If multiple seeds end up germinating (and becoming little seedlings!), that is not a problem. You can always separate the seedlings from each other at a later time, when you transplant the seedlings into the ground. The process of separating seedlings is called 'thinning' and is essential to gardening. If you have too many plants too near each other, they will compete for resources, including sunlight, water, and nutrients, and essentially starve each other.
Once you've added the seeds, be sure to cover with dirt.
Step 4: Maintaining Plants Indoors
Once you've planted the seeds, you should water them immediately. You should water so that the soil is moist, but not overly saturated.
Be mindful of the dampness of the dirt while your seedlings are indoors. Egg cartons make convenient planting partners, but their small size can put your seeds at risk of drying out. In order to avoid this, be sure to add the cover, which should have plastic wrap over it, overnight.
Depending on the plant and soil conditions, it takes 1-2 weeks to germinate. In this time, be sure to water and keep warm. When the seedlings do sprout, be sure to keep them in a safe environment with lots of sunlight, like a windowsill.
Step 5: Transplanting
When the seedlings grow large enough and when the weather warms outside, you should transplant your plants into the ground. If the seedlings seem to be getting too big for the egg dimples, but the weather has not warmed sufficiently for outdoor planting, feel free to transplant your seedlings to larger containers.
When transplanting, make sure to loosen the dirt in each egg dimple. Ideally, damage to roots will be minimized during the transplanting process. Reach your fingers down to the bottom of the egg dimple and grab most of the dirt, including the seedling and its roots. Then, you can place the seedling in a small hole in your outdoor garden. Finally, cover the base of the seedling with additional dirt from your garden.
Alternative transplanting method: If you are concerned about damaging the roots of the seedlings while transplanting or want to save some time, you can also cut the pods into individual sections and plant them directly into the ground. You can do this because the egg cartons are biodegradable! If you'd like to do your transplanting this way, however, I would suggest making some sizable slits along the sides of the individual pods (starting from the bottom hole of the pod) so that the roots can grow freely easily.
Be aware of how far you space your plants away from each other. If you plant your seedlings too close, they will compete for resources and will not grow to their full potential. If you plant them too far away, you will not maximize the space in your garden. For more information about how far away you should plant different crops from one another, consult your favorite online search engine. As mentioned, there is a plethora of information online that will help you grow a successful garden.