All through the long winter months, I have been collecting empty cottage cheese, yogurt, and other medium-sized plastic containers to use for my vegetable seedlings. Vegetable seedlings (or any type of seedling), is the young tender plants that have just sprouted from their seed casings to begin their plant journey. Just like any newly born creature, plants need special care when they are young in order to develop into strong healthy plants that produce premium vegetables.
Two weeks ago, I started my vegetable seeds in plastic seed starter containers, 142 seed starter cells to be exact (I have previously written about conditions needed for seed germinate), and now have seedlings growing in each cell.
When planting the tiny seeds of broccoli, pepper, and tomato, more than one seed fell into a single cell (this is sometimes hard to avoid), which in turn produced multiple seedlings per cell. These extra seedlings needed to be thinned out in order to create space for the more superior or stronger plants to grow. To remove the smaller and weaker looking seedlings, I either snipped them off near the top of the soil with a pair of small pointed scissors, or gently lifted them out of the soil with tweezers.
Seedlings that grow in the starter cells or flats, as they are often called, are highly susceptible to what is known as, “dampening-off.” Dampening-off pertains to several soil borne fungal diseases. The symptoms of dampening-off relating to seedlings include the seedlings withering right after breaking through the soil, healthy looking seedlings falling over, or discoloration, wilt, and finally death.
To prevent dampening-off, make sure you do not over water the seedlings (misting lightly may be the best way to water), there is adequate drainage, do not allow overcrowding (as described above), and ensure air is circulating around the seedlings.
Once your seedlings have gained significant height and strength (you will know this by the fact that they are outgrowing their individual cell area), and before transplanting them outside, you will want to move them to a larger growing container. This is where the cottage cheese, yogurt and plastic containers prove useful.
Punch several holes in the bottom of each container for drainage, and fill with damp organic seed starter soil. Gently loosen the soil from around the seedlings (an old dinner fork makes this task easy), and carefully lift the seedling out of the starter cell. Place the seedling in the larger plastic container. Depending on the type of plant, I might put two seedlings in one container. Continue to care for the seedlings until they are ready for planting outdoors.
NOTE: To help prevent dampening-off, try to avoid transplanting the seedling when the soil is wet.
When your seedlings are ready to transplant outside (after the last frost), move them to an area for hardening-off, such as a shed, garage, or porch, for about 24 hours. Hardening-off just means you are getting your plant ready for a climate change.
When planting, cut away the plastic containers so as not to damage the plant’s roots, and plant your seedlings according to the recommendations of a plant guide.
NOTE: If possible, wash the leftover plastic container pieces and put them in the recycle bin.
Source: Master Gardener Classes