How to Sow and Transplant Seedlings

Are you ready to fend off the winter blues by getting your hands in soil and watching things grow? Perhaps you seek to save money over buying grower started plants or have trouble finding the specific plant variety you want to grow. Or you just want the satisfaction and pride of growing your own garden plants with the knowledge of how they are grown every step of the way. So, you want to start seeds indoors, but how do you begin?

First, decide what you want to grow. For example, what vegetables do your family love to eat, and which flowers would be great to cut for bouquets?  Peruse the seed racks at Eagle Crest and check out the abundant seed catalogs. We love the Colorado company – Botanical Interests -and have heard many success stories from our customers on the viability of their seeds purchased at Eagle Crest. All their seeds are non-GMO and many are certified organic. Take care to keep the quantity of plants to a manageable number. This may be the most difficult part of your seed starting journey.

Next, figure out a schedule for starting your seeds. Most likely the goal will be for the plants to eventually go outside into pots or gardens. All seeds should not be started at the same time since some crops require a longer period to develop and some are more sensitive to cool temperatures than others and will need to wait longer to be set out. See attached for planting schedule information for many vegetables, herbs and flower seeds. Also, the seed packet is a wealth of information including seed sowing timing.

It is important to know the average last frost date where you live so that you can count backwards from that date for the proper time to sow the seeds. Frost free dates can vary widely in our valley based on elevation. As early as Mother’s Day in Glenwood Springs (in town) and as late as mid-June in the higher elevation areas of Aspen. Once you know what plants you want to grow, when they should be sown and your specific last frost date, you will be able to schedule the best date to start various seeds. It is a common mistake to get excited and start seeds too early. The result is a leggy and weak seedling that will not thrive once set out.

Now, it’s time to gather all the necessary equipment to get started. You will need an area with adequate light (or supplemental lighting fixtures), optional heat mat, access to water, seed starting soilless mix, sterile containers, plant markers and of course the desired seeds.

A south facing window may provide enough light, but care must be taken to rotate the plants to avoid leaning and to use a heat mat to combat the cool temperatures typically found near a window. A better solution is to provide grow lights that can be positioned a few inches over the seed trays and adjusted up as the plants begin to grow. Specific grow lights designed for this are available or choose a fluorescent fixture with 2 different spectrum bulbs (cool white and natural daylight) to create a wide spectrum of light. There are also some LED lights that are designed for plant growth and are a good low energy choice. An inexpensive timer attached and set at about 14 hours on and 10 off will mimic daylight hours.

Using a lightweight sterile soilless mix is essential for seed starting. Garden soil and standard potting mixes are too course, too heavy and may contain pathogens detrimental to young seedlings. Our Fox Farm Light Warrior mix or Fertilome Seed and Cutting mix are ideal. As are the small peat pellets that swell up when wet to create an instant pot and soil mix. Mixing peat moss and horticultural grade vermiculite also creates a good seed starting base.

The pots that are used can vary from specific seed starting packs to anything on hand such as an egg carton or homemade container made of paper. All must contain drainage holes, be appropriately sized and sterile. If reusing old containers be sure to thoroughly wash and then sterilize with a 10% bleach solution. Flats with a domed lid will help to keep the pots together and contain humidity which will ease germination of most seeds. Once the seeds are up and growing the lids can be removed. Consider the kits we have at Eagle Crest with packs, flats and domes included.

Heat mats, though not essential, are a helpful tool in keeping the temperature of seedlings consistent and slightly warmer than the surrounding indoor temperatures. Warm season crops such as tomatoes and peppers particularly benefit from this. Keep the heat mats on continuously.

An optional fan can increase air circulation around the plants once they are up and growing to prevent fungal diseases and toughen up the seedlings prior to outdoor planting.

You’ve now chosen the seeds, scheduled the appropriate dates and have the equipment collected. Time to start planting. Once pots are filled with the seed-starting mix place 1-3 seeds per cell of a pack or individual pot (the weaker ones should be removed once they are growing). Consult the seed packet for proper seed depth but most small seeds will be just on the surface, while larger seeds should be covered with a thin layer of seed mix or vermiculite. Remember to plant a few more pots than you think you will need in case of some loss but don’t overdo it. Make sure to label the pots with the seed variety planted and the date sown.

Keep soil moist during germination and place the dome over the germination trays to keep the humidity high during this time. However, avoid overwatered soggy soils to prevent rotting roots. A good watering technique is to water from below by placing the plants in a tray of water or the sink letting the soil get saturated and then removing them from the water. Place tray on heat mat (if you have it) and wait for it…

Once the plants are up with at least 1-2 sets of true leaves (there will first be a set of seed leaves), remove the humidity dome and set up lights just over the trays. You can begin fertilizing biweekly with a weak solution of water-soluble fertilizer (less than 50% of the recommended dilution rate). We like Fox Farm Big Bloom or Liquid Seaweed if you want to grow organically. Fertilome All Purpose Water Soluble Plant Food is also a good choice. Keep watering regularly-check the plants daily. Using a fan to increase air circulation around the plants and toughen them up is a good idea at this stage. Just remember that this may dry the young plants out quicker. Remember to adjust any grow lights so that they stay a few inches above the growing foliage.

Some crops will develop roots quickly and will require transplanting into a slightly bigger container before they are ready to go out.  When it is time to set the plants outside (consult the seed packet) it is best to get them acclimated to the outdoor conditions by setting them outside in the shade during the day and bring them back in at night for several days. You want to toughen them up gradually before they go to their permanent home in the garden.

The process of growing a full crop of vegetables, herbs or flowers from tiny seeds never ceases to amaze. Take pride in the role you played in extending the length of our short growing season.

Download Indoor Sowing Guide Here >