How To Grow Seedlings - Germinating for Success - Bootstrap Farmer

Germinating for Success - The Ultimate Bootstrapper's Guide


Germinating for Success - The Ultimate Bootstrapper's Guide

It’s A New Season!  

The start of the new year awakes something within a farmer. It’s official now! Days get longer and that means only one thing: spring is just around the corner. The start of the year is a great time go prepare and plan your crops and gather needed equipment, tools and other resources. One of the first questions that comes to mind when thinking about seed starting might be “whatcha going to use and how you going to use it?” Here, we've assembled a guide with information we have found valuable in hopes that it will offer value for others preparing to start seeding this new year. . 

Choosing the Right Material for You

When thinking about starting transplants for your garden or farm, there are  number of options to consider regarding materials to use when starting your seedlings.

The two most popular ways are:

  1. Create plugs from cell flats
  2. Use a soil block maker to create soil blocks in a Soil Block Propagation Tray.

There are some advantages to using soil blocks; you don’t have to buy cell trays and the transplants usually develop a quality root mass allowing easy transplanting. However, it takes some time using the soil block maker to become familiar with the right material and dampness to use so that the blocks form just right. We have also found that they do dry out quickly and require extra TLC

The other popular way to create transplants is through using cell flats. There are many different types of cell trays to use, most of them quite flimsy, easily cracking and breaking. We had such a finding trays that didn’t end up in a landfill after a single use, that we began having our own Extra Strength Cell and Flat Trays manufactured. These trays have allowed us to buy what we need and then reuse again and again. It is important to note that you will want to wash your trays in-between crops to avoid any unwanted fungus or bacteria issues. Because these trays are intended for multiple uses, it’s good not to forget this.

Picking Cell Insert and Trays

When deciding on a cell flats we find it useful to consider our growing ambitions (number of needed transplants) and speed of growth for the different varieties.

If you’re going to be transplanting hundreds and thousands of transplants, you’ll want to find cell trays with as many plug holes as possible. We find the 200 cell inserts to be very economical for what we do. However, if you use cell flats with a lot of holes, they are naturally smaller in size, meaning that timing is important so that they will not become root-bound. They will also dry out quicker than larger cells, so it is good to keep a close eye on them. The 72 cell inserts are extremely popular andThe Market Gardener (by Jean-Martin Fortier) recommends this size for many varieties. They allow a little more flexibility (you can wait on transplanting a little longer) than with the 200 cell inserts.  

The speed (or rate) of growth for the variety of vegetable you’re growing is an important factor to consider. When growing vegetables (like peppers), which take more time to reach a transplantable stage than other varieties, adequate growing space will be needed. Starting these in 32 cell inserts or a 50 cell inserts would be a good option for these and most crops that require additional growing time. 

Preparing Cells for Seeds

We fill our cell trays with a dampened media of coco coir, perlite & vermiculite. There are a number of different media to use for this, but this works for us. Wetting down the media before filling the cell allows all the cells to receive adequate moisture. When adding the media to the cells, make sure that it covers the tops of all the cells. We like to take another cell tray and stack it on top lightly packing the media into the cells (see images below), but you can also lift up the cell flats a few inches and then drop them, which helps to back the soil in a bit. (It is helpful to leave a slight lip at the top of the cell to catch water for those top watering.)

Packing Cells

Here you can see how we use the bottoms of our 200 cell flats to pack cells

200 Cell Flat


Seeding the Cell Trays

Once you’ve got your cell plug flats or your soil blocks made, it’s time for seeding! There are a number of tools available to market growers allowing them to speed-up the seeding process. The vacuum seeder is a tool that drastically speeds up this step. There are small hand-held seed dispensers that are widely available and these work quite well. Sometimes, we just use the ole finger and thumb technique too. However you decide to seed your trays, choose a system that is right for you.

After the seeds have been dropped into the cell flat trays, cover lightly. This will make sure that the seeds receives adequate moisture and is given the best chance at germination.  

Germinating for Success

When germinating seedling, starting them in a controlled environment (inside) allows for optimal moisture retention and more uniform germination.  

For the first two days after the seedlings are sown, we keep the trays covered to maintain enough humidity for the seedlings to ‘pop.’ Maintaining moisture levels allows for more uniform germination rates. There are a few methods we have found to be helpful when controlling moisture levels after seeding. Using other 1020 Trays to cover over top of our cell insert and tray or using humidity domes (below bottom), allows us to maintain consistent humidity levels.


Keeping these germinating seedling indoors for the first few days allows complete control of the temperature, which can be a significant factor affecting germination rates. Inside temperatures between 60 and 80 degrees Fahrenheit we’ve found to be optimal for quick and uniform germination.   

Time to Start Growing

Through paying attention to the elements that all plants need, light, moisture, temperature, and time, we can make sure that we are giving our plants the best chance for success. 

We usually remove the germination cover by the the 3rd or 4th day, and the seedlings are placed directly under the grow lights or in a coldframe/nursery.  If using grow lights, keep the light only a few inches above the seedlings. Grow lights that are too high above your seedlings will cause them to stretch excessively.  If using incandescent bulbs, it is a good idea to place the lights a few extra inches higher to avoid any stress from the heat given off.

For the next 4-5 days your seedlings will remain under the grow lights until they are a bit stronger and can handle wider temperature fluctuations.

Now that the seedlings are emerging from their moist germination stage, it is important that we provide adequate moisture (but not too much).

Watering and Caring for the Seedlings

When watering your seedlings from above, make sure to do at least two passes with your wand (or nozzle) using a gentle setting. Nozzles that have many holes in them usually provide a very gentle and even spray. The first pass gets the soil moist while the second pass allows the water to get further down into the soil. The soil should be kept moist but not too wet. ‘Damping off’ is a disease that affects young starts when the soil is too wet.

When using an outdoor nursery or cold frame, it is good to be aware of the areas that get the most direct light. These areas dry out cell trays more quickly than others and you may need to water them more frequently.

The weather also plays a role in the amount of water you may need to use;  If days are cloudy, less water is needed than with hot days. Being aware of weather conditions that may become extreme enables you to take additional precautions in order to avoid loss.

Watering seedlings from underneath is also a way to keep the seeds moist, especially during the heat of the summer months or those times you need to buy yourself some time. We’ve found that through using a 1020 tray as a base for the cell flats to sit in, we can put water into the bottom 1020 tray and it wicks up into the cells. Again, as with top watering, monitor the amount of water given to avoid any issues.

How Long Before Transplanting?

The time it takes to grow the seedlings in the nursery or cold frame varies based off of the type of crop (greens are ready much sooner than tomatoes), and the materials you’re using. If you’re using the 200 cell flats for lettuce, you’re going to want to transplant the seedlings not long after they have grown their first mature leaves. The temperature of the nursery also factors into how fast your plants grow. Make sure to keep a close eye on your plants during this stage so that they don’t become root bound and stressed.

For some varieties that take longer (and are larger plants), like peppers and tomatoes, it is not a bad idea to use the potting up technique (giving the plant a larger container to grow in). For market growers on small plots, using this technique is important because it allows for more open bed space time. The aim of the game is to get the transplants into the ground when they can be most productive. If you can wait another two-three weeks through potting up transplants, that’s an additional two-three weeks your beds can be producing other crops.

Time for Transplanting

When preparing the plants to transition from the nursery into the garden, it is a good idea to ‘harden off’ the transplants. This means giving the transplants a little taste of what the outside elements are like so that they don’t experience too much shock. This is especially important to do during the shoulder (spring and fall) seasons when temps can still get quite cool at night. We like to set out plants outside on a tables (or something that they can sit on sturdily), five to seven days before transplanting them into the garden. During the night, if the temperatures get too cold, we can move them back into the cold frame/nursery or cover them with row cover. The idea is that you’re preparing the transplants for the ‘real world.’  

As your seedlings are getting hardened off and ready for the soil, keep a keen eye on the weather. Doing a morning planting in the garden during sunny days can completely wipe out seedlings you’ve taken time and energy to nurture. A good rule of thumb is if you need to plant during sunny periods, planting in the afternoon/evenings will give your babies the best chance to thrive. If you have days that will be overcast and cloudy, planting in the morning works great.

When taking the cells out of our cell flats (especially the larger numbered cells), we find it most efficient to pop out the cell plugs before taking them to the garden beds. We simply get a small stick or something to poke through the hole at the bottom of the cell and gently pop out the plug.  Once the plants are in the ground, watering them into the ground allows the plant to begin to establish itself. We find it helpful to wet down the cell flats before transplanting them as the garden soil will often pull moisture away from the transplant plug. Making sure the transplants are moist when entering the ground and making sure to water them in ensures the plants have a good chance to achieve their growth potential.    

We would love to hear any additional thoughts or questions!  Please feel free to comment below or you can contact us directly.


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