How to Direct Sow with Worm Castings

by Jordan Mara May 31, 2022

This blog post is a subsection of our Worm Castings 101 - Everything You Need To Know guide. In the 101 guide we cover multiple topics about worm castings, so if you'd like a more thorough walk through of what worm castings are and what they have to offer then click through to read more!

Are you wanting to spend more time in the garden this Summer, but not entirely sure how to turn seeds into beautiful plants? It was only a few years ago I was in the same shoes - dumping packs of seeds and hoping for the best. But, through a few years of experimenting I've learnt which factors are most important to successful Direct Sowing. So in hopes of saving you a few years of trialing, today I'm going to share my tips to Direct Sowing and why worm castings are so beneficial to the process!

What is Direct Sowing?

Direct sowing is a term used to describe the action of planting seeds directly into the garden beds, rather than starting them indoors under the grow lights and later transplanting them into the garden.

As such, one benefit of direct sowing is that it can save you time and money by eliminating the need to purchase the supplies to start seeds indoors.

Additionally, direct sowing can help reduce the risk of transplant shock, which can occur when plants are moved from one environment to another. If you're thinking of trying direct sowing this season, be sure to do your research to understand the key factors to success and how it differs to indoor seed starting!

Arugula is a great crop for direct sowing because of its hardiness and quick growing cycle!

Direct Sowing vs Indoor Seed Starting

There are three specific scenarios when I will elect to direct sow seeds instead of starting seeds indoors under the grow light:

Fast Crops: Certain crops, such as Radishes and Spinach, have a growing cycle of only 30-60 days until harvest. Because of how fast their growing cycle is, it's easier to simply direct sow them into the garden rather than starting them indoors, potting them up, hardening them off, and transplanting them into the garden. Save yourself the time and direct sow these fast crops!
Rooted Crops: Other crops, such as Carrots, Parsnips, Turnips, and more, have a distinct tap root. This tap root is going to quickly shoot down as deep into the soil as it can rather than staying shallow and branching out. Because of this, if it is in a seed cell under grow lights it will hit the bottom of a large 3.5" seed cell within 10-14 days. As this occurs, the vegetable is more likely to grow in an irregular shape, opposed to the straight and long shape we're used to seeing.
Forgot: And lastly, every season there are certain seeds I forget to start! For those that take a longer time to mature and harvest (such as tomatoes, peppers, etc.) I will simply buy seedlings. But those that have faster growing cycles I will simply direct sow the seeds into the garden. I know we've all found ourselves in this position before!

What seeds should you Direct Sow?

If you have read our guide on Hardening off and Transplanting, then you know the outdoor garden is much more intense and variable than the indoor environment. The temperature will fluctuate significantly, wind will dry the soil more quickly, and the sun is about 10x more intense than our indoor grow lights.

Because of this, we want to start seeds that are going to be more hardy and able to withstand this intensity and variability, while keeping our more fragile plants (such as peppers and squashes) for the indoors and transplanting.

Furthermore, we need to wait until the soil is warm enough for seeds to germinate for direct sowing. Because of this, it's best to direct sow our fastest crops while giving the slower growing crops a head start by starting them indoors either a few weeks or months earlier.

8 best crops to direct sow

A few of the best crops to direct sow include Radishes, Arugula, Carrots, Beets, and more!

This combination or direct sowing and indoor seed starting will give you an abundant and much more productive garden than direct sowing all seeds.

When do you Direct Sow seeds?

For seeds to successfully germinate, they need to be in a warm and moist environment. As such, the timing will vary for each of us depending on our growing zone. To determine when to direct sow seeds for yourself, simply follow these steps:

Seeds: Determine the seeds you want to start. I always recommend growing what you love and that will bring you joy!
Growing Zone: Search the name of your city and Growing Zone (i.e. Vancouver Growing Zone). This will tell you which growing zone you're in (i.e. Zone 8b).
Planting Chart: Search your growing zone and the words Planting Chart (i.e. Zone 8b Planting Chart). You will likely come across multiple planting charts for your Zone - pick your favorite!
Plan: Go through the planting chart and look up each seed you want to start and make note of its recommended starting date. And voila - you now have a plan for when you'll be starting each of your seeds!

planting chart from west coast seeds for direct sowing

If you're gardening in Canada, then West Coast Seeds has an amazing set of planting charts and you can find yours here.

Tips for Direct sowing

So with your seeds on hand and direct sowing dates determined, how do you actually get them started? Here are a few of my favorite tips that help me get nearly a 100% germination rate:

Compost

Spread 1-2" of fresh compost across the entire bed. This will supply nutrients for the plants to grow big as well as both microbial life and organic matter for slow release nutrients.

Spacing

Use our space planner for spacing recommendation for each seed (i.e. Kale = 1 per square foot, Basil = 4 per square foot, Carrots = 9 per square foot). Utilize either a spacing square or a Hori Hori Knife to quickly and accurately space your plants.

Depth

Make a divot about 1cm deep at each spacing interval for the seed you are starting. This ensures the seed will be lightly buried - but not too deep beneath the surface.

3 Seeds Per Space

In each divot, place 3 seeds. This gives you a higher likelihood that every space will end up with a plant in it. If multiple seeds germinate and begin to grow, you can thin down to 1 seedling after 14-21 days.

Worm Castings

Once the seeds are in divot, cover them with about 1cm of Pure Worm Castings. The magic of Worm Castings at this point is that they have INCREDIBLE moisture retention which the seeds need to germinate. As such, you'll see a higher germination rate when using worm castings at the point of transplanting.

Water

Once covered, thoroughly water not only where the seeds were planted but the entire planting space (i.e. the entire container or raised bed).

Mini-DIY Greenhouse

Lastly, if possible place a Mini DIY greenhouse over top of the planting space. This will both increase the soil temperature as well as block the wind from drying out the soil. Furthermore, once the seeds germinate this will protect them from any critters looking for a mid-Spring snack!

Why Worm Castings are so beneficial to Direct Sowing

Worm castings are my secret to getting such a high germination rate.

One of the most talented horticulturalists I know would cover her seeds with vermiculite because it retains water so well. However, she shifted to utilizing worm castings because it not only has incredibly high moisture retention, but because it has the added benefit (that vermiculite wouldn't) of providing microbial life and biology directly around the seed as soon as it germinates.

As a result, you get not only incredible moisture retention but also microbial life interacting with your germinating seed from the moment it sprouts which will result in it growing bigger, more lush, and more resilient to pests and diseases.

direct sowing with worm castings experiment

In a recent experiment I started two sets of arugula seeds in a store bought seed staring mix. But, I covered one set with worm castings and even within 14 days more had germinated and they are already growing significantly larger, more green and lush!

What do you do after Direct Sowing?

Once you have direct sown your seeds, there are a few important next steps to ensure your seeds both germinate and thrive:

Watering

Both the sun and the wind will begin to dry out the area you just planted. And for the seeds to germinate, they need to be consistently moist. To determine when to water next, place the back of your hand on the top of the worm castings. If they're still moist, you don't need to water. If you don't feel any moisture, give the seeds their next watering.

My personal approach here is to use a sprayer hose and to spray the area for 10 seconds, go to another area while it soaks in, and then return for another 10 second watering spray.

using the back of hand to test moisture level

Thinning

As the seeds germinate and poke through the surface, it's likely that you will have multiple germinate in each divot (recall, we planted three seeds in each divot so it's possible to have as many as three plants in each divot).

Between Day 14-21, simply thin each divot to one plant. You can do this by either using pruning sheers or by pinching the stems of the plants you're removing.

Fertilizing

After thinning, now is the time to apply an organic fertilizer such as our Superfood or Rooted Food. I fertilize around Day 14-21 because the seed shell actually contains enough nutrients for the plant's first few weeks.

However, as it begins to put on its first true leaves and enter the growth phase, it's the perfect time to give it a good feed of nutrients.

I simply sprinkle 1tbsp of the organic fertilizer per square foot that I have planted. For my leafy greens (i.e. Arugula, Kale, etc.) and flowering plants (i.e. Tomatoes, Cukes, etc.) I use our Superfood. For my rooted crops (i.e. Carrots, Beets, Turnips) I go with our Rooted Food to provide them a little extra phosphorous for the root development.

applying organic fertilizer 14 days after direct sowing

If you’re looking for an easy and organic way to improve your seed germination rates, look no further than worm castings. By covering the seeds with just 1cm of worm castings, you'll not only increase water retention but also nutrients and microbial in the area directly surrounding your soon to be plant baby! Ready to try it out? We ship our worm castings across Canada - buy now and see the results for yourself!