He who sows densely harvests scantily; he who sows lightly harvests plenty.
— French proverb
ANY DISCUSSION OF DIRECT SEEDING must begin with the acknowledgement that for the purposes of market gardening it’s generally more efficient to transplant seedlings than to direct seed. Transplanting ensures perfect density, allows the crop a considerable head start over the weeds, and greatly reduces the amount of time spent weeding. It’s also much easier to ensure optimal germination when operating in a controlled environment. However, there are some crops that just don’t transplant well and need to be direct seeded.
Despite the drawbacks associated with direct seeding, it is a faster, easier, and less expensive process than growing seedlings indoors. In this chapter, I will discuss the many different tools and techniques that can be used to simplify the practice of direct seeding. To begin with, two important things must be understood.
Firstly, it’s important to ensure a good germination rate for high-yield production. Starting with quality seeds should be a given. Nothing good can come out of seeds with a poor germination rate, so I highly recommend acquiring them from professional seed producers with proven track records. Properly storing the seed stock throughout the season is also very important. Seeds should always be stored in an airtight container and placed in a cool and dry environment. To ensure that the seeds we rely upon are always in prime condition, we try to avoid using seed stock for previous years. We manage to do so by calculating our needs as precisely as possible when placing our annual seed order.
In the garden, germination rates will also be influenced by climatic conditions, which are notoriously difficult to predict. Since uniform growth depends on soil moisture and temperature, our job is to control these parameters regardless of what happens with the weather. This is the main reason why having a reliable irrigation system is essential for the market garden. For fast and optimal germination, the soil should always be kept moist right up until the seedlings emerge. In cool weather, it’s recommended to cover the beds with floating row covers, which helps keep the soil much warmer.
Secondly, it’s important that the crops be spaced with precision for optimal use of the bed space. One easy way of achieving this is to broadcast or heavily seed, and thin the rows to the desired density later. While this can be effective, it’s not efficient: thinning a 100-foot row of carrots is laborious and can easily take two people over half a day. For the sake of productivity, it’s preferable to seed precisely and keep thinning to a minimum. This is where precision seeders, which can drop seeds at the desired spacing, come in very handy.
Manual seeders have been around for a long time, and there are numbers of different models available on the market. Finding the best seeder for the job can be a challenge, as each crop has its own distinctive seed with a specific shape, width, and germination rate. I have tried many of the hand-push seeders currently on the market and found that all have both interesting features as well as drawbacks. Apart from precision, the characteristics that I look for are ease of calibration (i.e., not spending too much time adjusting it for different seed sizes and shapes), ease of use, and price. The ones that we use at Les Jardins de la Grelinette are presented below. You will find a list of the suppliers that sell these seeders in the tools and suppliers appendix.
The EarthWay Precision Garden Seeder, also sold under the name Semtout in Europe, is a push-type seeder which drills the seeds into a furrow created by an adjustable opening shoe located at the bottom of the seed hopper. It’s driven by a belt attached to the front wheel, which turns a disc called the seed plate. When pushed, the seed plate separates and scoops up the seed before dropping it into the ground. The seeds are then covered by a dragging chain, and the soil is pressed down by the rear wheel. A handy built-in adjustable marker helps you achieve parallel rows when seeding.
EarthWay offers 12 seed plates designed for different seed sizes and in-row spacings (we use only the original 6), which can be changed in 30 seconds. Such easy calibration makes this tool a simple and efficient device to use. The EarthWay is really good for beans, peas, radishes, spinach, and beets,* but is less effective for small seeds, which often get caught in the mechanism. While it may not be the most effective unit on the market, its advantages outweigh the disadvantages, and it is the most affordable on the market. We have never replaced ours since we first purchased it many years ago, and it’s a tool I continue to recommend.
The Glaser and EarthWay seeders are very different but complement each other well. They don’t provide perfect precision spacing, beets and carrots might not grow to uniform size, but this is not a problem. Our clients don’t expect such “perfect” produce.
Like most Swiss tools, the Glaser Seeder is simple and well-designed. Rather than operating by a belt, this pinpoint seeder utilizes a ground-driven rotating shaft indented with round holes to carry the seed out of the hoppers and into a furrow. The shaft can quickly be adjusted to three hole sizes (small, medium, or large), which accommodate different seed sizes. A small brush that removes excess seeds provides further adjustment. The user can also adjust the sowing depth by changing the angle of the handle when pulling the seeder along.
Since the Glaser Seeder is very effective for small seeds, particularly round ones, we find that it nicely complements the EarthWay seeder. Its downside, however, is that it only functions properly on finely prepared soil — without rocks, clods, or chunks of un-decomposed organic matter. If any debris is present on the soil, the wheels get jammed and the seeds won’t drop. The soil surface also needs to be firmly pressed to facilitate traction. The rotary harrow we use for bed preparation creates the perfect condition for the Glaser Seeder, but a seedbed roller can do the job just as well. Because the Glaser Seeder doesn’t have a furrow closing mechanism, we bury the seeds with the back of our bed preparation rake when the seeding is done. Overall, the Glaser Seeder works well, but it requires a certain mastery and skill on the part of the user. I would recommend trying it out first on a small area to get a feel for how it works before using it on a large area.
Depth of planting affects both germination and emergence rate. A good rule of thumb is that seeds should be planted at a depth equal to their thickness, but it’s always good to refer to the information provided by your seed supplier.
The Six-Row Seeder is designed for intensive seeding and was developed with salad mix and baby greens production in mind. It’s the most sophisticated of the hand seeders we use. The mechanism is similar to that of the Glaser, except that the seed shaft is rotated by a pulley attached to two rollers, which act as wheels. These rollers greatly improve the traction of the seeder and tramp down the seeded surface. The tool also has three drive ratios that allow for different in-row spacing densities. Depth is easily adjusted by raising or lowering the front loader.
The Six-Row Seeder is good for seeding crops densely, which is useful in an intensive cropping system. We use it for mesclun mix, baby spinach, carrots, and early radish — when seeding these crops in our hoophouses.
The hoppers of the seeder are spaced 2¼ inches apart, leaving no room for hoeing between the rows, or for any weeding at all for that matter. The idea behind this design is that after two passes (i.e., up and down the bed) over a width of 30 inches, the seeder will have dispersed seeds so densely that the crop will cover the entire bed, effectively shading out potential weeds. On the one hand, this allows for very efficient use of space, but on the other hand, it requires weed-free soil—an ideal not so easy to achieve. There are different strategies to accomplish this which I will discuss in the next chapter. Like the Glaser, the Six-Row Seeder works best for small-seeded crops (under beet size) and also requires a clean, firm surface in order to function properly.
Any successful direct seeding begins with well-prepared soil. Hand seeders run most efficiently when the soil is cleared of debris, levelled, and raked to ensure the best possible seed-to-soil contact. The soil surface also needs to be fairly dry in order to avoid clogging up the seeder. If the soil sticks to the surface of the seeder’s wheels, it’s generally best to wait until the soil is dry.
Seeding in a straight line with rows parallel to one another is also very important as it allows for safely hoeing between rows before the seedlings come up. (This is especially important for weed control in slow germinating crops like carrots.) Before seeding, we mark our rows, and once the bed is seeded, we run the back of the rake over the soil to cover the seeds with a little soil, so that they don’t dry out in the sun. We then install a water line and irrigate when necessary. Our water lines are designed to irrigate two, four, or eight beds at a time, so we try to do direct seeding on multiple beds on the same day. For this reason, our crop calendar and garden plan are organized around the seeding dates for direct-seeded crops.
Nothing is more frustrating than to sow a crop only to find out a month later that the density is lower than expected. The best way to avoid this scenario is to weigh the seed packets before and after every seeding (the difference being the total weight of seeds sown in the ground) and compare this number to an optimal target density. If for some reason the seeding density is too low, we know to pass the seeder a second time. This simple verification makes it easy to detect a production problem before the crop germinates. If unsure, it’s better to err on the side of seeding too thickly than too thinly, even though this might require later thinning of the crop. Systematic record keeping is highly recommended when it comes to seeding, as this might provide explanation in the event of crop failure. The outline below provides examples of how we keep records on our farm.
When cultivating with a hoe, it’s much easier to follow a straight line than a wandering one. This is why we mark our rows. We do so by fitting a few short lengths of interchangeable plastic tubes over the tines of our bed preparation rake. Our row spacing calculation is based on the width of the hoes we use and the optimal spacing for each crop.
Radish: five rows (6" apart) seeded every 1¼ inches, using the EarthWay Seeder radish plate at a depth of ½ inch (density rate between 3 and 4 ounces per 100' bed). Cover with an anti-insect net.
* French Breakfast seeded in rain; not great.
Direct Seeding Table for Intensive Spacing
*The Six-Row Seeder comes with an instruction manual in which calibration codes are found. The letters presented here refer to these codes.
Record keeping has been especially important in determining optimal spacing and in selecting and calibrating our seeders. You can calculate optimal seeding rates for direct-seeded crops by recording the weight of the seeds put in the ground and taking note of the crop spacing later on. Standardised bed lengths simplify this practice.
* Seeding beets with the EarthWay requires heavy thinning, which is one reason why we prefer to transplant this crop.