Should you start with young plants in trays or blocks?

Picture the start of your planting season. The greenhouse is spotless, fresh substrates line the aisles, and trays of young plants are ready to grow into this season’s crops. It’s the perfect setup for success. Right?

We’d like to challenge that in this blog post.

Why tradition isn’t always right

Traditionally, most growers start with trays of small plants. Trays are efficient, easy to handle, and allow for uniform growth. Seedlings in trays are neatly separated, making them simple to water, fertilize, and transplant. This approach streamlines logistics, reduces labor, and lowers startup costs.

However, today we’d like to argue for starting with plants in soil, peat or stonewool blocks instead of in trays. This strategy can increase your yield and your profit. Here’s why.

Seasonal considerations

Before we dive in, it’s important to mention that this blog mainly deals with your summer planting season. Smaller plants with only one truss need just 10% of the light that larger plants need. If you start in the winter, particularly in colder climates like in the Netherlands, you won’t have enough natural light for larger plants. You can use artificial light, or opt for smaller plants that will grow into larger ones by spring.

Summer provides too much light for smaller plants. You’ll find yourself focused on protecting your small plants rather than nurturing them for a fruitful season.

Therefore, for maximum efficiency in summer, work with bigger plants that will thrive in the bright seasonal light and lead to higher yield.

The impact of plant size on final yield

Starting with larger plants can extend production by 5-7 weeks. Production periods are roughly 40 weeks, therefore you’ll increase overall production by about 15%.

You might read that and wonder, “but don’t larger plants start as smaller plants? Why can’t I just start with smaller plants and delay my production period by 5-7 weeks and then continue harvesting crops for an extra 5-7 weeks at the end of the season?”

It’s true, larger plants start as small plants, but you don’t want these smaller plants taking up space in your greenhouse. Smaller plants demand intensive care. You’ll be preoccupied with ensuring the plants are growing at the right rate, growing the right number of leaves, and ensuring there is a balance between leaf and fruit growth. If you don’t do a good job, you might end up with irregular crops that vary in size or with flushy, inconsistent production. These smaller plants thrive better in a nursery environment specifically created to meet their needs.

Even if you do choose to go this route and nurture small plants until they turn into larger plants, you cannot extend your production period to yield more fruit. When your regular season ends, you’ll need to clean out your entire greenhouse to prepare it for the next season. You won’t be able to wait 5-7 weeks while these plants give their last fruits.

When you start with larger plants, you maximize the production capacity in your greenhouse.

Growing technology for bigger plants

Larger plants are generally easier to care for. They are less sensitive to environmental changes, diseases, and other factors, meaning you’ll spend less time nurturing them in your greenhouse. They do, however, require more technology and equipment.

Here are a few things you might want to invest in:

• Sticks and seedling clips: As trusses grow longer and heavier, they may not be able to support and stabilize themselves. You need sticks and seedling clips to keep the plants growing upright so they don’t fall, break, or tangle. Choose sticks and clips sized for the full expected growth of your plants.
• Climate control: Based on your environment, you might need equipment for climate control. This could mean screens, artificial lights, cooling equipment, and other tools to ensure optimal conditions for growth.
• Growing Floor: A growing floor ensures a flat underground and that all blocks receive equal amounts of water. The floor will also include piping for irrigation run off.
• Bumble bees: Bumble bees may not be technological, but they can be a wonderful tool for pollinating in your greenhouse. Bumble bees are more efficient than manual pollinators and can improve fruit quality.

Testing in your greenhouse

If you usually start your season with smaller plants and want to try our recommendations, try testing blocks on a small scale first.

Any change you make should be tested in a small greenhouse so it won’t affect your overall production if it doesn’t work out. Use a small greenhouse to test growing plants from blocks. Track the amount of labor these plants require and the yield you get throughout the season. Compare this with your yield per square meter in your regular greenhouse.

Is there a significant difference? You can also try out different techniques, technologies, and other plant sizes in your test greenhouse to see what produces the largest yield. Once you’re confident in these results, you can apply these practices to your entire operation to experience an increase in yield.

Yield and cost management

Larger plants deliver greater yields, but they also have a larger startup cost. It is important to manage your business with this in mind. You’ll need to save some of your profits to support your next season, however this initial investment will pay off.

Make decisions based on yield, not only on cost. You don’t want to miss an opportunity to grow your business. If you’re ready to maximize your potential, start testing larger plants in blocks next season.