How to Choose the Right Cell Size for Seed Trays
Selecting the correct seed tray cell size is an important factor in successful seed starting and plant propagation. The cell size determines how much space a seedling has for root development before it is transplanted.
If the cell is too small, roots may become crowded and seedlings may grow weak. If the cell is too large, valuable nursery space may be wasted.
Different plants require different cell sizes depending on their root growth, transplant schedule, and cultivation environment.
This guide explains how seed tray cell sizes work and how growers can choose the right configuration for their crops.
Introduction
What Is Seed Tray Cell Size?
Seed tray cell size refers to the volume and dimensions of each individual compartment in a seed tray.
Each cell holds:
growing medium
a single seed or seedling
developing roots
Cell size determines:
how long seedlings can stay in the tray
how strong the root system can develop
how densely plants can be produced in a greenhouse or nursery
Most commercial seed trays are categorized by the number of cells per tray, such as 50, 72, 105, 128, or 200 cells.
Common Seed Tray Cell Sizes
Different cell configurations are used for different crops.
50 Cell Trays – Large Cell Size
50 cell trays have large individual cells that allow seedlings to develop strong root systems.
These trays are typically used for:
tomatoes
cucumbers
peppers
eggplants
They are ideal for crops that remain in the tray longer before transplanting.
72 Cell Trays – Medium-Large Cells
72 cell trays are one of the most popular options in commercial horticulture.
They provide a good balance between plant density and root development.
Common uses include:
cabbage
broccoli
leafy vegetables
flower seedlings
This size works well for many greenhouse operations.
105 Cell Trays – Medium Cell Size
200 Cell Trays – Very Small Cells
128 cell trays are widely used for high-density seedling production.
They are ideal for plants that are transplanted soon after germination.
Typical crops include:
lettuce
basil
ornamental flowers
These trays help maximize greenhouse space efficiency.
200 cell trays contain very small cells and are designed for early-stage seed starting.
They are commonly used for:
microgreens
herbs
small leafy vegetables
Seedlings grown in these trays are usually transplanted quickly.
128 Cell Trays – Small Cells
128 cell trays are widely used for high-density seedling production.
They are ideal for plants that are transplanted soon after germination.
Typical crops include:
lettuce
basil
ornamental flowers
These trays help maximize greenhouse space efficiency.
Key Factors When Choosing Cell Size
Plant Root Development
Plants with larger root systems require bigger cells.
For example:
Large root plants
tomatoes
peppers
Small root plants
lettuce
herbs
Selecting a cell size that matches the plant’s root growth helps produce stronger seedlings.
Nursery Time
The longer a seedling stays in the tray, the larger the cell size should be.
Large cells allow roots to grow freely and reduce transplant stress.
Production Efficiency
Growers who need to produce large numbers of seedlings often use higher cell density trays.
High-density trays allow more plants to be grown in the same greenhouse area.
Choosing the correct cell size depends on several factors.
These recommendations help balance root space and production efficiency.
Conclusion
Choosing the right seed tray cell size plays a critical role in healthy seedling development.
Larger cells provide more root space and support longer nursery periods, while smaller cells allow growers to produce a higher number of plants in limited space.
By selecting the appropriate cell size for each crop, growers can improve germination success, strengthen root development, and optimize greenhouse production.
Frequently asked questions
What cell size is best for seedlings?
The best cell size depends on the plant type and how long the seedlings will stay in the tray. Larger plants require bigger cells, while small leafy vegetables can grow in smaller cells.
Is a 72 cell tray a good choice?
Yes. 72 cell trays are one of the most commonly used sizes because they provide a balance between root space and planting density.
What plants use 128 cell trays?
128 cell trays are commonly used for lettuce, herbs, and flower seedlings that are transplanted soon after germination.
Do larger cells produce stronger seedlings?
In many cases, larger cells allow roots to grow more freely, which can produce stronger seedlings before transplanting.