How to read a seed packet: depth, spacing and days to harvest

First, find the action and the starting point

Before opening the packet, answer two questions: where will you sow, and what event starts the harvest countdown? “Direct sow” means sowing in the growing position. “Start indoors” means raising seedlings in containers before moving them outside. Follow the instructions for your crop and variety; a sowing date printed for another region may not suit yours.

Keep the packet. You will need its variety name, spacing and harvest guidance after the seedlings appear.

A practice label, not a crop recommendation

The label below is an invented teaching example for an unnamed leafy vegetable. Its numbers are for the exercise only. Use the figures and conditions on your own packet when growing a real crop.

Read depth and spacing in different directions

• Depth goes down: 1 cm is how far below the soil surface to sow this example seed. It is not a gap between plants. Follow any special surface-sowing or light instructions on a real packet.
• Spacing goes along the row: seeds begin 2 cm apart. “Thin to 10 cm” means remove excess seedlings so the plants you keep stand 10 cm apart. Seed spacing and final plant spacing answer different questions.
• Row spacing goes across: the next parallel row is 25 cm away. It does not mean leaving 25 cm between every pair of plants in the same row.

Turn that label into a small plan

For the exercise, sketch two parallel rows; the drawing does not need to be to scale. Label the gap between rows “25 cm”. Mark example seed positions along each row and label their spacing “2 cm” and their depth “1 cm”. Add a second note: “After seedlings establish, thin to 10 cm as directed.” This keeps the sowing pattern separate from the final planting pattern.

For a real packet, check the variety’s instructions for when and how to thin. If it gives only one unexplained “spacing” figure, look up the supplier’s full instructions before treating it as seed spacing, final plant spacing or row spacing.

Keep the two clocks separate

Germination time describes how long sprouting may take in suitable conditions. It is not time to harvest. Temperature, moisture and other growing conditions can change what you observe.

Our fictional label says 45 days FROM SOWING. If you sow on day 0, the harvest estimate points to around day 45. Do not add another 5–10 days: those days already fall within this example’s sowing-to-harvest period. Inspect the crop’s readiness rather than expecting a guaranteed harvest date.

Real suppliers do not all describe maturity the same way. Some count from sowing, some after germination, and transplanted crops may count from planting out. Find the stated starting event on the packet or in the supplier’s variety notes. If it is missing, ask the supplier; a bare “60 days” cannot tell you which clock to use.

When a packet counts from transplanting, the time spent raising seedlings indoors comes before that countdown. “Start indoors six weeks before planting out” is a scheduling instruction, not six weeks to harvest.

Use the worksheet, or copy this note

Use one worksheet per packet so its instructions stay together. Copy the harvest starting event as well as the number of days; leave unclear fields blank until you can check them. You can also write the same information in a notebook:

• Crop and variety: ___. Direct sow or start indoors: ___. Local sowing conditions/date: ___.
• Sowing depth: ___. Initial seed spacing, if given: ___. Final plant spacing: ___. Row spacing, if relevant: ___.
• Expected germination: ___. Harvest estimate: ___ days from ___. Actual sowing date: ___.
• Anything unclear: ___. Check the supplier’s instructions before filling that gap with a guess.

What this guide is based on

University extension guidance explains packet fields, sowing and thinning; the seed supplier’s timing guide shows why the starting event matters. This article’s label, planning exercise and worksheet were created for Coru. They are illustrations, not results of a growing trial.

Sources & further reading

• University of Saskatchewan — Reading a seed packet
• University of Georgia Extension — Starting Plants From Seed for the Home Gardener
• Holmes Seed Company — Understanding Degree Days & Days to Maturity
• Washington State University Extension — Propagating Plants from Seed