Sowing melons: choosing between pots and open ground

Choosing between pots and direct sowing

Check the variety’s time to maturity and its intended location: outdoors or under cover. The SNHF recommends an early Charentais variety and distinguishes between conditions suitable for outdoor cultivation and those where cover is advised.

• In pots: start under cover if you can then keep the young plants warm, in light, and with enough space.
• Directly in the garden: wait until the risk of frost has passed and the soil is warmed. The seed starts in its final position, but later than an indoor sowing.

Melons require a sufficiently long warm season, notes Iowa State University. Direct sowing should therefore be decided based on your climate and the stated time to maturity, without automatically postponing it to the end of the season.

When to start sowing in pots?

Iowa State University suggests sowing three to four weeks before the planned outdoor planting. This is a preparation guideline, not a national date: also allow time for hardening off and reassess the planting-out date according to local conditions.

Sowing much earlier does not guarantee a useful head start. The University of Maryland warns that plants may become leggy and rootbound. Reserve a well-lit space for them before opening the seed packet.

Sowing in warmth in pots

Use clean containers with drainage holes and pre-moistened potting compost, as advised by Maryland. The RHS method is as follows:

1. Choose pots approximately 7.5 cm in width and depth.
2. Sow two seeds per pot, about 1.5 cm deep.
3. Maintain 18 to 21 °C for germination.
4. Once the seedlings emerge, keep only one plant per pot.

The RHS gives a seedling emergence time of approximately one week, as a guide. Keep the plants warm and in good light thereafter. If you have covered the pots, remove the cover as soon as shoots appear, following Maryland.

Monitoring young plants

The University of Maryland notes that window light may be insufficient: stems stretching towards it suggest the need to improve lighting. Warmth does not compensate for this lack.

Keep the potting compost moist without saturating it. Excess water deprives roots of oxygen; allowing the sown compost to dry out completely also compromises seedling development. Our sowing guide details common practices.

Sowing directly in open ground

Choose a sunny location with well-draining soil, as advised by the SNHF. To establish the crop outdoors, Iowa State University recommends waiting until frosts are over and the soil has warmed to 16 to 21 °C: this refers to soil temperature, not air temperature or an optimum germination temperature.

This university recommends a depth of approximately 2.5 cm for direct sowing. Follow the spacing instructions on the packet and thin out if several plants compete. Keep the sown area regularly moist, without waterlogging.

Hardening off and planting out

Put the pots outdoors in a sheltered spot during the day, then bring them back inside at night. Gradually increase their exposure according to the weather. The RHS reminds us that hardening off does not make melons frost-resistant.

For outdoor melons, the RHS waits for nights that no longer drop below 12 to 15 °C. This planting-out guideline does not replace the warmth required for germination in pots or soil temperature. A mild day alone is not sufficient to decide on planting out.

Protect the root ball and roots during transplanting: Iowa State University emphasises minimising root damage. For plants allowed to trail along the ground, the SNHF recommends one metre between plants in both directions. The melon cultivation guide provides further advice after planting out.