Now that your seeds have been planted, we need to maintain them to ensure that we get the best growth possible in the short time that we have before school ends.   

When the seedlings are about 4 weeks old, you will add fertilizer.  We use Peters plant food liquid fertilizer, but almost any liquid plant food will work.  The mixing ratio for the Peters Plant food is 1 Tbsp to 1 gallon water, and should be applied every 2 weeks. 

When the seedlings are about 6 weeks old, you will begin the process of acclimating the seedlings to salt water. Using Instant Ocean as the salt, increase the salinity of the water in the trays the plants sit in by about 5 ppt every week until you reach about 25 ppt. Once the salinity is at 25 ppt, maintain it there until the seedlings are planted. 

The following table is a handy guide to increasing salinity.

Salinity (ppt)Instant Ocean to add to 1 Gallon of Water
54 tsp
108 tsp
154 tbsp
205.5 tbsp
257 tbsp

Keeping accurate records of plant growth and care can help ensure the best growth and is a great way to involve students. Monitoring can revolve around class schedules, and is best done at least once a week. 

Things to include in the monitoring:

  • Planting date
  • Germination date
  • Fertilization date
  • Salt acclimation begin date
  • Weekly growth measurements
  • Weekly watering schedule
  • Weekly salinity meaurments
  • Any problems

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