they look good. they still have time to sprout. maybe I should reduce the nitrogen a little. measure the EC. They have slightly burnt leaf tips from fertilizers. you could catch such a phenotype. do you drain the whole tank, or just add solution as the flowers drink.
@mikroponik, Thanks! I'm topping up the nutrient solution, and I change it every 10-14 days. The EC is currently 2.5, and there's slight over-fertilization visible at the leaf tips. I'll lower the EC slightly soon.
@KBrox, It is better to change the tank after 7-10 days. For hydro, EC 2.5 is already quite high. My water has EC 0.11 and I mix the solution to the maximum!! to EC 1.8, but usually less (depending on the variety). Measure the EC every day or every other day. If it rises, add water. If you have too much salt in the solution (strong osmotic pressure) the plants are not able to pump nutrients from the roots to the flowers.
@mikroponik, Thanks for the advice and help! So far I haven't had any fluctuations in EC or pH. I measure every other day. My water has an EC of 0.6 (very hard), I've now lowered the total EC to 2.0