Answer: Dear Jan,
Without more information of how the soil was prepared prior to planting and subsequent feeding once the plants started to grow, it is difficult to know why the plants haven’t performed to your expectations.
It does sound as though the sweet corn may have not received the necessary nutrients in the early stages to allow the cob to mature. I can undertand why you would have then waited another few weeks for the cobs to grow, only to result in the cobs then becoming dry and hard. If the weather was particularly hot during this period and the plants didn’t receive enough moisture, then this could have resulted in the cobs being dry and hard.
I have listed below a few tips which may help you to grow your next crop this coming summer and be happy with the outcome.
Sweet Corn needs plenty of fertiliser and water to produce a bountiful crop. Organic matter needs to be incorporated into the soil at planting time. A pre-planting fertiliser needs to be applied in furrows where each row is to be sown so that the seed is not in direct contact. After thinning, you can scatter a side dressing of nitrogen fertiliser around each plant. You can repeat this treatment when the tassel first appears between the top leaves. Regular watering is needed while the crop is growing, especially in hot weather. When the tassels open out fully, they are ready to shed pollen. Overhead watering in the early morning will create a humid atmosphere in the crop to promote good pollination of the silks. Cobs must be harvested at the right time. They are ready to pick when the silks have turned brown and cobs stand out from the stem at about a 30 degree angle.
Trust you will have an excellent crop when next you plant.