The Hebrew word for "to declare blessed" is barak, and it occurs four times in the Genesis account with regard to creation.
Gen. 1:22 - God spoke a blessing to them (the sea creatures and the winged creatures).
Gen. 1:28 - God spoke a blessing to them (man and woman).
Gen. 2:3 - God blessed the seventh day (no speaking involved as 'day' is a word, not a living thing.)
Gen. 5:2 - God spoke a blessing to them (the male and the female he had created earlier).
Perhaps there could be significance in the fact that it is not always necessary for God to speak a blessing in the hearing of man in order for the blessing to be given? The Genesis account says God blessed the seventh day, but he did not appear to voice that blessing. As a day (any and every day) is not a living entity, it would be in a different category to the sea creatures, the winged creatures, and the humans God had created.
Yet man needed to know that God had blessed those creatures that were created before him, otherwise how could that information get into the written record? That would include knowing the seventh day was special, so although the account does not state that God told Adam about blessing the seventh day, surely he did?
That still leaves unanswered the question of why the account makes no reference to any blessing for the land creatures. However, they clearly were blessed. They had been blessed with life, and all the food and water they needed to live well, and they obviously had the ability to procreate. They also had the blessing given to them by God of Adam choosing names for them. They were not objects; they were named, living creatures.
There are many times throughout the Bible where God's blessing became apparent, even if the recipients were unaware that God had blessed them in a particular way, so this is why the answer might be that it is not necessary for God to speak a blessing in order for that blessing to result. Sometimes the blessing of God is only realised with hindsight. And sometimes people don't even know God is blessing them, although others, with eyes to see God's blessings, can spot it.
So, my answer to the question is that creatures made on the 6th day were blessed, even though the record does not say that God spoke blessing to them.