"grow capability" is correct and usable in written English.
You can use it to refer to the development and advancement of a skill or talent. For example: "The team is consistently striving to grow their capability in design and development."
Officials said the attack had actually demonstrated the growing capability of Afghan security forces.
Unmovic's Capability Mr. President, I must not conclude this "update" without some notes on the growing capability of Unmovic.
INSIDE Amazon's vast shipping centers, the company's growing capability as a general retailer is nearly invisible.
The assassination underscored the growing capability of the insurgency in northern Afghanistan, which has become increasingly unstable over the past year.
While the destruction on Thursday renewed questions about the rebels' tactic of seizing territory, their earlier victory showed their growing capability and the strain on government forces.
An escalation to more destructive vehicle-borne improvised explosive devices would indicate growing capability despite the ongoing efforts of Saudi security services".
"The shift to more complex suicide attacks demonstrates a growing capability of the local terrorist networks linked to Al Qaeda," the report said.
Whether it is the influence of foreign fighters, or the growing capability of the Taliban and another regional militant group, Hezb-e-Islami, Western officials say the insurgency in Kunduz has grown more sophisticated, mounting coordinated suicide car bombings and ambushes.
And Barack Obama has secretly given himself the power to authorise attacks designed to destroy computer systems governing the enemy's telecoms, traffic, electricity and water supply – while of course cultivating a 24/7 paranoia about the enemy's growing capability to do the same to us.
"I think there is a growing capability within our democracy, because of technology and social media, for people to find out more information, to communicate and connect with people who think like them, and for that to get a momentum to it.
