The turn around time for such plants really depend on the variety of nutrient and conditions in the planet. The more variety flowing around the more resources the biologists have at their disposal. The gene-gineers will be creating several varieties intent to create an ecosystem and economics. In the course of a Solar Year and enough resources, a planet like mars (barren, thin atmosphere, few resources and with little light) would have several nurseries of the plant itself.
Plants and Biological tools go as far as being part of the underground infrastructure. Living cement can help slowly reinforce underground infrastructure and naturally seal cracks and fissures. The same cement can be a medium for underground emergency lighting, life-support (air, heat, water etc.), and more farming application when there are veins of useful material.
Plant tools have the ability to create Infrastructure while the colonists are focusing their resources and energies other things. They can be left to their own devices, which an ecological plan mapped out by the gene-gineers.
Some plants can be powered, allowing powerplants to boost their growth and accelerate the process.
IMTU, in 2170CE the very active Terraforming of Venus is thanks to aggressive plants that are designed to trap dense atmosphere into a solid and liquid form. Because of how exponential plants can grow, it has been almost a hundred years of bio-terraforming that temperatures in Venus dropped by half and density by also as much. The plants have shaped much of the planets surface, creating giant tendrils all around the planets as great as canyons. Venus is a giant jungle of mega flaura.
update: added is the introduction of hydrogen through mega freighters continuously supplying venus as in the Biological Approach of terraforming Venus in the wiki.
At around the same time, Mars surface is heavily terraformed with plants that try to increase the greenhouse effect on the planet. Much of the plants try to bring the heat and the energy deep underground. There are roots and runners in mars that act as underground rivers, that move resources and water in the vast underground network of the planet.
Because of the thin atmosphere, Mars is an underground colony and highly resistant to orbital bombardment. Mars is often intentionally the target of much asteriods diverted to add to the resources of the planet: injecting minerals and water for the plants to catch and feed deep into its underground ecosystem.
The most cutting edge biotech can be found in Sol, both in the colonies of Venus and Mars. many other planets are being terraformed like Ganymede, Io, and Titan but average at about half the amount of time being developed. Many planets in the terran systems have gene-geneered plant life that is as visible as Terra's.