|I have been told that the plants sold by Home Depot have been treated with a growth suppressant by the grower prior to shipping to extend their
|I'm not sure where you got your information, but I don't think it's accurate. Plants are grown locally and delivered to Home Depot garden centers at the peak of health (the grower's reputation is at stake!). It wouldn't make sense for a grower to use a growth inhibitor on plants. If the plants won't grow, gardeners won't buy them! Many times lack of growth is weather related or has to do with exposure to sun/shade. But, most often poor growth has to do with soil conditions. Even though you feed and water regularly, if the roots of the plants have trouble penetrating the soil, the plants will be stunted. To avoid this in the future, take the time to amend the planting bed with compost or other organic matter prior to planting. Spread 3-4 inches over the top of the soil and dig it in to a depth of 8-10 inches. This is where the roots of most annuals and perennials will grow. Amending the soil will loosen it so the roots can penetrate deeply, the organic matter will enrich the soil by releasing nutrients as it breaks down, and it will help hold moisture near the roots of your plants. Hope this clarifies things for you and hope you have a fantastic garden.