When out shopping for plants, a plant label (when written well!) will tell you how tall and wide a plant will mature to. However, there is no guarantee a plant will be that size. (One reason is lack of fully testing the size of a newly released cultivated plant, but that’s another story!)
Usually the label will give a range for the plant’s maturity size. This is because it is accounting that a plant’s mature size and shape will vary based on what kinds of conditions it is planted in. The microclimates around your garden are going to vary in patterns of sunlight, soil moisture, and wind. All of this will affect the size and shape of the mature plant.
Of course a plant will thrive in its optimal growing conditions, and it is upon us to find that perfect spot! Sometimes a plant may survive in less desirable conditions than it prefers, but it may not thrive.
Poor soil? They won’t grow as bushy or tall.
Shallow glade soil? They’ll probably grow shorter.
Really great soil for the plant? May thrive growing taller and fuller.
Shadier? A tree may will grow taller and skinnier. A shrub may grow wider and less bushy. A perennial may grow shorter, look peaked, or flop over.
Lots of sun? A tree may grow bushier, and grows vertically slower. A perennial may grow taller. A shrub may grow bushier.
Of course, there are no set rules when it comes to plants!
For example, I have several clumps of black eyed susans around my garden that traveled over from my neighbor’s garden. I’ve never planted a single one, so they chose their own microclimate! According to wildflower.org, black eyed susans should get 1-2′ tall. Let’s see how this compares!
This group of black eyed susans get nearly full sun and have reached to 44″ (3.66′) tall. From observing its timing on flowering, they are 2 weeks ahead of the other groups of black eyed susans in my garden. It looks to be thriving with its abundant flowering.
This group of black eyed susans get mostly shade. The soil is also a little drier and has a higher clay content than the other areas. They have maxed out at 22″ tall. They also haven’t flowered yet, and have much fewer flowers. I will be moving this clump to a more suitable area this fall.
These black eyed susans get partial sun. There is a lot of direct sunlight in this area, but the flowers are shaded by a shrub through parts of the day. They have reached 32″ tall, and you can see they have just started flowering.
From observing all 3 of these groups of black eyed susans, the amount of sunlight they receive is related to their heights, blooming time, and proliferation of flowers. Black eyed susans are a hardy plant and can tolerate a variety of growing conditions. This can be used to your advantage based on your specific garden and what affect you are going for.