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We’ve seen it time and time again. Someone will get caught in the trap of having instant gratification and choose plants for their flower garden plan that, in time, grow too big. Then a few years later …

… they’re being pulled out and discarded.

Their garden drama has turned into a tragedy!

You no doubt know of a house or two that you can barely see because the plants have grown to such a proportion that they are way out of scale for the home and property. Well, this was at the heart of that problem. 

Height, Shape and Growth Patterns of Plants

Please, fellow garden enthusiasts, proceed carefully and choose your plants by:

  • the height they’ll reach at maturity.
  • their mature width and spread so that you can plant them with enough space around them and avoid crowding.
  • understanding their shape, another way to know how far apart to plant them.

When in doubt, err on the side of too few plants. You can always fill in later.

Crowding your plants not only ruins your flower garden plan, it increases demand on the soil for water and nutrients and can also make plants more susceptible to disease.

And plants can’t get enough light when they’re packed together too tightly, so they grow up to be weak and spindly.

Here are a few tips on height, shape and growth patterns that will help you work with each of the plant catagories.


Most annuals will grow to heights of two feet or less (be sure to check on the particular variety you’ve chosen), so they’re ideal for flower beds and borders.

They don’t generally spread, but they still need room to grow and fill out.


Perennials grow rapidly, so keep that enthusiasm at bay when you’re purchasing them. Besides, they cost less when you buy them smaller.

Once established, perennials may need to be divided every year.
Plant them in clumps and allow groups to drift into each other for the best effect.

For estimating purposes, you can allow five plants for every 10 feet in your border. But before you actually make the purchase, be sure to check the plant’s mature spreading width, as some will grow three feet across and others only three inches.


Generally, the taller the winter-flowering bulb, the deeper it should be planted in the ground.

Watch out because some bulbs, like lilies, will spread wider with each season.


Long-term growth patterns for herbs depends on whether they are annual or perennial:

  • Annual herbs don’t spread very much because they don’t live long enough.
  • Perennial herbs can spread so much that they take over your garden. Woody perennial herbs, like rosemary, can grow tall in warm climates.

Vines and Ground covers

By nature, vines and groundcovers can grow robustly. Some grow up to 30 feet in a season – they virtually grow right before your eyes!

For areas near lawn, or if you have limited space, choose a slower-growing variety.

Remember that something labeled ‘ground cover’ in a plant catalogue may not necessarily grow low to the ground. That’s another reason to check the height at maturity of the plants that you purchase for your flower garden plan.

Ferns and Ornamental Grasses

Ferns and ornamental grasses can grow and spread quickly.

Ferns: Ferns come in all shapes and sizes. With some ferns, rhizomes creep along just beneath the soil surface, sometimes quickly branching. The branching type can spread over a whole hillside. Others will develop more slowly in clumps.

Ornamental Grasses: When considering perennial ornamental grasses for your flower garden plan, be sure to look at what the final size will be, because a mature plant may have a low grouping of leaves in the spring and then by summer or fall have a six-foot spray of flowers. If you plant one of those by your mailbox, you’ll have the postman refusing to deliver your mail through the jungle!


Home Garden Tip: Be sure to vary the height and shape of plants in your flower garden plan to create interest. In general, reserve the back of your beds for the tallest plants, working your way down to the shortest to use for borders. But with flower garden ideas, like life, sometimes the rules can get bent a little. So be adventuresome! Try using plants with a strong vertical shape, such as irises and some grasses, to pop out of neighbors with lower mounding masses, such as Lantana. This can bring a delightful relief to a staged ‘school yearbook picture’ syndrome.

Shrubs and Trees

‘Shape’ is a particularly important concept to understand when incorporating trees and shrubs in your flower garden plan. This concept will not only help you with the practical functions of your plantings such as providing shade, privacy or windbreaks, but also will help with the look and feel you want to achieve.

Shrub shapes are categorized as:

  • Upright
  • Prostrate
  • Mounding

Tree shapes can be:

  • Round
  • Flat-topped
  • Conical
  • Horizontal
  • Columnar

You can use these shapes to add interest and create special effects in your flower garden ideas. For instance, say you have a long, narrow, property. You can break it up with round shapes and tall columnar shapes to mask the long and narrow form.

Another approach is to use low plants to accent the long, narrow, form and make a design statement with the shape that you have.

The height and spread of your tree and shrub should also be considered. Be careful to check your site carefully for surrounding obstructions like:

  • Overhead utility lines
  • Roof overhangs
  • Canopies of other trees


Home Garden Tip: The outside edge of the tree’s branches is called the ‘drip line.’ Unless the area is well irrigated, don’t plant any shrubs inside that line, because the tree will compete with the shrub’s water source – and always win!

Continue on to learn how to create interest in your garden...