Gardening 101 – Lesson Three: Types of Plants

Lessons: 1: Soil | 2: Analysis | 3: Types of plants | 4: Design | 5: Preparing for winter | 6: Design II | 7: Selecting plants | 8: Tools and How to Use them | 9: Planting | 10: Weeding and Feeding | 11: Lawns and Vegetables | 12: Armchair Gardening

All plants have their own uses. Some will fit into your garden; others won’t. So let’s take a look at the various kinds of plants you may already have in your garden or may want to introduce.

Trees

We’re lucky here in Ottawa because the City actively promotes the growth of trees. Many of us have trees planted by the City growing in our front yards, on the City’s road allowance (the area close to the sidewalk or road edge and running some feet into the front yard). Most of us don’t have to worry about taking care of these trees other than notifying the City when we have concerns.

While trees are generally tall and long-lasting, some trees have relatively short lives (poplars for example) and some are not tall at all (crabapples for instance). Many are ornamental - think of apple and cherry trees in the spring or serviceberries or dogwoods all year round. Some trees are deciduous and lose their leaves in the fall; others are coniferous and are often called evergreens.

Trees take some time to reach their full size. They supply shade and focus to the garden but because it’s difficult to move a tree, they should be carefully positioned. And, as a wonderful bonus, the average tree takes carbon dioxide out of the air and replaces it with enough oxygen to supply a family of four.

Shrubs

Also known as bushes. These are woody plants which often have more than one stem, are much shorter than trees, and are pretty compact. They can be deciduous (think of lilacs or spirea) or can be coniferous (Alberta spruce and spreading junipers are example). Shrubs reach their full size quicker than do trees and sometimes need to be pruned to keep to the size you want. It’s not impossible to move a shrub to a new location, especially when they’re young, but better to keep them in place so choose their locations carefully.

Because of their size and longevity, shrubs provide structure to the garden and can also be used to conceal less attractive items, such as composters, foundations or air conditioners. Many have flowers which provide colour and scent.

Perennials

Perennials are plants which survive our winters and begin to grow again once the weather is suitable. Generally, when people talk of perennials, they are referring to herbaceous ornamental plants used in garden beds. (‘Herbaceous’ means that they have non-woody, green stalks.) Often it is the perennials’ flowers which give the plants beauty but sometimes it is the foliage (leaves )which gives decoration to the garden. For instance, while some hostas have nice flowers, it is the foliage which are really the attractive part. Roses, peonies, irises and daffodils are all perennials grown for their lovely flowers.

Perennials, once planted, will take several years to reach their full size so it’s important to place them where they will have room to grow. They’re generally easy enough to move but digging them up and replanting will cause perennials to stop growing for a while. In general, they are the most decorative items in the garden over the long term.

Annuals

Annuals are plants which will last only one year in the garden; they cannot survive our winters. Most, such as petunias, impatience, or nasturtiums are used for their flowers but there are also a few which have terrific ornamental leaves. For instance, some newer begonia hybrids have amazingly flamboyant foliage but negligible flowers. You can buy annuals as plants which are already grown or you can plant some as seed directly into the ground. Some annuals self-seed which means that they produce seed which falls to the ground and germinate to produce new plants the next year.

Annuals grow quickly which makes them useful to introduce specific colour in specific places for a year. Often they’re used to fill in bare spots in existing garden beds. Many are used for containers which can be hung or placed temporarily in different places.

Vines

Vines are plants which will grow up vertical structures and cling to them by putting out tendrils or appendages such as suckers which will attach to the structure. Some vines simply twine to stay attached. You can use vines (such as Virginia creeper) to screen something you don’t want to look at or to cover a blank wall but there are also some vines (such as clematis) which are grown because of their beautiful flowers.

Most vines can be perennial but some are annuals which grow very quickly in one year but do not last thereafter. Some vines require regular pruning but, in general, they require little maintenance.

Groundcovers

Groundcovers, as the name implies, are plants which quickly grow to cover horizontal areas of ground. Lawn grasses are a type of ground cover but the term is more often used to refer to other plants which can be used to replace grass. Common groundcovers are periwinkle (which is a low spreading vine), sweet woodruff, and pachysandra, all plants which spread quickly and need little maintenance. Some have attractive flowers but most are grown for their foliage and spreading habit.

Besides just covering horizontal areas of earth, groundcovers are useful for stabilizing banks or sloping areas.

Bulbs

Most residents of Ottawa know that the tulip is grown from a bulb but there are lots of other plants which store their food in bulbs or similar structures. Crocuses and lilies are examples of bulbs planted in the fall or winter and which come up in the spring. Some bulbs, such as begonias, gladiolas, or dahlias, are planted in the spring for later flowering; these are known as summer bulbs.

While we generally leave fall planted bulbs in the ground year after year, most summer bulbs aren’t hardy here so will have to be dug up and stored through the winter.

Houseplants

These are often tropical or semi-tropical plants which are grown indoors, in containers. If you want to enjoy flowers or green foliage through our winters and have enough light for them, houseplants are the only economical option.

Most houseplants can go outside during the summers and used as accent plants or to supplement other plants in a garden bed.

Next lesson: Garden Design

Lessons: 1: Soil | 2: Analysis | 3: Types of plants | 4: Design | 5: Preparing for winter | 6: Design II | 7: Selecting plants | 8: Tools and How to Use them | 9: Planting | 10: Weeding and Feeding | 11: Lawns and Vegetables | 12: Armchair Gardening

Please contact the OHS or the author if you wish to republish these articles. © Ottawa Horticultural Society

Back to index of articles