Submitted By: Egan Davis, Principal Instructor (UBC Botanical Garden)
Spring in Metro Vancouver is a special time of year. Starting in January, bulbs are beginning to flower, winter-flowering shrubs are smelling sweetly, and birds are actively preparing for their nesting season. This glorious emergence of life continues for months with the growing promise of warm summer nights just around the corner. Being a busy time of year for gardeners, it can also be challenging, balancing creative efforts such as planting and seeding with maintenance tasks such as pruning and weeding. Is there ever enough time to get everything done? Here are some eco-friendly tips that will save you time and help you get the most enjoyment out of gardening.
Stop the Spring Clean-up
Gardens do not have to be clean! Working in the garden should not be approached like doing housework tasks such as vacuuming and window washing. Fallen leaves and other plant debris are best left to slowly decompose allowing nutrients to cycle naturally and eventually become used by plants again. This natural process engages micro-organisms, worms and insects, which in turn provides food for other microbes, insects, birds and other animals, helping to maintain a healthy, biodiverse environment. The garden is an ecological system and removing garden debris interrupts this simple cycle. Many people worry that keeping debris in garden beds will harbor pests and diseases. The opposite is true. Surface litter in the garden provides habitat for beneficial micro-organisms, native bees and predatory insects that keep pests and diseases in balance.
How can the garden look good if it is not cleaned up? It is time to change our attitudes about what gardens should look like. Perfectly cultivated black soil and groomed plants is an aesthetic that people have created. Gardeners have been conditioned to think that leaves, twigs and pine needles on the soil surface are messy. Some people might argue about the esthetics of gardening styles, but there are a few things gardeners can do in the spring to allow these essential materials to remain in the garden in a visually agreeable way.
When cutting back perennials, chop up perennial stalks into smaller bits and scatter the material evenly in the garden. Leave cut-back perennial stalks a few centimetres long to provide habitat for native bees and other beneficial wildlifes. Redistribute leaves so that chunkier pieces are in the back of the garden or hidden under larger shrubs. Move the finer textured materials to the front of the beds and into the higher profile areas. Keep the texture of the surface debris consistent for a uniform look. A good trick for accomplishing this is to lightly dress the whole bed with a sprinkling of compost or fine, partially decomposed leaves. Using these materials will provide a uniform, dark colour.
Pruning is sometimes undertaken in spring, before plant growth commences. Done correctly, pruning at this time can modify growth and encourage flowers and fruiting of some plants. Done incorrectly, spring pruning can result in an undesirable growth response, and flowers and fruit can be lost.
Before any pruning operation, you need to consider whether there is a good reason for pruning, and what season is most appropriate for the given task. Reasons for pruning include modifying growth (hedge pruning), promoting flowers or fruit (spur pruning fruit trees), maintaining health and vigor (thinning old canes from suckering shrubs), and size control. Plants that are best pruned in spring include: roses, hydrangeas, lavender and sage. For suckering shrubs that flower in spring, such as forsythia, it is best to wait until after flowering before removing old stems.
For spring pruning, it is important to understand the annual growth cycle of woody plants. Generally, woody plants grow in the spring and tend to produce flower buds in the summer. Some plants, such as roses, flower on new wood and produce flower buds that open right away. Other plants, such as rhododendrons and camellias, flower on old wood and produce flower buds in the summer that do not open until the following spring. Make sure that if you are pruning in the spring that you do not cut off the flower buds on plants that flower on old wood – otherwise you will have to wait another year for beautiful blossoms.
Plants often outgrow their intended location and this is why gardeners are faced with having to make undesirable pruning cuts to control size. This often results in a vigorous growth response that spoils the natural beauty of a plant. Pruning shrubs and trees for size control is nearly always better carried out in early summer (after spring growth has finished), but often a better long term solution to this problem is to move plants in to a new and more appropriate location.
Planting and Transplanting
Planting in the spring is the most exciting activity for gardeners. In the Metro Vancouver region, the transition from winter to spring is usually, so spring planting can happen over a long period. It is important to understand the differences in weather conditions throughout the spring and how this relates to the life cycles of plants that we like to grow.
Most perennial plants, woody and herbaceous, can be planted successfully in Metro Vancouver between the months of September and June as long as the soil isn’t frozen or saturated. For larger woody plants, it is best not to plant too late in the spring. If large plants are not established before the heat of summer, they will require more water and suffer more from heat stress. Plant larger plants earlier in the spring or better yet, in the fall. This provides a good jump start on plant establishment.
Many perennial plants can also be moved during this period as well. It is best to stop transplanting large perennial material before April so that the emergent foliage is not stressed from the root disruption that happens when transplanting. For larger woody plants, dig a root ball that is big enough to support the plant but small enough to physically handle so that it can actually be moved. Knowing how big to dig requires experience and intuition but there are some guidelines that can be helpful. Dig a circular trench out from the centre of the plant that is 15 cm in radius for every 2.5 cm of stem diameter. For example, if you’re moving a tree that has a stem 5cm thick, you need to dig a trench 30 cm out from the centre of the plant. After a doughnut shaped trench has been dug, chip away at the soil underneath the ball so that the ball is sitting on a narrow pedestal of soil. At some point, the ball can be pushed gently and the last remaining roots will separate. This makes a very satisfying ripping sound. Use a tarp underneath the ball to lift the plant and move it to its new location.
When planting annual plants, including vegetable food crops, it is important to understand the difference between warm-season and cool-season plants. Warm-season plants tend to be grown for their fruits. This group includes tomatoes, cucumbers, squashes and corn. It is usually necessary to wait until the end of May or the beginning of June to plant warm-season plants. Ideally, nighttime low temperatures should not fall below about 12 C and the soil should consistently warm up to 20 C in the day before planting warm-season crops. Soil thermometers are a great tool but you can also use your intuition as well. For example, a well-seasoned gardener will know that it is time to plant warm season crops when they put their hands in the soil and feel that it is warm. It is always a great feeling after a winter of cold and wet soils.
Cool-season crops tend to be plants that are grown for their edible leaves, such as lettuce, spinach, mustard, arugula and kale. These leafy greens can be planted as early as March. Many cool season plants will “bolt” and start flowering when the weather warms up in late spring and summer. This is not desirable for producing greens for eating as the leaves then become small and bitter.
Directly seeding vegetables is not only satisfying and inexpensive, but seed-grown plants produce better root systems and become better established in the garden. Cool-season greens, radishes and peas can be sown in March. In April, carrots, beets, broccoli, bush- and pole-beans, and turnips can be directly sown. It does not matter how many years you have been gardening, watching seeds germinate is always a magical experience.
Forget About Fertilizer
It is a human tendency to believe that everything in this world needs to be managed. The secret to being efficient is to set up the garden so that natural systems can be used to good advantage. That way, the garden mostly takes care of itself. This principle can be employed when considering plant nutrition. When growing plants in soil, it’s better to rely on the natural processes that maintain healthy nutrient-rich soils. Instead of applying synthetic fertilizers, use composts and mulches to replenish nutrients that are lost through harvesting plants. Remove as little material from beds as possible by allowing roots to decompose in the soil and distributing other plant debris with the mulch on the bed surface.
Work Smart, Not Hard
If you aren’t careful, misguided gardening can actually create more work for you later. On one hand, you might be irrigating, cultivating and fertilizing to keep the garden alive, but those same tasks are stimulating weeds and excessive plant growth that needs to be managed. Hard work in the garden is rewarding, but as much as possible, a gardener can save time by embracing harmonious, ecologically balanced systems that create less work in the garden. Rather than constantly fighting the will of nature, a little understanding can go a long way when making gardening decisions. Setting up a garden so that natural systems are working for you is pure gardening joy. Good luck and enjoy the spring!