The tarps and burlap have come off of our tender apple trees, the snow is gone and the ground is drying up. Now we just have to wait for the magic to happen and the fruit to grow, right? Well maybe. Unfortunately, we don’t always get off that easily up here. Yukon fruit growers have work to do in all seasons to ensure a successful harvest come fall. In the spring this involves two main strategies: avoid early bloom and watch that weather.
While we all know we don’t have any guaranteed frost-free months in the Yukon, the likelihood of a freeze definitely goes down as spring comes on. When this reaches the growing threshold depends on your exact location and microclimate, so it is a good idea to get familiar with the nuances of temperature in your own yard.
To avoid too many sleepless nights, we can encourage plants to remain dormant longer. This may seem counterintuitive when we have such a short season, but there is a balance to be struck. For apple trees, we find the ideal time for them to “wake up” is just after the background vegetation begins to green up, taking cues, for example, from aspen or willows.
If your trees are sheltered for the winter (as we recommend), opening up their enclosures in late March or early April after the threat of -40°C has passed is a good way to keep them in sync with the season.
Remove the covers when the snow is clear and hope for good weather thereafter. Using solid, light-coloured tarps to shelter trees keeps them shaded and cool. Transparent materials allow heat to build up in a greenhouse effect, encouraging your trees to come out early when risk of freezing remains.
If your trees are in a permanent cold frame or greenhouse, you can decide if you want to vent and/or shade the shelter to maintain a cooler temperature or promote the trees to come out early – in which case you will need to monitor and apply heat if necessary during the early spring. For later maturing varieties this is the best path forward.
Once the blooms are developing, the second tactic comes into play: weather watch. Flower buds on many trees and shrubs form the previous summer, and once they begin to swell the following season the plant enters a more vulnerable stage. Active growing tissues and open blooms can suffer damage from a -3°C frost, so once flower buds are the size of a pea, watch the forecasts and be ready with row cover, bed sheets or tarps to cover up your trees to help them through a particularly cold night.
Woody growth – and even flower buds – can handle cold down to -40°C if tissue is completely dormant mid winter, but much less when growing.
Thermometers with remote alarms are available if you are the anxious type, and I am told these are also easy to rig up with DIY technology… it’s Greek to me, and I’d love to hear about it if you have success with this!
A couple further tips to ensure a healthy transition to the growing season are to ensure your trees are well-watered early, and to complete pruning before buds swell and fertilize as soon as the ground thaws so nutrients are available early.
May all your endeavours be fruitful!
Pollination troubleshooting
“My apple tree blooms but it won’t fruit…”
- Apple blossoms require pollen from an unrelated apple tree to fruit (this includes flowering crabapples!)
- The maximum suggested distance between trees for good pollination is 30m.
- Planting early-blooming plants like haskaps that are attractive to bees and other insects is way to bring in pollinators.
- If the weather is wet, windy or very cold and the insects aren’t flying, hand-pollination with a paintbrush is a way to hedge your bets for a good crop.
- Only have one tree? With permission of course, bring home a few blooms from a neighbours tree and do the deed yourself.
