Fall planting of bare-root trees and bushes
It's late fall, the gardens are going dormant, and we have a short window of opportunity to plant bare-rooted trees and bushes for our next season's growth. Why can fall be a great time to plant? We tend to have fall periods with fairly consistent rainfall, whereas our springs have been getting less predictable.
Planting bare-root trees
Generally, we follow the guide to planting bare-root trees that applies to both spring and fall. First, check out this earlier blog post on how and why plant bare-root trees. This applies to both spring and fall planting.
However, it's not all smooth sailing - the freeze-and-thaw cycles we experience in our Maritimes winters mean that our gardens may be susceptible to frost heaving. Frost heaving occurs when temperatures are up, then quickly drop. This causes the water in the soil to expand. Repeating this process over and over may push plants that aren't well established right out of the ground. As a result, roots may dry out, which is detrimental to the plant.
Avoiding frost heaving
There are two factors that are crucial for a successful fall planting - ensuring proper drainage and applying mulch. These are important for a spring planting as well, of course, but we need to pay extra attention in October/November.
Drainage
How do we ensure proper drainage? That depends on your soil and slope! Don't plant fruit trees where water is likely to pool and sit after a storm. With heavier clay soil - gouge the sidewalls of the planting hole, to make it easier for the roots to penetrate the clay. If your soil is very heavy clay – do NOT dig a hole to plant your tree – otherwise, water will pool in your planting hole over time, drowning your tree. Instead of digging a hole, remove the weeds or grass, loosen the soil, create a mound about 1 ft high using good topsoil from elsewhere, and plant the tree in this mound. Water in and compact the soil just as above.
Mulch
Once the tree is planted, top everything up with mulch. Thick mulch, properly applied, will mitigate sharp changes in air temperatures and protect the ground from heaving. Take care to have a 2'' gap or so between the trunk and the mulch, otherwise the rodents will move right in! To apply mulch, place 2-3'' of compost all around the tree. Then add another 6'' of materials, depending on what you have on hand. For example - spread the contents of half to a full bag of leaves, then top up with 2-3' of woodchips, or just add 6'' of woodchips. This blanket of organics will insulate your newly planted baby tree and protect it from frost heaving.
Volunteers showing off their newly planted baby-tree at the Fredericton Botanic Garden food forest. Note the size of the mulch ring around the teeny-tiny plant!
Checking in
Every so often, after a hard freeze, have a look at your new tree. Keep an eye on anything changing from planting time - the angle of the trunk, elevation of the mulch on the planting hole, any shifts. If you suspect a heave, push the tree back in, cover with more soil, and add more mulch. Note the location in the garden - does this area have heavier soil or more moisture than other areas? Compare to other plantings where you're not seeing issues - your garden will be your best teacher!