Plants are like people. They are affected by hot and cold. They get sick and stressed, just like people. When planting trees, shrubs, and perennials, being knowledgeable about when to plant and starting them off with healthy soil and good watering practices will help them become successfully established in your garden. Trees, shrubs and perennials are long lasting plants and need a good start for a long, healthy life.
You can plant any time of the year, but every season has its pros and cons. Planting in the winter may not be ideal as the soil is cold and the ground may be rock hard. Disturbing the soil at this time can damage it. Summer months are questionable times to plant as drought stresses plants before they can even establish a root system. Spring may be a great time to plant – the weather is warming up and they are actively growing. But because the new growth of roots and shoots takes energy and the plant is not fully established, they could become stressed if temperatures rise or we get a late cold snap. This leaves fall, a season we have not typically thought of as prime planting season. We think otherwise!
Why fall is the best time to plant trees, shrubs and perennials
Cool weather is ideal for gardeners to work in, but also for the plants to grow in. It is almost as if we all say ‘ah’ at the same time after a dry hot spell. Rain moistens the soil and digging becomes easier. When leaves start to drop, we can see the structure of the plant and placement in the landscape is aided by being able to get a better visual angle of the plant. There is more available water for the plants in the fall and soil is still warm enough for root systems to grow and become well-established before spring growth comes along next season. And plant sales pop up everywhere.
How to plant a tree, shrub or perennial
There are different sizes of containers that trees, shrubs and perennials are sold in starting from small 4 inch pots to standard 1 gallon which hold many perennials and some shrubs and 5 gallon sizes and larger reserved for larger shrubs and trees. Some trees are large enough that their root balls are wrapped in burlap.
To remove a smaller plant from a pot, gently turn it upside down in the planting hole and tap the bottom and sides gently until the plant is loosened. Slide the plant out of the pot. For larger plants like trees you can help loosen the root ball’s grip on the pot by pressing in on the sides of the pot while the tree is standing upright. Gently lay the tree on its side and slide the pot off. For ball and burlap, cut off the twine holding the burlap together and fold the burlap away from the root ball. This is generally done while the plant is in the planting hole.
With the plants coming out of the smaller pots you can gently rough up the roots with your fingers or score with a knife to break up any root bound plants. If they are not root bound, it’s not necessary to do this step. Cutting or loosening the roots stimulates them to grow more roots, exactly what you need them to do once planted. For larger containers and especially for woody plants, look for roots that may be encircling the root ball and cut off if needed to prevent girdling, a condition where an encircling root strangles the plant. Burlap does not need to be removed completely, just tuck the burlap you unwrapped into the base of the hole with the root ball. The burlap will eventually decompose in the soil, but will cause crown rot if not pulled back.
Preparing the planting hole
To prepare the hole for planting, dig the hole the same depth and twice the width of the root ball of your plant. If your root ball is 1 foot in diameter, your hole should be 1 foot deep and 2 feet wide. You can take a shovel or ruler and hold it up against the root ball for a measurement of depth and double that for the width of the planting hole. The plant crown should be at ground level when in the hole. The crown will be visible as the place the trunk flares into the wider root ball. Digging deeper will create a loose area under the newly planted root ball and cause the plant to sink into the planting hole over time. Also, when planting too deeply, soil and mulch will fall back into the hole and cover the trunk. In the long run this could cause the plant to rot. The wider width of the planting hole will allow the roots to grow out into the fresh loose soil. As you dig place the soil to the side of the hole on a tarp so you can easily replace it once the root ball is in place. To amend the area with compost make sure you amend the entire bed – amending only the planting hole will create a enriched area the roots will not want to grow out beyond and could also cause girdling roots. Perennials can have compost added to the planting hole as long as they are not woody plants.
Water wise planting
When the rain arrives in the fall, we often forget that new plants need water to become established. Even though the air is misty and the days are cloudy, plants still need water. The misting rain does not generate enough moisture to water a new plant. Be sure to check your plants to see if they need water. Feel the soil at least three inches down around your plants to see if the soil is cool and moist. If it is dry to the touch it is time to water. Rain gauges can be helpful tools so you can measure actual rainfall around your new planting and add water as needed. Installing soaker hoses or drip systems when planting can help too, especially for future watering during the growing season. If you are planting under trees or house eaves remember that plants don’t get rained on in these locations as much as they would out in the open and you may need to check these areas more often. Last but not least, a mulch of compost, wood chips or straw can keep moisture in the soil and keep the plant bed from freezing. Mulch helps keep weeds down too.
Fall Plant Sales
Many nurseries bring new stock in for fall planting season. Here are some places to find a local plant sale near you:
Elizabeth C. Miller Library Garden Tours and Plant Sales: https://depts.washington.edu/hortlib/calendar/tours_sales.php
Northwest Horticultural Society
To learn more about how and when to plant and all about water conservation, please contact the Garden Hotline at (206) 633-0224 or www.gardenhotline.org. You can also find us on Facebook, Twitter, Pinterest and YouTube.