In the Garden - April 2025
The month of April in Canada means the celebration of Easter and the beginning of spring. Dormant plant buds begin to show signs of life and early spring flowering bulbs push through whatever snow remains. We all begin to feel just that much lighter, brighter and anxious to get outdoors!
Easter Sunday this year in on April 20, 2025. Be sure to visit Floral Acres for all your Easter shopping. Check out the beautiful bright and pastel colors of the season. Floral Acres makes decorating for Easter easy as they carry a wide selection of potted tulips, daffodils, easter cactus, primula and many more spring flowering plant varieties. They also have unique Easter decorations for the home, indoor tropicals and a large selection of seeds for the garden. There is so much to enjoy!
As I mentioned, most plants will be waking up from their long winter’s nap. But how do they know it’s spring? This is a very good question and the answer is fascinating. Like humans, plants have an internal clock that helps them become aware of rising temperatures and longer daylight hours. This awareness is called circadian rhythm. As the temperatures rise and the sun is out for longer, the soil warms and plant hormones trigger plant growth and the cycle begins!
Many deciduous trees and shrubs set their leaf and flower buds before winter. New buds are already in place when older leaves drop in fall. To me, it is one of the miracles of nature that these buds can withstand extremely cold winter weather, only to unfurl in the warmth of spring. Some cold injury can occur when temperatures widely fluctuate in spring or there is an unexpected hard frost. This is one of the reasons that in some years’ fruit trees may not produce a lot of flowers.
Indoors, our tropical plants also sense the longer days which trigger new growth. This is the perfect time to transplant those plants that are root bound and need new soil. New roots feed expanding upper growth which in turn feeds the roots. As indoor plants start to show new growth, increase watering only by a bit weekly and apply a weak houseplant fertilizer. Fertilizer at full strength can begin in early May to mid- August. I like to use an all-purpose water soluble tropical plant fertilizer – half strength in spring and full strength in summer until August 15.
If we still have some snow covering the ground in early April, stay off the lawn and perennial beds while they are frozen, or very wet. Walking on this frozen or wet lawn will damage the grass, compacting the soil and grass roots below. Let the soil dry before applying compost around your perennials in spring. Keep an eye on the weather for late hard frosts. Have a few frost blankets handy to cover those tender, newly sprouted perennials.
Let older lawns dry out considerably before raking, dethatching and aerating. After aerating is the time to top-dress a tired lawn. When top-dressing I would take the time to mix the compost, a bit of new grass seed, and slow-release lawn fertilizer together in a wheel barrow, then apply it over the lawn to a depth of 1.25 cm. Then lightly water. Keep the lawn moist until the new seed sprouts.
The first spring watering of an existing lawn should be a deep watering. This forces the grass roots to penetrate deeper into the soil, avoiding the stress of being shallow rooted.
Mow your lawn two times before applying a granular high nitrogen fertilizer. Make sure you water the lawn about two days before fertilizing and that it is dry before you feed. Sharpen the mower blade and set it at a height of 8 cm. Leave clippings on the lawn as they will break down and add nutrients to the soil. For organic weed control, apply corn gluten meal to the lawn which inhibits weed seed germination. Do not apply the corn gluten if you have just over-seeded the lawn with grass seed.
The beginning of April is also a good time to prune your summer flowering shrubs and trees. Take off anything that is obviously dead, diseased or broken. In early spring you can prune back Hydrangea arborscens and paniculata, Spirea japonica (summer blooming varieties), Potentilla, Yellow and Purple Leaf Elders, Tartarian Dogwood ( Cornus alba cultivars) and Alpine Currant. Shrub roses can be given a light pruning to shape and remove dead, diseased and damaged wood.
Like everything else in life, there are some exceptions to the rule! You should not prune maples, birch or elms. Maples and birches will weep heavily from the cuts once the sap flows and there is an elm pruning ban in Saskatoon (and all of Saskatchewan) from April 1 to August 31.
Do Not prune forsythia, lilacs, mock oranges, double flowering plum or any other early flowering shrubs. The time to prune these shrubs is after they bloom.
Pruning can also benefit shrubs and trees that suffer from the fungal disease called Black Knot. This fungus attacks shrubs and trees in the Prunus family – this includes Maydays, Schubert Chokecherry, Native Chokecherry, Saskatoons, Amur Maple, Nanking Cherry and many more. Unfortunately there is no cure for Black Knot. In April before leaf break you can still see the distinctive thick, black ‘knots’ clear enough to identify and prune them out. Do wear gloves and sterilize your pruners between every cut. Cut 15-20 cm below the knots. Do not leave branch stubs. Diseased branches should not go in the compost. Clean and sterilize your tools after pruning.
At the end of March or beginning of April is also the time to spray fruit trees with dormant oil and lime sulphur. They are often sold together as a kit. Dormant oil suffocates overwintering insect pests and their eggs. The lime sulphur serves as a miticide and fungicide. Apply when outdoor temps are consistently above 4 degrees C and the trees are still dormant. Trees and shrubs that should not be sprayed with dormant oil are blue needled Junipers, Norway spruce, Dwarf Alberta Spruce, Eastern White Pine,
Douglas Fir, Cedars, Yew and blue and green Colorado Spruce. The treatment takes the blue off the existing needles but any new growth will be blue.
Seed potato varieties will no doubt be out in garden centres in early April. You can buy seed potatoes ahead of planting time but keep them cool and in the dark. Planting should occur when the garden soil becomes workable and at least 7 degrees C. Remember you can also grow potatoes in large cloth grow bags.
Depending on the weather, the Adult Red Lily Beetle may emerge in mid- April and begin to feed on newly emerging perennial lilies. They are easy to spot as they are a distinctive red color and are best picked off the new shoots by hand. Their bright red eggs are laid in a straight line on the underside of the leaves. Remember to look for the adults under the new leaves – they do like to hide!
Another pest to watch out for in early spring is the larvae of the Golden plusia moneta (moth). Their larvae feed on new delphinium shoots creating a shredded appearance. You can interrupt the larvae’s life cycle by removing the delphinium’s growing tips and send these pests to the garbage. The delphinium will quickly send out more shoots and grow on.