Spring Cleanup in the Garden
Updated: Jan 8, 2021
We all want to give our plants the best start possible each year. When we have a good, organized plan for cleaning up the garden in spring we make our summer and fall gardening tasks faster and easier. Let's not forget that it also will keep our plants healthier.
Trees and Shrubs
Very early spring is a great time to prune most trees and shrubs. By very early, I mean on the line between late winter and early spring (around early April here in Calgary). Preferably, there should not yet be any buds breaking out on the branches. We want to get any pruning done before the sap starts to really flow. Start off by removing any dead, damaged or diseased branches. After that is done, you can begin pruning for shape or thinning. Click here (link coming soon) for details on how to prune correctly and why you might want to prune at alternate times of the year. There are a couple of exceptions that should not be pruned in very early spring:
Early spring blooming shrubs should be pruned after they are finished blooming to prevent removal of flower buds formed last summer. These include: Lilacs, some Mock orange, American highbush cranberry, Forsythia, Flowering plum and some of the Spirea.
High sap trees should not be pruned until full leaf development is complete. Pruning early will result in excessive sap loss and reduced health of the tree. These include all of the maples.
Pruning can be a dangerous job that may require an expert. If you have a very large tree, a limb which may cause property damage when it is removed or have questions about diseases or insects, please call in the professionals. Arborists are there to help for big jobs or if you are ever unsure. Be safe!
Water if needed
Once the ground starts to thaw, our gardening work really begins. Check to see if your beds need water, especially the ones under your house eaves. Calgary has a particularly dry winter and our plants need moisture to break dormancy. Now is also the time to take off any protective wrappings or screens around our evergreens and give them a good water as well.
Amend and clean up beds
Every plant label I have ever read says to fertilize with an all-purpose fertilizer in early spring, but I am not a big fan of chemical fertilizers. There is something much better for your garden: good compost! Why is compost so amazing? Check out the section on compost in the article A Practical Guide to Raised Beds. 1-2 inches every year will make a world of difference in your gardens. If you didn't add this compost in the fall, now is the time to do it. No need to mix it in, just spread it around on top of your soil. If you have mulch on your beds, just rake it to one side, add the compost and rake the mulch back over it. This also helps to freshen up the look of your mulch. Re-edge your beds if needed.
When can I plant trees and shrubs?
The quick answer is whenever the ground is thawed enough to dig a hole of the necessary size. Remember, that will be a decent sized hole for a potted tree or shrub. The ground should be thawed all the way down to the bottom of your hole. Don't forget to harden off your plants if they have been nursery grown or have been in the garden center for a significant amount of time. They may not be use to outside temperatures, wind or precipitation yet. Ask staff where you purchased your plants if you are unsure. Trees and shrubs can be hardened off the same way you do for transplants. See the article on Transitioning Transplants to the Garden.
Cleaning up your plants
As the snow starts to melt, begin watching your native trees. When their buds swell, it is time to look for growth on your perennial plants. As you see each of those sprouts starting to poke up from the ground, begin gently pulling back the protective mulch around the stems. This will help the soil warm up faster and make it a little bit easier for those shoots to start growing. If we get a frost within a few days of pulling back that mulch, cover with sheets for a bit of added protection. Don't freak out if you miss covering them up. Even if the newly emerged sprouts get frost bitten, the crowns and roots will survive and live to sprout another day.
Spring is also the best time to cut back the dead leaves and stems left behind from the previous year. I am a strong proponent of cutting back perennials in the spring instead of the fall for a few big reasons:
dead leaves and stems of perennial plants act as insulation on top of the root zone throughout the winter
that dead material helps trap snow, leaves and other debris, which in turn act as additional insulation
that additional accumulation of snow helps add moisture directly to our plants roots where it is needed most
beneficial insects, such as ladybugs, overwinter in that dead plant material and will reside there until it is warm enough for them to emerge in the spring. We need as many good guys helping out in the garden as we can get!
Here in Calgary, we need as much insulation for our perennials as we can get. Because of our chinooks, we often don't have the snow cover that many other places enjoy (one time I am jealous of our Edmonton neighbours). Snow can keep the temperature of the soil around our perennial roots warmer, sometimes up to 12 C warmer depending on snow depth. That can make a big difference in whether our plant makes it through the winter or not. The more insulation the better!
When those shoots start to make their appearance, cut the dead material back to about 2 inches, or just above the new growth. Be careful not to give your new sprouts a trim at the same time! To trim tall grasses, like Karl Forster Feather Reed Grass, just grab the old dead growth in one hand (just like a ponytail in your hair) and cut below where you have grabbed but above the new growth. Quick and easy! Clear out any dead leaves and other debris that are packed in there. I like to give the sprouts a gentle brush with my pruners to break off any really old stems that are loose and ready to be removed (see photos below). Your perennial plants are now free and clear to spring forth! Pun intended. Leave your evergreen plants (such as Dianthus, Bergenia, and many of the ground covers) alone. They don't require cutting back at all. Just remove any brown dead leaves you find.
Most importantly, don't give up on a plant if you don't see new growth right away! I always tell people not to get really worried until at least June 1st. Then, if you still see no growth, dig around the base of the plant with your fingers and look for white nodes on the roots. If they are there, your plant is alive and just taking its time. Some plants are just naturally later to come up than others. Asclepsis (butterfly weed), Platycodon (balloon flower), Chelone (Turtlehead) and Hostas are prime examples. We need extra patience with those.
When can I plant perennials?
If our existing perennials are popping out of the ground, you would think it would be fine to plant new ones, right? Yes and no. If you have a perennial you just dug up out of a neighbours yard, go ahead and plant it. If the ground was thawed enough to dig it up, it is fine to plant. However, if you have a plant that you purchased from the garden center or nursery, you may want to wait a bit before you put it in the ground. The majority of the perennials we purchase in early spring were raised indoors in a greenhouse or have spent minimal time outdoors in balmy British Columbia. That means they have not experienced the wind, insects and cool nights of our spring Calgary climate. They should be hardened off just as you would any other plant that has lived its life indoors until now. See the article on Transitioning Transplants to the Garden for details on hardening off plants. Our last frost date (around May 23rd) or later is generally a good time for planting perennials. But remember that our weather can be fickle here in Calgary, cover any newly planted ones if a frost warning is issued.
Early spring is also the perfect time to divide our plants. Many perennials, as they get older, need to be dug up, pulled apart into 2 or 3 healthy pieces and replanted every few years. This helps rejuvenate older plants. If your perennial looks like it is starting to die out in the center, but is perfectly healthy around the outside, it is time to divide it. Early spring, when the plant is starting to sprout is the best time to do this. The plant has not grown too large and unwieldy to manage and it is just getting ready to put on a burst of growth. Keep in mind that not all plants should be divided, such as those with a taproot.
Annuals, Vegetables and Bulbs
When to direct seed and transplant
There are a number of veggies and annuals, that are cool season plants and can be sown directly into the garden long before our Last Frost Date (LFD). There are also many of them that are native to Mediterranean climates and need to wait until a few weeks after our LFD. I put together an infographic for the Calgary area with approximate dates for when seeds (vegetable, flower and bulb) as well as transplants/bedding plants/starter plants (vegetable and flower) can get planted out.
I repeat, these dates are approximate! Each and every year is different, especially here in Calgary. Snow on May long weekend anyone? Temperatures will be more accurate than dates as an indication of when to plant, so check the weather report daily. A few things to note:
"Soil can be worked" when it is no longer frozen (to the depth you need for planting) and when it is no longer sloppy wet.
Cool season crops can take some frost but not hard frost, where the ground is frozen solid 2-4" deep.
"After any chance of frost" is actually after our Last Frost Date because this date is an average over a number of years, not necessarily the last time we will get frost this year.
"Warmer night time temperatures" are a consistent +10 degrees Celsius.
Don't forget to harden off any plants that are not use to being outside.
If you see a frost warning in the forecast and you have plants that are not frost tolerant already planted out, an old bed sheet or frost protection fabric can be laid over the plants until the frost has passed. Don't forget to take them off in the morning. If we have a heavy, wet snow in the forecast, you will need something sturdier. Wet snow can break plants and branches on trees that have already leafed out. Cardboard boxes, plastic bins and similar items can be placed over plants until the snow is done. If tree branches are getting seriously bent, and you are worried about breakage, go be the crazy looking person with a broom, wacking your trees to get off the snow. Sharing produce later on in the season will help alleviate any rumors about your sanity.
I am not a huge fan of mono-cultured, resource heavy lawns, but I do understand the need for big open play spaces for kids. There are numerous options out there that are far more environmentally friendly, soil enriching and better for our pollinators than good old Kentucky bluegrass. Watch for a future article on lawn alternatives. Okay, I have said my piece. On to caring for your lawn.
Once your grassy areas have thawed and are no longer soggy, you can begin working on that grass. Each spring, give your lawn a good raking with a leaf rake to loosen everything up a bit. No need for power raking! De-thatching is actually quite harmful for lawns, especially in the spring, so don't let the lawn care guys talk you into it.
If your grass is super compacted, now is the time to aerate it. This is not something you need to do every year. Every second year is fine, even for very compact grass. You can hire a professional to do this or diy with a rented aerator, use a handheld lawn aerator or use those cute things you tie onto the bottom of your shoes. Whatever you use, make sure you sterilize your tools/machines before you use them. This is how fairy ring mushroom spores are transferred between yards. Next we add a trio of amendments:
granular gypsum or zeolite, if needed to break up clay in heavy soils
all-purpose grass seed. Look for a mixture that contains perennial rye (which doesn't overwinter, but germinates fast), Fescue (has good deep roots; if you have shade look for a mix with a higher proportion of this) and Kentucky Blue (what most sod rolls are made of)
fine textured compost or good top soil 1/2" deep or 1/3 the height of a blade of grass.
Apply all of these amendments separately to ensure you are applying the proper amounts of each. Follow the directions on the package for details on how to apply and to determine how much you will need for your square footage. A broadcast spreader makes quick work of spreading. Water well! Keep the soil moist at least until the grass seed has germinated.
Corn gluten may be added 3-4 weeks later as an option. Corn gluten inhibits seed germination so it is important to make sure you don't apply it until all of the grass seed has germinated! This is why we wait 3-4 weeks. It is a good option if you have a significant amount of weed seeds that blow into your yard, land on your lawn and go crazy. Spring is when many of these weed seeds germinate and corn gluten can help manage the load. Keep in mind, that it will do nothing for weeds that are already established, only seeds that have not yet started to grow.
You don't really need to ever put fertilizer on your lawn, compost is much better. I have raved on about compost numerous times now and for good reason! But if you are insistent about fertilizer, it may be applied once your lawn is growing well. Remember to follow the directions on the package. Over fertilization results in dead grass, harmful runoff into lakes and streams, potential poisoning of adjacent plants and money wasted for you too. Or just top dress with compost like I mentioned above.
That is it for spring clean up! I know it sounds like an intimidatingly long list, but just take your time and get through it slowly. Don't for get to pause every once in a while and appreciate the sunshine and green smells that we missed so much in the cold months of winter. And don't forget the sunscreen :)
Yummy gardening everyone!
Eldorado Weather (https://eldoradoweather.com/canada/climate2/Calgary.html) for in depth Calgary climate information.
Lee Valley Tools (https://www.leevalley.com/en-ca) for aerators, spreaders and other tools.
Stacey Murphy (https://www.youtube.com/channel/UCK8WWphD0zYS4c5jsLOOOmg) for lots of videos on everything to do with growing food.
https://www.veseys.com/ca/canada-hardiness-zones-frost-dates for last frost dates for your specific locale.