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Perennial FAQs

Find helpful advice on Lupines, Columbines, Peonies, Clematis and more.

Animal Resistant
Clematis
Columbines
Delphiniums
Irises
Lupines

Peonies
Poisonous
Slugs
Transplanting
Virginia Creeper

 

 


 Q.  My lupines are not happy this year. I have had some blooms, but the plants are not healthy- few leaves and many new leaves curl up , bending at the stems. I think there is a mildew problem that I have tried to treat twice-of course it poured rain shortly after. Is there anything else I can do? It is a small bed and I am ready to just cut them all down.

A.  Lupines are susceptible to both aphids and powdery mildew - most often the leaves curl due to aphids, but in severe mildew cases they can curl.  If it is indeed mildew (powdery white leaves) then you can spray the affected plants with a fungicide now, and again in 2 weeks.  Next season, you can spray a preventative application of fungicide around mid/end of June to prevent the mildew.


Q. I have a beautiful columbine that I got from Greenland three years ago.  At least on Sunday afternoon it was beautiful. Last night I went out to do some dead heading and as I worked my way around the garden I got to the columbine.  What columbine?? !!  The leafs were gone, branches stripped bare, with the flowers still looking gorgeous at the top. What happened?

A. Your columbine was more than likely attacked by the columbine leafminer, which will decimate a plant in one day.  It’s a small caterpillar, and by now it’s long gone, looking for other columbine.  The columbine will come back, but in the fall ensure you clean up ALL leaf debris.  Next spring, around early June, spray the plants with a residual insecticide such as a garlic spray, or doktor doom house and garden.  Then, when they go to feed on the plant, they will be taken care of.


Q. I can't seem to get my peonies to bloom. What am I doing wrong?

A.
There may be a couple of reasons as to why your peonies are not blooming. When planting peonies, it is important that the rhizome (the hard 'bulb' the foliage emerges from) is planted no deeper than 2" beneath the soil surface. If the planting depth is fine, check the light your plant is receiving; peonies require a full sun location in order to produce blooms. Thirdly, Botrytis, a fungal disease affecting peonies, can prevent blooming. Symptoms of this include browning foliage, and browning/hardening of flower buds. Should you see these symptoms, plants should be cut back and the soil area drenched with a fungicide.


 Q. I hear conflicting advice on pruning Clematis - when should I prune?

A.
There are several types of Clematis, so several target dates and methods of pruning involved. Here are the specifics for each type:

• Hybrid Clematis (Jackmanii, Nelly Moser) - In many pruning books, Hybrids are divided into pruning categories of B1 and B2. In our cold climate, vines often die back completely to the ground in winter, so these categories are often more a source of confusion than help when it comes to pruning. For all hybrids, wait until growth emerges in spring; if we had a mild winter, growth may come back on old wood, and you can prune any dead wood ABOVE where the new growth begins. If we had a harsh winter, new growth will emerge from the ground; you can then prune back all of the dead wood from last season.
• Species Clematis (viticella) - New growth will emerge from the ground; cut back all of the old wood in spring.
• Golden Clematis (tangutica) - New growth will emerge from old wood; prune only to restrict size, remove damaged branches.

Various other varieties exist (Shrub Clematis, Texas Clematis); for specific pruning information on these, call our perennial staff at (780) 467-7557 or email gardening@greenlandgarden.com


Q. When is the best time to transplant perennials?

A.
As perennials bloom at different periods throughout the summer, each plant will require a different transplant time. Simply put, transplant the perennial when it is least active. For example, Peonies bloom early summer, so are best transplanted in fall, when they are not actively setting buds or blooming. Black Eyed Susan (Rudbeckia) is a fall bloomer, so is best transplanted in spring, when it is not actively setting flower buds or blooming. When transplanting, dig up the entire clump and divide it into 3 pieces. Discard the center portion (this is the original parent plant and is the most exhausted part of the plant). Replant the other two pieces. Always water transplants in with 10-52-10 transplant fertilizer or Later's Root Booster 5-15-5.


Q. My irises have bloomed beautifully for years until this summer....why?

A.
Iris are a vigorous perennial that quickly form a large clumps. These clumps can become quite crowded after 3-4 years, and this can prevent blooms. Every 3 years, dig up the iris clump and divide it. Replant outer portions of clump, ensuring the rhizomes are kept at soil level, no deeper. Discard the center portion (this is the original parent plant and is the most exhausted part of the plant). Water plants in with a transplant fertilizer such as 10-52-10 or Later's Root Booster 5-15-5.


Q. We live on an acreage and are looking for a list of plants that deer and rabbits will not eat.

A. Click here
to see a list of deer resistant perennials. Please note, in years when food supplies are short, Deer will eat just about anything! The most reliably deer-proof plants are those with acrid sap like Euphorbia, strongly scented foliage like lavender and sage, and fuzzy leafed plants such as Lamb's Ear and Lungwort.


Q. We have small children and want to avoid planting any poisonous perennials.

A. Click here
to see a list of poisonous perennials.

For more information, please refer to the following Government of Canada link.


Q. What's the best way to battle slugs in my perennial garden?

A.
Slugs can be a huge source of frustration - they hide in dark moist places during the day, then devour our plants at night. To start to battle slugs, you must first remove their habitat; in spring, replace any moist mulch laden with eggs, keep your garden weed free and trim low lying shrub branches. Removal of slugs is very important - hand picking the slugs in the early morning or at dusk is most effective. However if hand picking isn't your first choice, here are some other suggestions:
• Slug Traps - use purchased traps or plastic containers filled with stale beer - slugs crawl in and drown.
• Safer's Slug and Snail Bait - This quick acting bait has an active ingredient safe for pets and birds but kills slugs when ingested.
• Corry’s slug bait is also very effective, but can be toxic to birds and pets.
• Natural deterrents include crushed egg shells or sawdust spread around and beneath plants.


Q. How can I prevent aphids on my Virginia Creeper?

A. The easiest way to prevent aphids on Virginia Creeper is to spray the plant with Dormant Oil in early spring, when the temperature is above zero but before the buds open up. This will kill any overwintering eggs that are on the stems. Click here for more information.

 


Q. My delphiniums seem to be getting eaten by something and never bloom. What is it and what can I do?

A. The problem on your Delphinium is called Delphinium Worm. Since systemic insecticides have been taken off the market, the only thing that can be done for the Delphinium Worm is cultural control. The worm overwinters in hollow stems and emerges first thing in the spring to attack the new growth on your Delphinium and Monkshood. It feeds on the new growth then migrates to the lower leaves and spins a cocoon. Once it has passed this stage of it's life cycle, it emerges as an adult and these mate. The females lay eggs back on the Delphinium which hatch into young worms. The worms feed for a bit (by this time it is late summer) then migrate to the base of the plant to overwinter in the hollow stems. When the cocoons are first noticed, these can be removed and destroyed. They are light cream in colour. Cut the stems of your Delphinium right to the ground in fall - don't leave any showing at all. This deprives the worm of an overwintering site. When damage is noted first thing in spring, it helps to pick out the worms from the new growth and destroy them. Click here for more information.