Saturday, September 17, 2016

A Perennial Divided.... Fall or Spring?

Much has been written about dividing perennials. There are many reasons for unceremoniously removing a perennial from the comfort of Earth, separating into smaller plants and replanting. Why do this at all?
  • Increase stock of a favorite variety (for your garden or to give away)
  • Keep plant size in the bounds of its dedicated space in the garden
  • Improve the vigor of an old plant (especially perennials that "die out" in the center)
  • Improve flower quality and quantity with a new, young plant
  • Relocate to a new site
Experienced gardeners often say, "Divide spring-blooming perennials in the fall, and fall-bloomers in spring." There's a certain amount of truth in that. But, like everything we do in the garden there's often a fudge factor if something has to be moved. Here are some garden stalwarts that favor fall division.
Buckeye Belle
Peonies - There's little leeway about the time of year to divide these May stunners. Late summer - early fall is the only safe season to divide a peony. If properly sited in a well-drained, sunny site they're a perennial that just gets bigger and better with each passing year. Frequent division is NOT recommended.

Mid-August through late October is the best peony transplant time in northern Illinois. At this time the pink, red or cream "eyes" (next year's stems) will be fully formed and visible at the base of this year's stems. Cutting to 3-5 eye divisions is a standard recommendation. It will take a year or two to recover from transplant. (9.11.15 Hortiholic post "Prime Time for Peonies" has more detailed info on the planting process).

Chicago Apache
Daylilies are much more forgiving of transplant season than peonies. I personally prefer dividing in September. I read a recommendation in a daylily catalog years ago to transplant when a plant reached 20 fans (a stem of connected leaves) of foliage. That's a hefty daylily. Daylily roots are fleshy and tend to separate fairly easily without lots of mechanical cutting. While you could divide and replant as little as a single fan it's going to be a while before that produces an impressive flower show. I find a 3 fan division produces a good display the next summer.

Princess Victoria Louise
Oriental poppies, when established, make a gorgeous plant with their deep green foliage and splashy crepe paper-like flowers. It's important to know that a month or so after they bloom the leaves start yellowing and the plant disappears, going dormant for weeks in the summer. When a poppy has done its Rip Van Winkle slumber thing it will suddenly (mid-late August) throw up a little rosette of leaves 6" or so tall. These must not be cut off. Those leaves will remain over winter and flower next spring. "Orientals" have a taproot so any type of transplanting or dividing should be kept to a minimum.
Picasso Moon
Bearded iris are probably best separated every four years. They can be lifted and divided as early as 6 weeks after they finish flowering. That is well before fall. The earlier in the summer you do the division the more likely it is that you'll have flowers the next spring. Two cautions: Cut and keep only the newest rhizomes (the creeping rootstock) on the outer edge of the clump, the ones that haven't flowered. Replant those, discard the old, woody ones. Once a rhizome has flowered it will never flower again. Also, make sure the top of the rhizome is replanted slightly above the soil surface. It's a no-no to completely cover bearded iris rhizomes with soil.

Gold Standard
Hostas ... forget the rules. They have. You can lift and separate them spring, summer and fall. I like fall. In mid-late September I cut off the foliage, lift the clump and start dividing. I have an old kitchen knife (long and heavy) that I use to saw through old clumps. Like peonies I leave 3-5 "eyes" per division to give a good show the following year.

Go forth, be fruitful and divide those perennials (but only if they need it)!       

  

    

Thursday, September 1, 2016

Literal Dos & Donts of Fall Lawn Care

  • DO know that August 15 to September 15 is the very best time to do lawn repair in northern Illinois, whether seeding totally bare areas or overseeding thin lawns. Yep, actually better than spring due to less weed competition.
How much sun? This will help
  • DO due diligence and figure out how many hours of sun, partial sun/shade or full shade the area gets. Your ultimate success (or failure) depends upon getting an accurate estimation BEFORE you buy the seed.
  • DO measure the area to be seeded so you know how much seed to buy. Overseeding requires half the rate of totally bare soil.
  • DO assess whether you're going to overseed (recommended if you have 50% or more desirable grass) or kill everything and start from ground zero.
  • DON'T use a broadleaf weed (dandelion, clover, etc.) control to kill weeds before seeding. There's a lengthy restricted time between using these products and being able to safely reseed.
  • DO consider using "Roundup" if you need to knock out everything for a start-from-scratch new lawn. "Roundup" is a nonselective herbicide, absorbed only through green, growing leaves and allows you to reseed almost immediately.
Start with the good stuff
  • DO buy the best seed. It may be a couple of dollars more a lb. but it won't have the inert junk or crap and weed seeds you'll get with "value" seed.
  • DO use Kentucky bluegrass for lawns receiving 5 or more hours of sun a day. Use fescues when you have, say, less than 4 hours of direct sun a day.
  • DO a mixture of KY blues and fescues if you have sun and shade. Don't worry, Darwinism will intervene. In the sunny areas the blues will dominate and in shade fescues will prevail.
  • DO check out having core aeration done if your thatch layer (the spongy layer at the junction of roots and stems) is more than 1/2" deep. 
  • DON'T dethatch. Dethatching is not a sound horticultural practice. Don't do it or have it done. There, I'm climbing off my soapbox.        
  • DO consider slit-seeding if you have a large (bare or partially "grassed") area to renew. Briefly, it's a machine that cuts parallel furrows in to the soil, drops the seed uniformly in those grooves and gives a great result.
  • DO know a slit-seeder is a little like trying to push an elephant around the yard. They're heavy. So, if you're a DIY person they can be rented. Or you can have reputable landscape firms do it for you.
  • DO loosen the soil, preferably to a depth of 3-4". This will promote deep rooting. Harder to do if you're overseeding into an existing lawn. That's when slit-seeders are a smart choice.
  • DO apply the seed at the appropriate rate. Nothing is gained by applying seed too heavily. You should be able to see individual seeds on the soil. They should be close, but not clumped together or on top of each other.
  • DON'T cover with peat moss. Never, ever. If you feel you need to cover the seed a light (and I mean light) dusting of topsoil or fine humus is acceptable.
  • DO use a starter fertilizer. Many lawn fertilizers contain no phosphorous, which is fine for established turf. Starter fertilizers do have phosphorous (the middle number in an analysis, 25-24-4, for example). Seed, or sod too, will really respond to high phosphorous with a heavy root system!
  • DO moisten the seeded soil surface frequently to keep uniformly damp to ensure good germination and establishment. 
  • DON'T flood the seed so that it's floating about.
  • DO the first mowing (with a sharp blade) when the surface is about 3" tall.                 

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