Saturday, May 2, 2015

Dahlia Do's and Don'ts

Flowers, like celebrities, can have cyclical popularity. Based on the volume of customer questions, dahlias are the smokin' hot plant right now. Never grown them? Check them out at your local garden center and prepare to be dazzled.  

A wealth of choices
Hybridizers have expanded the range of flower and plant sizes, colors and flower forms so there's a dahlia for every taste. It's pretty darned cool to watch a quarter-sized bud open into an 8" (or larger) flower later in the summer! Yep, I'm in awe of big ole' dinnerplate dahlias.

Here are a few tips for success from my experience growing dahlias over the years as well as from people who grow them by the hundreds.

Undivided dahlia clump
The smaller bedding dahlias can be grown from seed, but the large-flowered varieties are grown from tubers (potato-like storage organs). They're most often sold as undivided clumps with multiple tubers. Don't just dig a hole and plop the old clump back in the ground. Get a sharp knife and cut a tuber from the mother clump. Each tuber must have an eye, or bud, to produce a new plant. Eyes will be at the end of the neck of the tuber, coming from last year's stem. A dahlia clump might have as few as one, or as many as 3-4 eyes.

Divided tuber with eyes
Like tomatoes, nothing is gained by planting dahlias too early. They're tropical in origin and shouldn't be planted until soil temperatures are consistently above 60 degrees F. They abhor cold, wet soils.
  1. Dig a hole 4-6" deep. The tuber will be placed horizontally in the bottom of the hole. Life is easier when you place the stake (you'll need a stake for these big, vigorous plants) in the hole next to the eye of the tuber. Dahlias, like vampires, resent having a stake driven through their heart, which is the tuber!
  2. Some growers recommend mixing dehydrated manure into the backfill soil as the organic amendment. You get the bonus of a small amount of nitrogen, phosphorous and potassium.
  3. Important: Dahlia wisdom is our spring soils generally contain enough moisture that you don't water at the time of planting. In fact, don't water until you see the first shoots breaking through the soil.
  4. Dahlias are an exception when it comes to mulching. You actually want the sun to hit the cool/cold soil and warm it up. So, don't be in a hurry to mulch. Remember they respond to sun and warmth.
  5. If you want a shorter, bushier plant (not a bad idea with plants that may be 6' tall by summer's end) you can pinch out the tip. As soon as the plants have more than 3 pairs of leaves, reach in gently with your fingers or a cutting tool and remove the growing point, leaving 3 pairs of leaves intact. Like most pruning this will produce a shorter plant with more shoots and potential flowering stems!
  6. Big flowers equal hungry plants, right? That sure seems like it would compute. But many dahlia growers urge against lots of nitrogen. Use a granular fertilizer with a ratio of twice as much phosphorous as nitrogen. Example: 5-10-10 (nitrogen, phosphorous and potassium). Apply a month after planting, then a month later. Avoid water soluble fertilizers.
  7. When we get into hot weather water deeply when needed. Remember you planted those tubers 4-6" deep. They have lots of thirsty leaves and flowers later in the summer when it gets hot. Don't use wilting as your indicator that it's time to water. Always water deeply before wilting occurs.
  8. As your dahlias start budding you have a fun decision to make. Do you want masses of smaller flowers, but lots of color to be viewed from a distance? Or, do you want big, honking flowers for cutting or bragging rights (It's a guy thing, like having the first tomato on the block)? The former, do nothing. The latter, remove the buds paired on either side of the larger central bud as soon as you can handle them. The plant's energy will be directed into that remaining bud and will really increase the flower size.
Dahlias - definitely not for the fairy garden!!!             

Cactus-flowered dahlia


Tuesday, March 24, 2015

Timely Tips for Spring Garden Cleanup

Are you itching to get out and start playing in your garden? Me too. It's time to: prune, mulch, stake and most important - plant! Here are a few things to consider as you head out in Slogger-shod feet and West County Rose gloved-hands armed with Felco pruners.

Snow Mold
1. Lawns - Check turf for this winter's gift - snow mold! You can't miss it (see picture). Symptoms look worse than their long term effect. Snow mold will disappear with fertilization and light raking once the ground warms and dries a bit more. Don't rake in deep shade where shallow-rooted fescues reside. You may pull them up and out. Fungicides are unnecessary.

Vole Tunnels
2. Voles - Yes, that's a "V", not an "M". This picture was taken in mid-March as the snow receded. My lawn has never had vole damage before, although I've railed about their potential winter damage on trees and shrubs for years. It looks as though I'll be raking, tamping lightly and reseeding areas of my back yard as soon as the soil thaws more.

Northwind Switchgrass
3. Perennial cleanup - For those gardeners that didn't get out the scythe (just kidding, I use pruners, too, I do) last fall the time has come. Try to begin cutting back before the days get too warm and new growth starts emerging in last year's stem residue. You may need to remove winter tattered foliage ("deadleafing") rather than doing a to-the-ground cut back on some evergreen perennials like Bergenia, Heuchera and Hellebores, for example. Don't cut back creeping Phlox, Oriental poppy and Iberis, or you'll be out of luck.

4. Perennial support - Don't forget last year's promise to yourself to get the cages, hoops and "grow through" plant supports on early. Remember trying to wrestle those 3' tall peonies into their cages? Gardening is much more fun when we're proactive with this very necessary task. This may even apply to shrubs. Let's get those 'Annabelle' Hydrangeas contained early so their beautiful ivory heads aren't resting on the ground this year.

5. Slug prevention - You know which of your prized perennials are attacked by slugs every year. At spring cleanup simply apply earth-friendly Sluggo (it's iron phosphate) around the crowns of susceptible Hosta, Ligularia and other slug-victims. They ingest it, stop feeding, and pass on to Hosta heaven before they reproduce. If applied preventatively it's really easy to have beautiful unblemished perennials.

Spring Break Tulip
6. Spring bulbs - Deer and rabbits  won't touch daffodils. Tulips are a three course meal. Foliage, buds, flowers- all fair game. While you can erect physical barriers that sort of negates the idea of a beautiful color display to welcome spring. However, there are a number of great repellents that can be applied so your garden can look like a slice of Holland. Both Bonide's Repels-All and Plantskyyd repellents come in granules to apply to soil, or liquid to spray directly on plant parts. They work! Don't forget to fertilize your bulbs this spring, either as they emerge or as they finish flowering.

7. Roses - Don't be tempted to remove winter protection too early. Don't be afraid to prune roses (other than climbers, species roses, and some shrub roses) hard. Even if my roses have green canes 15" or more I cut them back to an outward facing bud, leaving the stems (canes) only 4-8" tall. What rosarians say about pruning hard and getting more new basal branches is true. You'll also be removing overwintering black spot spores that lurk in old leaves and canes.

8. Soil preparation - Plant performance is all about soil, soil, soil. Spring cleanup and planting is the perfect opportunity to enhance your soil, especially if your garden has dense clay. Take this time to topdress annual, veggie and perennial beds with compost, leaf mulch or dehydrated manure. This can be cultivated in, or in the case of new beds rototilled or spaded in. After a couple of years of this TLC soils will start showing big structural improvements- and your plants will respond accordingly.

9. Weed prevention - Many weeds (especially annuals, the ones that grow for only one season) can be thwarted with pre-emergent weed control. After you've done whatever raking or cleaning you're going to do in beds (especially those with bare soil) apply the granules. Water in or lightly cultivate the granules into the soil surface. Understand that you're preventing weeds, not killing those that have germinated and are growing. Read directions carefully and fully BEFORE application to get maximum results!

10. Mulch- The tests have been done, the results universally show that virtually all plants perform with better, more vigorous growth if they're mulched. Spring is the time to get that organic matter down (leaf mulch, cotton burr compost, shredded pine or hardwood bark, etc). Remember you're mulching roots, not stems. So, try and leave mulch-free zones immediately adjacent to annual and perennial stems, and "trunks" of trees and shrubs. While mulch will dramatically deter weed growth you can apply pre-emergent weed control to the surface of mulches, if you like.

Emerging Tete-a-Tete Daffodils

Let the planting, mulching, pruning and staking begin!                                                                   

Tuesday, December 23, 2014

Off to the Amaryllis Races

It's really easy to understand why amaryllis are so wildly popular. They grow quickly once awakened from dormancy, have flowers that are the epitome of spectacular, are practically maintenance-free (can be grown in water or soil) and are just plain fun to watch! I heard people are even having amaryllis races - they all pot them the same day, then keep track of whose grows fastest, tallest, or has the most flowers. But they're so-oo-o-o easy even a tot could grow them.

Big bulbs!
My first memory of amaryllis was shopping with Mom at the florist for an azalea. I saw a box on the counter full of the biggest bulbs I had ever seen. The picture promised an amazing plant full of huge red trumpet-like flowers. I was hooked and coughed up $ 5.15 of my own money. I was so taken by the idea of this big, not-so-pretty bulb throwing up a flower spike like the picture that I would have paid double that. Remember, this was 1959 and that was weeks (plural) of allowance.

I potted the bulb upon arriving home and a few weeks later bada-boom, bada-bing, the payoff came as promised. It grew jack-in-the-beanstalk fast producing not one, but two spikes of dinner plate dahlia-sized flowers that blew me away. Too cool. I felt up to any horticultural challenge after that.

The hybridizers are having fun!
In the ensuing decades hybridizers have been busybusybusy with amazing results. The color range has been dramatically increased. Varieties now have contrasting star-burst patterns in the center. There are also doubles that resemble florists' roses, as well as dwarf cultivars with more delicate flowers.

There are plenty of articles on growing them successfully, so I'd like to share a few tidbits you may not find elsewhere.

1) They may or may not bloom for Christmas. If they've been grown in the southern hemisphere they'll have fulfilled their full dormant period and should be ready to start growing as soon as you pot them. If they've been grown in the northern hemisphere they may need more "rest" before the show begins - so be patient. They'll brighten winter days in January and February just as well.

2) Water thoroughly when you first pot them. Don't water again until you see buds or leaves emerging from the neck of the bulb. That may be weeks if the bulb is still dormant. That's okay. If the bulb isn't ready to grow, don't force it by watering. That may lead to a rotten bulb. It'll grow when it's good and ready.

3) If you're trying to save the bulb to rebloom for next year, feed heavily throughout the spring and summer. It takes a lot of stored energy to produce those enormous blooms. I read once that for every four leaves the plant produces you should expect one flower spike the following season.

4) I'm loathe to mention this as is seems horticulturally perverse, but for those that have suffered tall amaryllis, they can be given a 4-6% alcohol solution (absolutely no more). This will stunt them and keep them more compact. Flowers will be full size, but the stems will be shorter. You'll need to Google that formula. I won't dispense moonshine concoctions for innocent amaryllis.

If I was a parent or grandparent with young children trying to interest them in the natural world an amaryllis race seems a perfectly fun place to start. Gentlemen, ladies, start your plants.

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