When bulbs get pushy, divide them and their perennial cover

Fall is time to reap gold from daff’s growth

 

Several daffodils multiplied and choked out my coreopsis between the sidewalk and house. Should I dig up now and replant only one daffodil bulb, and then try dividing/replanting the remaining coreopsis ('Mercury Rising') clump? - D.D. -

The threadleaf coreopsis variety 'Mercury Rising' is one of our favorite new perennials. (Okay, so it’s been around for a decade. We lose track!) We feel for your poor baby, squeezed between concrete foundation, pavement and muscular daffodils. Easy to see how the coreopsis would run out of room to grow.

‘Mercury Rising’ coreopsis blooms all summer if it’s young. It does a good job of self-rejuvenating – see the husky new shoots developing at the base? (New shoots are pink. There is also a whole new runner, white #3)

‘Mercury Rising’ coreopsis blooms all summer if it’s young. It does a good job of self-rejuvenating – see the husky new shoots developing at the base? (New shoots are pink. There is also a whole new runner, white #3)

This plant is just one year old, grown from a tiny division made last fall. Being young allows it to have so many flowers for so long. It’s been in bloom 3 months without any deadheading.

This plant is just one year old, grown from a tiny division made last fall. Being young allows it to have so many flowers for so long. It’s been in bloom 3 months without any deadheading.

If a threadleaf coreopsis’ new shoots have nowhere to grow because bulbs beneath are filling and competing for every drop of water and iota of nitrogen, the coreopsis will decline. So step in and divide underlying bulbs to keep the fight fair.

 Yes, start digging!

Yes, we would dig up the whole shebang, now, divide to individual daff bulbs and return no more than three good sized single daff bulbs to that spot. Plant them deep, 12" down. Deep, they will spend more of their "dormant" time each year beefing up one bulb and less time making daughter bulbs.

We dug a clump of daffs in September one year. Here is just one division of the 15 we made from that clump. All of those roots have grown in just a few weeks since the soil began to cool. It’s a heck of a lot of competition for other plants in the bed.

We dug a clump of daffs in September one year. Here is just one division of the 15 we made from that clump. All of those roots have grown in just a few weeks since the soil began to cool. It’s a heck of a lot of competition for other plants in the bed.

Compost, please

As you backfill the bulb planting hole or holes, add compost in a volume equal to the bulb- and coreopsis debris you removed. It may look like this makes the bed high. It doesn't. The renewed soil will settle and when it does the growing will be better if it is not depressed from loss of organic matter.

The extra bulbs can go wherever you please but do not replant them in this space.

Salvage every piece of coreopsis you can, choosing new, supple rhizomes over drier, woodier bits. Space the pieces to cover however much space you want the coreopsis to cover next year. It will!

 

This 5’ x 5’ coreopsis bed was planted from one 3 year old plant of 'Mercury Rising' split into 25 pieces last fall. The vigorous young plants began blooming in July and are still going strong here in October.

This 5’ x 5’ coreopsis bed was planted from one 3 year old plant of 'Mercury Rising' split into 25 pieces last fall. The vigorous young plants began blooming in July and are still going strong here in October.

Rotation’s always a good move

You can also rotate crops, try something different in combination with your daffodils. Geranium 'Rozanne' is also long blooming, but larger. Golden feverfew (Tanacetum parthenium 'Aureum') has great foliage and will bloom all summer if you keep it deadheaded. Or you might try something that has attractive foliage in summer before it blooms in fall, such as Sedum cauticola.