It’s always the edges- this is where the weeds seem the worst and the most annoying! A weed growing among my dahlias doesn’t bother me as much as the ones that grow along the edges. So last year I decided to do something about it.

Now you can always just put down some mulch- chips or straw or even run a bit of landscape fabric closer to your plants. But I saw a greater opportunity here! I began to side plant my dahlia rows. Now that we are perennializing some of our varieties, I figured it wouldn’t be a big deal if we had plants running down the sides.

So here’s what I’ve tried so far- the good, the bad, the ugly (well none of it’s ugly but some just didn’t work!)

Let’s start with what I wouldn’t do again: Spreading herbs- Oregano!

Purple Flowering Oregano side planted alongside some Marionberry Milkshake Dahlias

Flowering oreganos are a great plant to have in your garden and I highly recommend them- just don’t side plant them alongside your dahlias b/c they are more vigorous than the dahlias! The oregano was planted last spring and the dahlias about 1.5 months ago. Once the dahlias get bigger, they’ll compete better but this picture was taken after we whacked the oregano back b/c it was encroaching on the plants and starting to swamp them. I’ll give this oregano one more year after this one b/c those dahlias will be on second year growth— therefore faster and bigger plants. But I wouldn’t do this combo again and don’t recommend it.

I also tried nepeta last year- Walker’s Low to be exact. Great plant— just don’t put it near your dahlias. It spreads and also flops over the dahlias when they are small. But the worst part: it attracts spider mites!! I had one of the worst infestations I’ve ever seen on the dahlias in that row. So we dug all the nepeta out this winter and moved it far away!!

Ok— So what’s working so far! Sedum- I have 5 beds that are side planted with sedums. This is the second year and the plants are getting bigger but I feel like we are still good space wise. Sedums spread a little but not aggressively. They also hold themselves up well without additional support— I think this is important.

Autumn Fire Sedum side planted along Peaches N Cream Dahlias

I do think the variety of dahlia plays a role too— I tried to match my side plant to the size of my dahlia. I don’t think I’d try this with Cafes- those plants are monsters. But Peaches N Cream is not a massive dahlia so this works well.

This is geum planted along side annual scabiosa right now but that will be switched out for dahlias once it flowers. Geum is an easily grown from seed perennial. Flowers in April/May- I also think flowering time is important. I prefer things that flower before the dahlias I think I’ve decided. (Sedums excepted). These plants will spread a little but shouldn’t get too unruly and I think will actually appreciate the little bit of shade from the dahlia foliage during the hot summer. I have to admit- I think geum plants are really beautiful- they have a gorgeous leaf shape!

I’ve got two beds with yarrow along the edges. Currently we have the remains of our late ranunculus crop in there but they’ll be switched out soon for dahlias. I really think this combo is going to work well. I’ve been observing the growth rate of the overwintered dahlias and they should grow fast enough to support the yarrow. The yarrow should flower and then be followed very closely by the dahlias. The yarrow forms a nice mat of green foliage during the winter to keep weeds down. I have a feeling this might be one of the best combos yet.

I’ve got some salvia coming to try on another row this year. What are your thoughts? Have you ever side planted anything to keep down weeds? I’d love to hear of any perennials you think would work well!

Mulch Alternatives- for beauty and the bees!

Early Season Pest Control