July is when I realized that I was insane. Or at least that my decision to keep up with the weeds in the rose bed without mulching must have been made in a moment of insanity. My father told me that roses did better with bare soil but now I remember that he said that when he was fully retired and could tend to his roses (and the weeds) every day.
To mulch or not to mulch is a serious question. Here in the North, mulch has a number of negatives, especially the typical bark or wood chips that are so widely used. These mulches can:
- Raise the acidity levels, and most New England soils tend to be a bit too acidic already.
- Tie up nutrients as they decompose, at least right where they touch the soil.
- Keep soil cool, and I’m always running around in the spring with a soil thermometer, willing the soil to heat up! Heat up!
- Prevent repeated applications of composts, manure and other soil amendments, throughout the season.
- Bring their own fungal diseases or weed seeds.
- Create considerable expense.
So why mulch, I asked? And with that long list, you might also. Well, here’s my story from this summer, with the plants I raise.
- Tomatoes: I don’t have enough space to rotate, and that’s fallen out of favor as people learn more about micro-organisms that live in the soil and have a symbiotic relationshp with specific plants. However, other diseases overwinter in the soil and get transferred to the plants when water splashes them onto the leaves, so mulch can minimize that. See my post on Mainely Mulch. I was very disappointed that it wasn’t free of crop seeds as advertised, but the truth is that even the heirloom varieties that are vulnerable to soil borne diseases are looking good for late July.
- Dahlias: I’m a novice with these. Told not to put them into the ground until the soil warmed, I planted them out in a new bed with soil purchased from a local farmer and thought that the sun warming bare soil would be a good thing. But when I asked some questions about plants that were wilting and failing to thrive, See pictures in Dahlia Problems. I was told that it was probably verticillium or fusarium wilt, the same soil borne problems that tomatos have! Further, because of questions from a gardening freind in Arizona, I learned that dahlias have shallow root systems that don’t like too much heat. Southerners who want to try to grow them should apply a thick layer of mulch to keep the soil cool. It’s all relative, I guess. But I can report that after a thick layer of mulch in July, all of the plants in the dahlia bed, even the healthy ones, perked up and started growing faster. (No, it didn’t save the plants that were already sick.)
- Hydrangeas: This spring, I planted a couple of small “Let’s Dance Moonlight” hydrangeas (picture above) that I’ve been growing in pots into a bed that’s not realy finished. I wanted to continue to reshape the area and add amendments and other plantings before I mulched. The hydrangeas were doing very well except that they would wilt badly in the heat of mid-summer sun. I was wondering if I had to sacrifice their lovely blossoms for this season, to let them develop deeper root systems. But first I thought I’d try mulching them. Since this section of my post is talking about why I do mulch, you know what happened; they thrived.
- Roses: Yes, personally, I’m sad to say that I can’t keep up with the weeds without mulch. Even with mulch, I have to weed. Lots of vining or plants with runners (strawberries, e.g.) don’t need bare soil to settle in. And mulch should never be applied right against the stem of a plant, which creates opportunities for weeds. Especially with roses; they do much better if there is plenty of air circulation around the bud union. That means no mulch but also, no weeds.
So I hope this has offered some advice that you can adapt to your own plantings. I do have a regular feeding schedule of balanced, slow release fertilizers for roses and other mulched plants to compensate for the little bit of nutrients that may be tied up in the decomposition process of the mulch. And I amend the soil in flower beds to lower their acidity every spring and fall. I’m trying to get competent with a soil test kit to make that more accurate. If you understand the needs of your plants and compensate for the down side, mulch can:
- Help with weed control
- Keep soil borne diseases from spreading to new plants
- Moderate soil temperatures