Mulching tomato plants

Douglas14 · June 22, 2012

Keep in mind I live in central Minnesota. I've heard that mulching tomato plants when they are young will delay their growth, by keeping the soil cool. I'm wondering at what point, if any, mulching won't delay the plant(and ripening of tomatoes). Many of my plants have set at least a few fruits already; many of the beefsteaks are stragglers, that haven't set yet. Most of the plants have really filled out, and are around 2.5 to 3 feet tall.

I've been weeding by hand, and am thinking of using dried grass clippings as mulch, after I weed them. This would prevent further weed growth, and conserve moisture around the plant. I just don't want to delay the ripening of tomatoes and plant growth. The plants already shade the soil some, so maybe mulch wouldn't make much difference in soil temps.?

I'm off to one of my best tomato seasons ever, and I don't want to screw it up. I haven't been a mulcher in the past, so that's why I'm asking now.

kath · June 22, 2012

I don't live in Minnesota, but I've heard the same thing, Douglas, about not mulching until July for the reason you mention. Personally, I ignore it because I don't want soil splash up on the little transplants, so I put a thin layer of shredded leaves and/or grass clippings around them at plant out and keep adding to it so the weeds don't grow through. If your plants are that far along already I wouldn't worry about it now. I don't bother drying the grass clippings but am careful not to allow them to touch leaves or stems of plants. The worms will love it and add their fertilizer for free.

kath

TomNJ · June 22, 2012

Kath's advice is spot on. I set my tomatoes outside in mid May and mulch immediately with at least 6" of hay or straw. The 28 plants in my main bed are now over 4' tall and have over 100 tomatoes set so far. Of course NJ is not MN, so you may plant out later after the soil has warmed a bit.

TomNJ

ScottinAtlanta · June 22, 2012

I mulch when the ground temp hits 70 degrees.

ddsack · June 22, 2012

I rarely mulch in ground - for the reason Douglas stated of retaining soil open to heat from the sun. Growing in the short season north, it's more important to me to have enough heat in any form I can get it, to speed growth and ripening.

I do put a thick layer of grass clippings in my pots, since they heat and dry up much more easily. I also have one garden in a very sandy porous area, and I will mulch the tomatoes in the more vulnerable beds later in July if I am going to be away from home for a week or more, to retain moisture.

Aside from a few short stretches in July and August, we don't have all that much humidity. Normally I spray with daconil maybe three times total during late June through July when the plants are putting on most of their growth. I quit spraying before the greenies get close to full size. I don't have much disease until the cool fall weather takes over and the season is near done anyway. Different parts of the country have different growing conditions - one size does not fit all. In fact Minnesota has at least three zones, and the growers in southern Minnesota might not do what I do.

Douglas14 · June 24, 2012

Thanks for the replies.
I was weeding the tomatoes today, and noticed that the the soil feels cool under the plants without mulch. Either due to shading from the plants, or from the weeds, or both.
I will try mulching at least some of the plants. Gotta cut some more grass first.

zabby17 · June 25, 2012

Quote:

Originally Posted by Douglas14

Thanks for the replies.
I was weeding the tomatoes today, and noticed that the the soil feels cool under the plants without mulch. Either due to shading from the plants, or from the weeds, or both.
I will try mulching at least some of the plants. Gotta cut some more grass first.

Douglas,

I'm in zone 5, not as cool as you but a short season compared to many. We usually plant out in late May (average last frost mid May).

I mulch.

A layer of Kraft paper with some straw or chopped leaves on top. I clear a one-foot circle where each tomato goes, so I occasionally have to pull a weed or two out from within the circle, but basically it means I don't weed at all.

I am not sure I follow the logic of not mulching because it is cool where you live. I would guess that if the soil is warm enough to plant out tomatoes at all, it is warm enough to mulch, no? As much as mulch would slow down the heating of the soil in the day, it would slow down the cooling off of the soil at night, right? Or am I missing something?

I can see how you wouldn't want to mulch BEFORE putting your toms in---let the soil soak as much sun as it can as it gets higher.

Good luck. Hopefully some very experienced person right in your zone will have some firm advice.

Z

Mudman · June 25, 2012

I mulch immediately after I plant (this year early May). The benefits of less weeding and no splash up from the soil outweigh any soil temp arguments to me. And if you look at my tomatoes, and compare them to the others in my neighborhood who don't mulch, I would say it is working just fine.

ddsack · June 25, 2012

Quote:

I am not sure I follow the logic of not mulching because it is cool where you live. I would guess that if the soil is warm enough to plant out tomatoes at all, it is warm enough to mulch, no? As much as mulch would slow down the heating of the soil in the day, it would slow down the cooling off of the soil at night, right? Or am I missing something?

Mulch acts like a layer of insulation for the soil, it slows evaporation and keeps the soil at a relatively even temperature day and night. Beneficial for most regions of the country and many crops.

Not mulching dries the ground, and heats the top few inches of the soil during daylight hours. It also seems to bounce back extra heat up to the plant. Imagine walking across a clay pan desert in the heat as opposed to a scruffy pasture. True, it cools down at night, but 6 or 8 hours of extra heat each day makes a difference in a short season area, where our summer high's of 75-82 only last a couple of months. I could increase the effect by using black plastic, but personally I don't like the artificial look, though I have used it when I know I won't be around to water. Many people in my area don't bother growing long season indeterminates because they never ripen. I've been growing here over 30 years, and unless we have an abnormally cool summer, it works for me.

If I lived a couple hundred miles south of here, I might use mulch.

GaryStPaul · June 25, 2012

Doug, my in-ground tomatoes went in about the middle of May, a good 10 days to 2 weeks earlier than normal for me here in St. Paul. After a couple of hot spells, in early June, I put down a layer of newspaper around each plant, then mulched with straw. My plants are roughly the same height as yours (the ones in containers are up to a foot taller) and seem to be flourishing. I'm usually keen on getting the mulch down for the reasons others have named.

June 22, 2012	#1
Douglas14 Tomatovillian™ Join Date: May 2007 Location: Minnesota Posts: 602	Mulching tomato plants Keep in mind I live in central Minnesota. I've heard that mulching tomato plants when they are young will delay their growth, by keeping the soil cool. I'm wondering at what point, if any, mulching won't delay the plant(and ripening of tomatoes). Many of my plants have set at least a few fruits already; many of the beefsteaks are stragglers, that haven't set yet. Most of the plants have really filled out, and are around 2.5 to 3 feet tall. I've been weeding by hand, and am thinking of using dried grass clippings as mulch, after I weed them. This would prevent further weed growth, and conserve moisture around the plant. I just don't want to delay the ripening of tomatoes and plant growth. The plants already shade the soil some, so maybe mulch wouldn't make much difference in soil temps.? I'm off to one of my best tomato seasons ever, and I don't want to screw it up. I haven't been a mulcher in the past, so that's why I'm asking now. Last edited by Douglas14; June 22, 2012 at 05:16 PM.

June 22, 2012	#5
ddsack Tomatovillian™ Join Date: Jan 2006 Location: Northern Minnesota - zone 3 Posts: 3,231	I rarely mulch in ground - for the reason Douglas stated of retaining soil open to heat from the sun. Growing in the short season north, it's more important to me to have enough heat in any form I can get it, to speed growth and ripening. I do put a thick layer of grass clippings in my pots, since they heat and dry up much more easily. I also have one garden in a very sandy porous area, and I will mulch the tomatoes in the more vulnerable beds later in July if I am going to be away from home for a week or more, to retain moisture. Aside from a few short stretches in July and August, we don't have all that much humidity. Normally I spray with daconil maybe three times total during late June through July when the plants are putting on most of their growth. I quit spraying before the greenies get close to full size. I don't have much disease until the cool fall weather takes over and the season is near done anyway. Different parts of the country have different growing conditions - one size does not fit all. In fact Minnesota has at least three zones, and the growers in southern Minnesota might not do what I do. __________________ Dee **************

June 25, 2012	#8
Mudman Tomatovillian™ Join Date: Apr 2011 Location: NW Wisconsin Posts: 910	I mulch immediately after I plant (this year early May). The benefits of less weeding and no splash up from the soil outweigh any soil temp arguments to me. And if you look at my tomatoes, and compare them to the others in my neighborhood who don't mulch, I would say it is working just fine. __________________ Mike

June 22, 2012	#2
kath Tomatovillian™ Join Date: Jan 2010 Location: zone 6b, PA Posts: 5,664	I don't live in Minnesota, but I've heard the same thing, Douglas, about not mulching until July for the reason you mention. Personally, I ignore it because I don't want soil splash up on the little transplants, so I put a thin layer of shredded leaves and/or grass clippings around them at plant out and keep adding to it so the weeds don't grow through. If your plants are that far along already I wouldn't worry about it now. I don't bother drying the grass clippings but am careful not to allow them to touch leaves or stems of plants. The worms will love it and add their fertilizer for free. kath

June 22, 2012	#3
TomNJ Tomatovillian™ Join Date: May 2009 Location: Floyd VA Posts: 771	Kath's advice is spot on. I set my tomatoes outside in mid May and mulch immediately with at least 6" of hay or straw. The 28 plants in my main bed are now over 4' tall and have over 100 tomatoes set so far. Of course NJ is not MN, so you may plant out later after the soil has warmed a bit. TomNJ

June 22, 2012	#4
ScottinAtlanta Tomatovillian™ Join Date: Jul 2011 Location: Atlanta, Georgia Posts: 2,593	I mulch when the ground temp hits 70 degrees.

June 24, 2012	#6
Douglas14 Tomatovillian™ Join Date: May 2007 Location: Minnesota Posts: 602	Thanks for the replies. I was weeding the tomatoes today, and noticed that the the soil feels cool under the plants without mulch. Either due to shading from the plants, or from the weeds, or both. I will try mulching at least some of the plants. Gotta cut some more grass first.

June 25, 2012	#10
GaryStPaul Tomatovillian™ Join Date: Mar 2008 Location: St Paul, MN Posts: 158	Doug, my in-ground tomatoes went in about the middle of May, a good 10 days to 2 weeks earlier than normal for me here in St. Paul. After a couple of hot spells, in early June, I put down a layer of newspaper around each plant, then mulched with straw. My plants are roughly the same height as yours (the ones in containers are up to a foot taller) and seem to be flourishing. I'm usually keen on getting the mulch down for the reasons others have named.