2

I'm running a test on growing tomato plants with about 80% coffee, and another with about 20% coffee in layers. What one should I expect to do better?

Both have silty sand from the bottom of the compost pile, since I've heard that silt is excellent for growing plants in.

black thumb
  • 8,786
  • 2
  • 30
  • 67
  • NO. Even mulch IS NOT A SOIL SUBSTITUTE. Coffee? Do you know what silt is? Sandy loam? Sand versus clay? Why clay is used to make concrete and how it is used to make concrete? Do you know the pH of coffee grounds? How it affects the pH of the compost and then the soil? Plants need soil...little tiny pieces of rock. Do you know what the pH is of the soil in which your tomatoes are growing? Do you know what pH tomatoes need? I'll bet that soil at the bottom of your compost pile is yummy, there is a reason for that. Do not use garden soil or that soil for pots... – stormy Jul 05 '16 at 01:05
  • @stormy the silt has some coloring (black) in it, so it's not true silt, but about as thick as it. There's no rocks in the soil, probably just what animals wallowed in thousand of years ago (what I'm calling silt). My tomatoes say they need 6.2-6.8, but they can tolerate different levels of PH outside of it if needed. If I'm putting in plants on a budget I'm going to just dig some dirt out from the compost area outside of what the compost pile has as we don't care about what happens in the tall grass. – black thumb Jul 05 '16 at 02:16
  • 2
    Probably the former. The constant jittering from the caffeine should make the stems strong and aid in pollination. ^_^ – Stephie Jul 05 '16 at 07:25
  • 1
    The term 'silt' in terms of soil means a type of soil formed by running water, so the sort of thing you'd get possibly from a river bed, and it contains various minerals. You appear to be using this term to describe material from your compost pile which has composted thoroughly and is ready for use - but that is not silt, it's compost, which, whilst valuable in the garden, is no subsitute for proper alluvial silt. – Bamboo Jul 05 '16 at 09:01
  • Should be nicely highly acidic. Which isn't favorable for most plants. Start studying up on what constitutes soil, pure organic matter isn't it. There are a lot of gardening sites online that will give you far better education on this than using a Q&A site to throw darts at a dartboard blindfolded and expecting bullseyes. – Fiasco Labs Jul 05 '16 at 15:41
  • 1
    Great comment Fiasco!! You are a naughty girl Miss Stephie!! Grins!! What do you mean black thumb by 'what happens in the grass'....have you ever had a soil test done? With as much as you are doing with gardening, a soil test will teach an awful lot of necessary stuff about your resources!! Coop. Extension services through your nearest University!! A master gardener course through the same services would help you tremendously!! Have you done the mason jar with water test? Put a cup of your soil in water and shake it up. When it settles you'll see the proportions of sand, silt and clay – stormy Jul 05 '16 at 19:37
  • @stormy On the edge of the yard there's plenty of tall grass, and when I dug it, it looked black from an ancient lake filling in, and had some root material, so it has all kinds of roots, and things in it for also decomposing. Here's your information on black silt: https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=black%20silt – black thumb Jul 05 '16 at 20:17
  • I played with an area of BLUE CLAY. The kind porcelain can be made from. I dumped decomposed organic matter right on top and the next year this blue clay was 4-6" down...BLACK with dark streaks further into the soil profile. The black was decomposed organic matter that had been eaten by the macro and micro organisms and taken back down into the soil and pooped out! They do the work for you. But in no way was the dark clay SILT. It was pure clay with organic matter mixed in without having to till, mix...nada. Do the mason jar thingy... – stormy Jul 05 '16 at 20:28
  • And get a way to test the pH. Tomatoes do not like acidic. These tests have already been done up the ying yang and you need to find out what you have and whatever you plant you need to find if what you have for resources, soils, water, climate, microenvironments are condusive to whatever you want to plant. I've never used coffee and don't care to. Far better and more controlled ways to improve soils, fertilize, water...the soil you are standing upon was made in the last 100 years or less...check out tectonics. – stormy Jul 05 '16 at 20:32

2 Answers2

2

I think you're not really asking if this is soil, which requires inorganic materials ( ground rocks ) with some organic matter ( humus ), but whether this mixture is suitable medium to grow your tomatoes. There are many different types of media including those used in hydroponics ( just water alone ), flood and drain systems which use gravel, and expanded clay pellets, to traditional soil. The elements that provide the necessary growing media include support, nutrients, water and oxygen. Your mixture of coffee grounds is mostly organic matter in a form not yet available to the plants since it hasn't been transformed to humus, doesn't offer support, doesn't allow free draining so that oxygen gets to the roots, and will just clog up with stagnant water. The coffee will decompose and rot the roots. If any survive, it will be the one with the lesser amount of coffee.

Graham Chiu
  • 23,044
  • 5
  • 36
  • 92
2

100% coffee grounds will not make a great soil, you should mix it with at least 50-75% other soil. Also, coffee grounds are fine for plants that like a bit of acid (azaleas, rhododendrons, tomatoes) but will be bad for other plants.

You should also check your soil pH to make sure it's a good range for the plant that will be in the coffee grounds. I got this 3-in-1 tester for $13usd and it works well enough for me. It tests for light, pH, and moisture.

Bulrush
  • 1,726
  • 10
  • 18