Wednesday, 13 May 2009

The truth about… compost!

Visiting a friend recently, he told me of his latest gardening venture. He obviously wanted to share with me since I am a keen gardener and have been running an allotment for the past 10 years. As a avid vegetable-grower, I was keen to hear! His idea is to completely cover his vegetable garden with a horticultural ground covering, secure this down with old railway sleepers and finally fill his "raised beds" with compost…

I was struck dumb.

Words failed me.

It occurred to me that somewhere along the line he had missed out on some basic understanding about the way plants grow! How could this be and was he an isolated case? My friend proceeded with his plan despite me suggesting that he might want to rethink because you simply can't grow veg year in, year out in the same compost! He isn't alone… a trip to the garden centre to see people loading up their cars with compost is testament!

The truth is that compost is not plant food and you shouldn't be fooled into thinking that if you plant in compost you are providing them with the nutrition they require. Sure, it's fine to grow your tomatoes in a large tub filled with compost – after all, they're only there for a matter of weeks, but the moment they start fruiting you have to feed them with a proprietary tomato plant food.

The plants in my greenhouse are currently potted in compost. Soon I'll have to start offering them lunch and dinner if I want a good display!

So where do plants get their nutrition? Well, it is in fact a combination of soil (I mean the stuff out planet is covered with) sunlight, air and water. And mostly this will suffice. However, if we are to grow vegetables in a small area, there is no doubt that we will (or the plants will) use up the available nutrients rather quickly – too quickly for nature to do her job.

So what's the answer?

It's very simple. You need to feed the soil. You need to put back the nutrients that have been used up. And you do this by purchasing fertiliser. This goes against the grain for most… how can we be organic if we start adding chemicals to the soil? Nowadays not even that is a problem for even the staunchest of organic gardeners as there are many naturally based products on the market designed specifically to rebalance the elements within the soil.

Salads growing happily in soil. I use very little fertiliser for this crop – just plenty of water!

So what is the point of compost?

Soils are a composition of different things: rocks, minerals, and dead, decaying plants and animals; a regular mix or organic and inorganic material. Adding compost to the soil helps to aerate the soil and retains moisture in the soil, which is good for the roots of your plants! Composting encourages micro organisms to live, breed and consequently die, which in turn are absorbed by good bacteria, which ultimately release nutrients into the soil, but the process is likely to be slower than the rate at which we grow our spuds!

Regular and correct feeding is essential if you want your plants to grow well and to produce the crop you desire.


AlyGatr said...

Thanks for sharing! I'm a very amateur gardener and take any advice I can get :) I've never really thought about composting, but as our lawn was transitioning from winter dormancy to spring/summer "awakening" (which here in Texas happens REALLY fast) the landscaper that sodded our backyard recommended that we NOT bag our lawn clipping and allow them to compost. We also aerated the lawn and added some gypsum to help motivate a green lawn.

Right now my biggest challenge is getting my lantana plants to rebloom. They survived the winter, as did all of the ones planted by our community in the common areas, but mine are the only ones not blooming! I have plenty of green, but no flowers :(

Lolley said...

I never bag up the lawn clipping as such. I prefer to layer lawn clippings with what comes from the kitchen and shredded prunings… the grass seems to accelerate the process.

We say phosphagen for flowers, but I'm not sure about lantana!