Garden Doctor > Compost Additives

Questions

I've read about your Water Retaining Gel, but already planted up my containers and baskets this year. Can I still use it?

Why do some references tell you to use Vermiculite to cover seeds, and others recommend sieved compost?

How can I improve the drainage in my planters and containers?

Answers

I've read about your Water Retaining Gel, but already planted up my containers and baskets this year. Can I still use it?
Yes you can. It is easier to mix the Water Retaining Gel into the compost as you plant because you get much better distribution through the compost.

If you've already planted your containers you can make holes into the compost using a dibber. Push this deep into the compost at intervals around the planter and then place a very small amount of gel into the base. Remember that the gel will swell and absorb 400 times its own weight in water, so you need to use it sparingly. Cover over the holes with compost and water well.

Why do some references tell you to use Vermiculite to cover seeds, and others recommend sieved compost?
It depends on what you are sowing, your growing conditions and the needs of the seeds. Seeds that like a little insulation while germinating will benefit from a light covering of Vermiculite instead of compost. Seeds that need light to germinate such as basil can either be sown on the compost surface or covered over with a layer of Vermiculite. This material is so lightweight and virtually transparent that it allows light through to the developing seed. Most other seeds can be sown using either method.

How can I improve the drainage in my planters and containers?
First of all you need add a layer of crocks (broken terracotta pots) to the base of the planter. This will reduce any water logging or compaction at the base of the container that may slow the drainage of the compost. For the best results choose a gritty, well-drained compost, such as Multi Purpose Compost with added John Innes, this already contains a percentage of Perlite, an inert volcanic rock that improves aeration and drainage. If you mix this compost with more Perlite, you will open up the structure further and enhance its drainage properties. The added Perlite will not affect the overall performance of this compost and will help to improve the drainage in your containers.