Beginner Gardening: I'm new to this. Any advice?, 0 by tapla

tapla wrote:
Basically, I'm saying that the convenience of out of the bag soils has no direct correlation to their value as a growth medium for your houseplants. We often go much longer between repots (and I'm drawing a distinct difference between repotting and simply potting up. Repotting includes removal of old soils and pruning of roots, which guarantees the opportunity for maximum vitality, while potting up is simply moving the plant to a larger container and adding a little soil. This procedure guarantees that the plant will forever grow at reduced vitality - at least until root issues are corrected. Not only is this thought supported by my own observations as I go about repotting hundreds of plants each year (bonsai), but you can find the same information in multiple reference texts used by nursery/greenhouse ops, including Plant Production in Containers by Dr. C. Whitcomb.) than we should, so we need to use a soil that will retain its structure (remain well-aerated) from repot to repot. Peat/compost/coir-based soils are very water-retentive as they come out of the bag, and can be counted on to collapse within the first growth cycle.

There really is no way to work around these soils, because if you have to water in sips to avoid root rot, you assure that salts will build up in the soil. You actually cannot change drainage characteristics or ht of the perched water table by adding perlite or pine bark, unless you make these amendments the largest fraction of the soil and at least 60-70% of the o/a volume. Adding perlite to heavy soils only reduces the amount of soil in a given volume and reduces the amount of water the soil will hold. To illustrate this, imagine adding 1/4 cup of perlite to a cup of pudding, then ask yourself if the pudding will drain any better?

For plants to grow with the best vitality, they need a certain amount of air and moisture in the soil, air being the most important because you can adjust the amount of water by varying the frequency, but the o/a pore space cannot be appreciably changed for the better once the planting is established. You can achieve the durability and aeration your plants want by using ingredients that are of a larger particle size than peat/compost/coir as the primary ingredient of the soil. This can be as simple as mixing a large fraction of suitably sized pine bark and some perlite into your bagged soil, or you can learn to make your own soil from ingredients like those listed in the thread I linked to above.

I grow all my houseplants in the soil you see in the picture. Essentially, it is the soil I've been using for bonsai and houseplants for about 20 years. It won't collapse (structurally) and it will retain excellent aeration for far longer than it would be prudent to go between repots. It is extremely easy to tend plants in this soil, and because of its physical properties, it offers the grower a wide margin of error when it comes to watering and fertilizing.

Al

This message was edited Apr 18, 2010 10:44 AM