This is page 5, and final, of the series on medium that will give you ideas for taking care of your houseplants any time of the year, to get them ready for the more dormant winter season, or for the active spring season.
by Mary Sue
Here’s the Dirt…page 5
Time to be a pro and get your hands dirty
When you know the needs of your plant you can combine any number of ingredients to create a perfect habitat or there are many commercial potting mediums based on these components. The ingredients you supply to your plant will dictate your plants growth. Garden soil alone is unsuitable for containers because it may contain weed seeds, pests and diseases. The drainage often becomes poor quickly without the activity of worms and other animals once you put it into a pot and place it indoors. Finding materials to mix together to create the best environment for your houseplants has never been easier. Page 2 began by exploring the many ingredients you can use in many combinations to create many different habitats.
Re-potting and Refreshing
All plants in containers, whether in soil based or soilless media, need a change of media occasionally due to compaction through decomposition, contamination from salts in the water, plants just outgrowing the pot size, or disease creeping in. You may notice symptoms of your plant asking for attention.
Slow or unhealthy new growth may be a sign of soil that is no longer supplying your plant with the habitat it needs. The media may have decomposed to a point that is unhealthy to your plant. You should re-pot your plant. If you see a white crust on the surface of the soil you may have a salt buildup. You can re-pot or refresh your plant. You may notice roots growing through the drainage holes in the bottom of the pot. Your plant is pot-bound. You should re-pot your plant. You may see gray or white fungus on the leaves or stems of your plant. Disease is setting in. You should re-pot, treat, and research the cause so you can fix it. It may be caused by something like stagnant air or too much moisture in the soil. An unpleasant odor or mushy soil may be signs of rot. In this case you will want to re-pot your plant if you find nice healthy, white roots when you remove the medium. Re-potting is done to give your plant what it needs to remain healthy in your home.With plants that have large fleshy roots like a Clivia you may see them on the top surface of the medium (see photos below). They are strong and may push the plant right out of the pot. You can re-pot or ‘top dress’ your plant.
There is often a preferred time to do this. Most often during active growth, but not while flowering. Many plants begin active growth in the spring. It will depend on what plant you are moving so know your plants requirements. Just take the plant from the pot – soil and all, gently remove plenty or all of the medium. Inspect the roots and cut away any that don’t look healthy. Dry soil will draw moisture from your roots and you want the soil to be supplying moisture. The pot you are going to use must be clean and the medium moistened but not wet. Put the fresh media mixture in the bottom ⅓ of the pot. If the roots were crowded you will want to go to one pot size larger. Lower the plant to the same height as before, and gently fill in around the roots, lightly tamping as you go. Be sure to leave plenty of space from the top of your pot to have sufficient room to water. Water your plant, remove any excess in the saucer below, and place it away from direct sun for about a week before acclimating it to its permanent place in your home.
Be careful when moving an African Violet to another pot. They do not like very large pots. Some orchids, like Vanda, do not like to be disturbed at all and you must be especially careful of the roots when re-potting. Epiphytes like staghorn fern or tillandsia are unusual in that they do not really need media but are most often attached to a board with the root section wrapped with sphagnum moss (not sphagnum peat) or placed into a hole in lava rock or a sea shell. Again, know your plant.
The medium may have decomposed and broken down to a point that there is not enough air getting to the roots or your plant may have used up all the nutrient value from the medium. When the medium is quite old (2+ years) or if you’re noticing signs like yellowing or droopy leaves and you think your plant would do better if the soil were replaced you can just swap it out. You may also notice that the new growth is not as large and healthy as you think it should be. If this is the case your plant will greatly benefit from a fresh, new soil that is the appropriate mix for it.
Sometimes there will be a white crust on the surface and if left alone will coat the sides of the pot. These are likely salts from water. You can re-pot your plant into new media or refresh the top layer. Symptoms you may notice are lower leaf drop, little growth or small new growth, leaf tips that are brown, and wilting leaves. If you choose to re-pot be sure to use a clean pot when you replace the plant. To remove the salts from the empty pot you can soak it in a mixture of 1/3 white vinegar to 2/3 water. If it does not come off with a gentle scrub you may have to use a wire brush or sand paper. If you choose to refresh there are a few things you can do. You can just remove the top layer, about 1″, of medium and replace it with fresh stuff or you can take your plant outside and run lots and lots of clean, tepid water through. This will rinse some of the salts through and freshen up the soil a bit. If you use cold water from the hose on a hot summer day you will shock the roots and the plant.
If you see roots growing through the bottom drainage holes of your pot it may be pot-bound. Some plants do very well in too small a pot – for awhile. The spider plant on the left sent out a lot of runners and baby spider plants for me to propagate. The dieffenbachia on the right was putting out lots of healthy new leaves. You may notice an abundance of flowers, beautiful new foliage or lots of runners, but after a time the plant will need more room for root growth to support the needs of all this new upper growth and will need a larger size pot. For the health of your plant do not wait too long. You may notice that your plant is wilting often and that you have to water your plant a lot more than usual. Unhealthy symptoms of waiting too long may be; slow or no growth, leaves too small, curled or wilted, or yellowing. The roots may even push the plant up and out of the soil. If it is in a 4″ pot you can move to a 5″ pot but no larger than a 6″ pot. If you move to a much larger pot your plant may get a shock, the medium will retain too much moisture and rot may set it, or will concentrate on growing only roots for a season and you may not see active growth above the soil for some time.
Disease can develop if the conditions your plant is given are not what your plant needs. The soil may be too heavy or too light, the air may be too dry or too humid, the lighting may be too much or too little, the leaves may be getting wet when you water and they do not like it, and the plant has become weak creating an opportunity for leaf spot, a fuzzy gray mold, a white powdery mildew, rot, virus, etc. It is best to remove any damage – it will not repair itself – change the soil and read about the needs of your plant so you can fix the problem.
If you notice an unpleasant odor coming from the soil your plant may have gotten too much water for too long and the roots have begun to rot. There may be a soft or black part of the plant that may be a sign of decay. This will need to be cut away. Take your plant from the pot, soil and all, and inspect the roots. Place the root ball under running water and remove all of the soil. If there are healthy roots you can pot it up in fresh new medium and you should notice rapid improvement.
Here are the steps I used to re-pot my African Violet after I noticed wilted leaves. I suspected that the soil was compacted and had been too wet for too long. I wanted to give more air circulation to the roots and decided it would benefit from a new lighter media and an added barrier between the pot and the pebble tray.
First I located a clean pot with a nice drainage hole and a saucer attached. My violet’s home is on a pebble tray in it’s own little greenhouse. They like humidity. Having a saucer between the water in the tray and the bottom of the pot will prevent any wicking of water into the medium if the pebble tray ever has too much water. I added more perlite to an already light mixture of sphagnum peat, perlite and a bit of light compost and filled the bottom 1/3 of the new pot.
I then trimmed off the wilted leaves and old flowers. My violet seems to flower all the time but I found that just now there were only 2 flowers that were coming to the end. Perhaps another indication of it being in need of a fresh, new medium. After trimming with clean scissors, as close to the base of the plant as possible so disease can’t set in, I removed it from the old pot and inspected the roots. They looked a bit tight, not too bad, and still healthy so I removed as much old soil as I could without damaging the roots, and lowered it to the proper height.
Being very careful not to get any dirt in the crown of the violet, I added the new media to the sides of the pot, gently tamping as I went around, but still holding the plant at the proper height. Care must be taken so the plant is not deeper than it was before and that there is plenty of room to add water. I then used a very soft paintbrush to get any dirt off the stems below and both the undersides and top of the leaves. Any dirt in the center, on the crown, should also be gently brushed or blown away.
The only thing remaining is to give it a drink. I then brought it back indoors and put it back onto the pebble tray. I will leave the growlight off for a few days to let it settle back in and am looking forward to new growth of both leaves and flowers.
When it is not time to re-pot your houseplant to a larger pot, you can ‘top dress’ to supply some freshness and nutrient value. Your plant may be too large or heavy for you to manage a re-potting. There will come a day when you may have to recruit helpers to manage this heavy task but for now it may need only a pick-me-up. To ‘top dress’ all you need to do is scratch up the top inch or two with a small cultivator, being very careful not to disturb the roots, remove some soil if you need the space, and add fresh medium in its place. Each of the ingredients listed state the value to your plants soil. If you need to lighten the medium due to compaction you can add sphagnum peat moss, bark fines, or perlite, etc. If you need to provide some nutrient value you can add a mixture of bark fines, compost, or humus, etc.
Last year I re-potted my Clivia. It was done flowering, had been in a pot without a drainage hole (a big no-no), so I wanted to give it new soil and a new pot with the proper drainage. This year I noticed that the big, fleshy roots were migrating to the top of the soil and were showing on the surface. I decided to just give it another layer of a high compost mixture on top of the soil.
You can also put your plant into the same size pot if you do not want your plant to get any larger. Your plant may have outgrown the space you have for it in your home. If the roots were tightly filling the pot you will have to trim them off. You can trim about 1/3 safely. Use a clean sharp knife and remove roots from both the sides and bottom. Then gently spread the roots a bit and plant into the same pot with the proper fresh medium.
Whether you are re-potting or refreshing due to compaction, a salty crust on the surface, your plant outgrowing the pot or your indoor space, or disease, the first thing you want to do is to know what type of habitat your plant comes from and will need you to provide for it in your home. Then gather clean pots, moistened media ingredients and any tools like spades and paint brushes and get your hands dirty. Your plants will be happy you did! Soil recipes