It's spring time here in australia, and I have this coral bark, sangokaku. I am starting too see some leaves starting to shoot out. Previous years was a huge disappointment in seeing leaves turning brown during the hot summer months; and the bark isn't as red as it suppose to be. I am thankful for this board, now I know the reason why my tree isn't showing it's reddness branches is because i've over fertilised it. As for the leaves turning brown ...how do i prevent this from happening? should i apply a seaweed solution to my tree? the label said that it helps the tree to be more resistent in the hot summer months...
Is your maple in full sun?I did that once with my sangokaku and it died on me.I did purchase a new one and planted in full morning sun and no hot midday or afternoon sun and i have no problems with leaves turning brown. Paddy
should i fertilize my maple? it's spring. i'm kind of confused... some people here said not to fertilize maples with too much nitrogen. why is that? i always thought that nitrogen gives the green color of the leaves? and what is the difference btw a plant tonic made from seaweed and a fertiliser? thanks for your help...i just bought seasoil which guarantee to thicken the cell walls of the plant with auxins ...whatever... i hope it works, because i don't want to waste money if this whole tonic thing is a bogus.
Given the number of questions here, a lengthy answer follows, so proceed with patience. Vertrees and Gregory write, in Japanese Maples 3rd Ed., regarding maples grown in containers: “Minimal fertilization is necessary to maintain good color, and moderate watering is required. … Unlike the roots of plants grown in open ground, the roots of container plants cannot search further afield for moisture.†As regards fertilization in general, they write: “Japanese maples do not demand large amounts of nutrients. If the soils are generally fertile for most garden plants, maples will do well with little or no additional attention. It is not possible to generalize here about the nutrient needs in all the locations in which maples grow around the world. In soils of the northwestern United States, Acer palmatum seems to resent the ammonium sources of nitrogen. I have found that calcium nitrate works best, with other non-ammonium sources also working well. A balanced ‘garden’ fertilizer, such as that recommended for roses, applied lightly not more than once a year will provide for these non-greedy plants. On very poor soils and problem areas, a balanced ‘complete’ fertilizer for shrubs and trees may be used. A once-a-year early spring application, before the leaves emerge, is generally best. Newer slow-release fertilizer mixes now on the market work well.†Personally, I have not had any problems due to fertilization, which I do not typically get to until after the leaves emerge, except for perhaps a couple of Acer species, which do not leaf out until May. There has been at least one season, when I never did get to it. I learned to grow roses before maples, so I use the same products, but roses are heavy feeders, and they do love seaweed. I usually use half-strength water-soluble 20-20-20 and half-strength 16-16-16 slow-release fertilizer once a year. (I also mix a little fish meal, bone meal, and kelp meal into the potting soil, or the rare hole in the ground, when I pot the maples too, just like for all of the other plants, but that is another story.) The recommendation to avoid ammonium (NH4+ ion) in PNW soils, which are typically acidic (H+), is not the same as avoiding nitrogen (N); nitrate (NO3- ion) is nitrogen. Yes, leaves do need nitrogen, and iron (Fe) also affects the ‘green’ in leaves. The needs of variegated leaves may be slightly different, although Vertrees and Gregory do not distinquish them at all. Seaweed is a wonderful product for the garden, but as for Acer palmatum in pots, it would be important to analyze the particular product, which has been recommended. Are you inquiring about one of the products listed at http://www.seasoil.com? If it is expensive, I would spend my money on more maples. There is only one entry on the Maples forum back in 2003 regarding the use of seaweed: http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=581. There is also a recent comment about the product Sea Soil: http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=7534. It may be that you will need to water the pots more frequently, as so many of us have had to do in the Northern Hemisphere this season. I have not found any articles on the protective benefit of seaweed for maples in hotter summers. Seaweed is known to boost the disease resistance of plants, but disease is not a known or stated threat for you. Boosting the immune system to fight fungi, viruses, or bacteria has little to do with quenching thirst or adapting the water needs of the plant to the weather or water provided. However, a stronger immune system may help to fight “infection by opportunistic pathogens and attack by secondary insects†which follow drought or water shortage, but I would not rely on it. Sinclair and Lyon, Diseases of Trees and Shrubs, 2nd Ed. (Timber Press 2005). Roses regularly deal with fungi, so rosarians love to spray various seaweed concoctions on their bushes. To my knowledge, there is no difference between a plant 'tonic' and fertilizer, as both can be nutrient-specific, although a 'tonic', like tea, is a liquid and can be applied to pots or directly to leaves, whereas a fertilizer not necessarily so.
hi laurie, thanks for your kind, informative reply...i use to grow david austin roses in a teracotta pot, but they all died...they performed so well when they were in a plastic pot...maybe because with a plastic pot they have several drainage holes, whereas in a teracotta pot, there's only one drainage hole. the other thing with roses is that, i spray it with fugacide to get rid of blackspots, but the fugacide is causing the leaves to go brown and die out..why is that?
hi, i got a question...hope u guys could help: i over fertilized my sangokaku last spring..so in winter, the branches are not as red like it use to. i heard from somewhere that this is caused by too much nitrogen. my question is, is there a way to reverse this? i hope i get to see a more red bark in next year's winter.
Jumbo, my first comment is that it may help for you to add to the Location section of your personal information, from where in Australia you write since the climate varies across the continent. The difference in growing roses, or for that matter most plants, in plastic or terracotta pots is not the number of holes, which would suggest that the roses drowned in the former. Terracotta is far more porous than plastic, so it draws water out of the soil, therefore plants need to be watered more frequently when planted in terracotta pots. They are actually not a good choice for hot climates, I have heard, because they may require water twice a day in some situations. More than anything, roses need water. Depending on the climate, it could be too hot to spray fungicides very late in the morning, because the hot sun can burn the leaves when fungicide is applied. Also, if the dilution rate is not followed precisely, or if you are using a chemical, which is not specified for roses, then the chemical itself can burn the leaves. If you choose to grow roses in plastic pots again some time, you can inquire about the most disease-resistant varieties, which gives you a better start in the battle with black-spot You can also water from below the leaves, and remove any affected leaves. Some of these principals I follow with maples as well. If you were not successful with roses in terracotta pots, I would avoid them for maples as well. I would water maples from below the lowest leaves, and give them space to breath. If you feel that you truly over-fertilized the trees last year, it seems to me that you need not fertilize them this spring. If you err in this regard, the tree will inform you of its need for a particular nutrient. However, I am not aware of the color of the bark being determined by nutrients; I have not read that anywhere. Unfortunately, the two specimens of ‘Sango Kaku’ in our collection, do not have the gorgeous bark, like that in Sam’s (whis4ey) collection. I have been told that the beautiful red color is on the new growth.
