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Help With Top Dressing Dry Amendments

Hey DGC – Looking for some advice from the organic soil growers. I’m finishing up my fourth run in 15 gallon living soil fabric pots. I’ve been feeding the soil with a variety of dry amendments through teas. I would like to do more top dressing but I’m nervous about burning my plants. I have a layer of mulch (straw and cannabis leaves) and ground cover (red and white clover) in my pots. I have a basic knowledge of what amendments to apply at what point in the grow cycle but any suggestions or tips would be appreciated .I have heard using Alfalfa Meal can burn your plants if a little too much is used. Trying to avoid similar potential pitfalls .

Thanks-Lord Blueberry


5 responses to “Help With Top Dressing Dry Amendments”

  1. Jason9086 Avatar

    I really wouldnt worry about kelp meal burning i think even a cup to one and a half cup (even 2 cup) in each 15 gal is a good and not excessive top dress. When im in flower i top dress with a pretty hot dry rose amendment by down to earth at like a cup per 10 gallons and do it twice during the growing season… very hard to burn with organics but you can run in to issues with guanos and blood meal sometimes

  2. JustCoolin Avatar

    Also alfalfa should mostly be used in veg as the hormones can affect the flowering cycle. Just lightly topdressing once a week or every other week til about week 3 in flower. Otherwise you’ll have too much nutrition going into the ripening phase and plants will stay green and growing strong. Especially kelp seems to prolong flower. Just know it won’t be plant available right away, it will take time. Some nutrients like fish emulsion will be heavy in nitrogen and easily available. Also some guano products are hot just be cautious with those. I don’t think you’ll burn your pants.

  3. SOUP Avatar

    One good general rule of thumb is to not topdress after about week 4-5 of flower (depending on your flowering time). That allows at least a month or so for any excess nutrients to get consumed before its time to harvest. Its best not to have a lot of fresh amendments still breaking down too late into flower. Having an excess of nutrients in late flower can interfere with your plant’s natural finishing processes.

    I find it works really well to do a small topdress at the start of flower, and then do another one at the start of week 4. This helps make sure your plants have all the nutrition they need through stretch and during that peak time around week 5-6 when they are start stacking buds. Splitting your topdressing up into two separate applications also reduces the likelihood of over doing it.

    Its a good idea to always mix your amendments into some compost or castings, and then topdress your plant with that enriched compost mix. The compost will help break down the raw amendments and make them more available to your plants. It also acts like a buffer so you arent applying anything too strong directly to your root zone. You can water in with some recharge or compost tea right after a topdress to increase the effectiveness even more. Make sure to recover with mulch after you topdress too. This will help keep the new topdress layer moist and active with microbes.

    As far as burning with amendments goes… topdressing is a lot safer than mixing directly into soil, so most stuff is pretty forgiving (especially when you mix with compost first). Be careful with stuff with high numbers like blood/bone meal or guanos. Or just avoid that stuff all together, I find its not worth the trouble and there are better alternatives. That’s the kind of stuff thats much more likely to burn or cause issues. Fish bone meal is a good alternative “bloom booster” if you use it in small amounts.

    Alfalfa can burn if you go overboard with it, but its mostly an issue when you mix it into soil. Its pretty forgiving if you topdress with it, especially if you mix into compost first.

    Crab/shrimp/crustacean meal is great for topdressing during flower as it has N, P and Calcium. It also provides chitin which can help deter pests. Insect frass is also good stuff.

    Gypsum is great for providing calcium and sulfur. The size of the particles determines how quickly it breaks down. The powdered stuff is available almost immediately (which is awesome), but don’t go too overboard with it.

    Anyhoo… overall topdressing is very forgiving, just mix amendments with compost first and be extra carful with things with higher NPK numbers. 🙂👍

    1. Lord Blueberry Avatar
      Lord Blueberry

      Thank you all for that great information. I have a lot less fear of top dressing now . All the great tips will help me schedule applications which is a huge help to me.

  4. Dude Grows Avatar

    This was featured on EP 1007. Thanks for the post!

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