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Fertilize hydrangeas

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Hello,  I have noticed from theneighborhood website that you are expert gardeners in our neighborhood!  How wonderful!  

Since most stores are closed, I can't call anyone to ask so thought I'd send you an email.  What is a good general fertilizer for hydrangeas... I have several different varieties.. and is it too early to give them anything?  I usually just use holly tone.  Sure hope it starts to warm up soon!  thanks,

- J -

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Glad to help, J. Such a strange time but one nice thing is we are meeting more neighbors!


There are fertilizers marked for mums and tomatoes and roses, on and on but the names are really marketing tools. We gardeners will buy anything to please our favorite plants and often do buy the same fertilizer twice or three times under different labels. All any of them do is provide three basic nutrients all plants need. Some professional growers use this or that specific fertilizer mix but that is usually because they are growing in soilless potting mix rather than soil. Soilless mix lacks various minerals, big time.


Anyway, the best fertilizer is for your SOIL. You can test your soil through MSU for about $25 or through an independent lab for $100+ - but you won't need to. (Sorry to go on and on. Soil and fertilizer is the basis of EVERYTHING so it's hard for me to condense.) With a soil test result in hand you have a fertilizer prescription and stick with it for years for all plants since that fertilizer adjusts the soil to supply to plants what the soil lacks.


We've tested  two places in the neighborhood through Michigan State University labs and feel pretty confident that in our neighborhood what the soil really lacks is potassium. (But you can go to https://homesoiltest.msu.edu/ to order a soil test kit and learn how. Simple.) So a fertilizer with a high third number, high potassium, is what we need. (5-5-5 fertilizer, for instance is 5%nitrogen, 5% phosphorus and 5% potassium; those three are the every-plant-needs, 3-number code on all fertilizer.) A fertilizer that has a label 1-0-6 would be perfect for us, or 2-0-12 or 3-0-18. But not common. So look for one with a low middle number. Some " lawn" fertilizers fit. Or what we do is go organic - better for the soil because it is more lasting in the change it makes - using blood meal plus muriate of potash. Blood meal is usually 10% nitrogen or thereabouts and muriate of potash is about 60% potassium. Use 1 pound of blood meal for 50 square feet and spread 1/3 pound of muriate of potash over the same area. Do that now as the growth starts and again in fall as leaves fall and your plants will be really happy.

You can also go super-organic and chop up banana peels and pumpkins and squash and spread them on the soil - lots of potassium there! Add coffee grounds for nitrogen and you're "in" - just have to add a lot of them!


About hydrangeas - our most-asked question (we've written for newspaper magazines and lectured for years and we have a website GardenAtoZ.org where we do educational things, mostly during winter - and this year, in spring too! We've learned so much by being in and out of gardens and talking with so many people we feel we are obligated to share it.) I really hope you have the panicle-type or white snowball hydrangeas and you can stop reading now. If you have hydrangeas that are supposed to bloom blue, or ball-shaped pink, sigh, read on.


Sometimes people prescribe aluminum sulfate or soil sulfur for hydrangeas, the idea being to make the soil more acid so the flowers are deeper blue. Doesn't apply to any of the other kinds of hydrangeas and only applies IF THE BLUE HYDRANGEA FORMS FLOWERS on its own. It won't make a blue hydrangea bloom. That species of hydrangea just does not bloom reliably for us in the Midwest, winters too cold and dry, the tip buds on the branches get killed and with them go the year's potential for bloom. We tell people to send their blue hydrangeas to friends in Cape Cod or Delaware. We work for a client on the Cape, where blue hydrangeas bloom even with no one doing anything to them in drug store parking lots! Milder, moister winters. We have often talked to local garden center managers about why they even sell blue hydrangeas here and they say "Because people ask for them." Geesh!


Sorry to go on and on. If I haven't burned you out email back any time. Or watch this place on our garden forum where I will post this info and others may add more.

Janet (Steven would've answered shorter. But he's fighting with a YouTube problem right now!)

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It's the law that the label states the fertilizer analysis - the amounts of nitrogen-phosphorus and potassium.

Used to be right on the front. We bought a 10-10-10 fertilizer or a 4-5-3 fertilizer. Then fertilizer companies realized we would buy the same fertilizer twice if it was labeled for roses in one bag and for vegetables in another...

So look on the back or side for the analysis to match your soil test. If you have no soil test t o guide you, use a balanced complete formula like 5-5-5 or 2-2-2 or 10-10-10. then do a soil test because too much of a nutrient or too little can cause problems.

If you live on a waterway, look for phosphorus-free fertilizer - 3-0-2 or 5-0-4 etc. - a zero in the middle. We have so overloaded our water with phosphorus that the overgrowth of water weeds and algae is a problem everywhere.

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