Up, down and all around. No, that’s not the pain you feel after a long day of weeding, planting and irrigating. It is a catchy phrase to remember fertilizers.
The question now that the majority of the planting is done is when and what needs fertilizer? I am conservative when it comes to fertilizing, concentrating more on trying to build a healthy soil. I do try to remember to scratch in some fertilizer in the planting area several days before I irrigate and plant. Seeds or plants need to go into a moist soil. Years ago I neglected the irrigating prior to planting over 100 strawflower seedlings. When I went to check on them the next day, they were all prone to the ground. After a few days they did recover, but it was a lesson learned that I won’t forget.
Some vegetables are heavy feeders and need two applications of fertilizer. Others will only need one.
Taking a step backwards, our Central Oregon soil only contains 1% to 2% organic matter. That fact helps us to understand the importance of enriching the soil with compost. Building a healthy soil helps retain water and avoid major bug and disease problems.
The three numbers on the fertilizer package refer to the three elements of nitrogen (N), phosphorous (P) and potassium (K).
Nitrogen (N) energizes vegetative growth: too much and you get plant obesity — lots of green growth with no flowers or fruit. It’s great for the grass, but a failure if you are waiting for your first ripe tomato, which will not develop. Nitrogen is not a mineral and is not present in the particles of soil.
All nitrogen comes from other sources: organic matter, air or fertilizers. When nitrogen is deficient, leaves yellow from their tips toward the stem; the plant yellows from the bottom upward, and growth is stunted. The legumes, peas and beans fix nitrogen in the soil.
Phosphorous (P) is the root-pushing and blooming plant nutrient.
If you were to plant a new lawn or new landscape plants, you would want a higher second number on the label. The most effective way to apply a fertilizer containing phosphorus is to concentrate it where roots can get at it.
Plants remove more potassium (K) from the soil than any other nutrient except nitrogen and calcium. Potassium improves overall plant vigor and promotes disease and stress resistance.
In most cases, the best time to apply fertilizer is close to the time when plants need the nutrients.
Plants need the largest amount of nutrients when they are growing most rapidly. Rapid growth occurs in midsummer for corn and squash, earlier for spring plantings of lettuce and other greens.
Broccoli, Brussels sprouts, cabbage, cantaloupe, corn, cucumber, eggplant, pumpkin, summer and winter squash and tomatoes are on the list of heavy feeders and will require two applications of fertilizer: when you plant and when the fruit starts to appear.
The following are also considered heavy feeders but will only need one heavier than normal application of fertilizer: asparagus, beets, cauliflower, kale, kohlrabi, lettuce, parsley, radish, rhubarb, spinach, strawberry, sunflower and watermelon.
Light feeders include carrot, garlic, onion, potato, Swiss chard and turnip.
Symptoms of nutrient deficiencies include new leaves that are small and pale green or yellow, and older leaves that fall off or die and remain in place, usually indicates a nitrogen deficiency.
Phosphorus deficient plants show stunted growth with reddish to purple leaves.
Dark green leaves may show tip burn. There is also poor fruit, flower and root set.
Potassium deficient plants grow more slowly and exhibit loss of green color along the leaf margins or tips starting with the bottom leaves and progressing up the plant. There are low yields of flowers and fruit.
Now, back to the catchy phrase to help you remember:
UP: N — nitrogen, leafy growth
DOWN: P — phosphorus, helps produce healthy roots, plant blooms
ALL AROUND: K — potassium, important for overall plant health and resistance to water and insect stresses.
— Reporter: firstname.lastname@example.org