Fertilizers and bolting spinach

Dirty Fingernails

Could you give me some basic rules about fertilizer? What kind and what brand should I use on the garden? The lawn? Trees? Flowers? Much of the fertilizer that gardeners use is the pelleted kind that we buy in sacks. It offers the basic three nutrients which plants need in the greatest quantities: nitrogen, phosphorus, and potassium. They are the three numbers listed on a fertilizer sack, in that order. Many fertilizers, but not all, also will contain "micronutrients," substances which plants need in very small quantities. Personally, I choose fertilizers which contain some micronutrients. They usually are listed in a print size almost too small to read.

Nitrogen is the only food necessary for grass and fruit trees. Ornamental trees, which are not growing a crop to be picked every year, do not need fertilizer. Their large root systems bring up nutrients from deep in the soil. Grass does not need fertilizer if it is healthy, only if it seems thin or sickly.

If grass or trees are to be fertilized, once a year is a good schedule. Do not fertilize grass during hot summer weather. Grass is stressed by heat and needs to rest until the weather cools. Do not fertilize when the ground is frozen. The fertilizer might disappear in the spring runoff.

Garden vegetables and annual flowers work hard during their only growing season. They will benefit from an all-purpose fertilizer, which contains all three basic nutrients. (Specialty fertilizers like tomato food and rose food are essentially the same thing.) Fertilize annual vegetables and flowers near the beginning of their growing season. The heaviest feeders, like corn and peppers, may grow even better if they are offered a second meal in midsummer. That meal could be only nitrogen. Perennial flowers are like ornamental trees; once established, they do not need fertilizer.

If you study the small print on fertilizer sacks, you will discover that the price usually matches the amount of nutrient in the fertilizer. In other words, one with a formula of 24-35-12 will cost more than one where the numbers are 5-8-2. Regionally distributed fertilizers may cost a little less than national brands because the advertising and shipping costs are less. Organically sourced fertilizers usually are more expensive because their raw materials cost more.

With any fertilizer, too little is better than too much. Being very concentrated, too much fertilizer will burn plant tissues. If the biggest number on the sack is something like 25, try to scatter one pellet every square inch. If the biggest number is 8, try to drop pellets half an inch apart.

Manure and compost also are fertilizer, but they improve soil structure because they are totally organic. Although their nutrient composition of compost and manure is always unknown, gardeners can assume that both will be higher in nitrogen than in other nutrients. Because of their bulk, both of these additives are spread more thickly; aim for a half inch to an inch once a year on garden beds. Both compost and manure often are spread in the fall so that the living creatures in the soil can begin to assimilate the nutrients during the winter.

Both compost and manure can be left on top of the soil; they need not be tilled or dug in. Even if it sounds impossible, experiments have shown that spreading them on the surface causes their nutrients to travel just as wide and deep as if they had been tilled into the ground.

How can I prevent spinach from bolting so soon? Spinach bolts as days lengthen, so you need to take advantage of all the short days available for growing spinach. You can plant the seed as early as the ground can be worked. You can buy seed for slow-bolting varieties. You can keep the bed well-watered. Most important, you can shade the plants, beginning in the middle of May. That decrease in the daily quantity of sunlight will increase the number of days before the spinach tries to flower. All these tricks will lengthen the time of harvesting leaves.

 

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